Bulletin


Bulletin
OF THE

Illinois State Laboratory
OF

Natural History

Urbana, Illinois, U. S. A.

STEPHEN A. FORBES, Ph.D., L,L.D.,

Director

Vol. XII. June, 1917 Article IV.

THE ZYGOPTERA, OR DAMSEL-FLIES, OF ILLINOIS

BY

Philip Garman, Ph.D.



ERRATA AND ADDENDA

Page 5, first column; line 2, for Sheperdia read Shepherdia; line 11, for

amcricana read americanus.

Page 9, line 5 from bottom, for XYII read X.

Page 42, line 4 from bottom of key, for Pyromorphidae read Eiicleidae.

Page 73, line 7 from bottom of key, for or read atid seldom.

Page 100, just below key, insert as follows:—
The following species were examined:

LopUoptilus cloisclla Clemens

Laverna brevivittella Clemens

Page 107, lines 8 and 9 from bottom, page lOS, line 10 from bottonr, and page

110, line 10, for Cucullianae read Cuculliinae.

Page 110, line 8 from bottom, dele Polia.

Page 112, line 19 from bottom, for Metathoracic read Mesothoracic.

Page 129, line S, for never read sometimes.

Page 131, at end of second line insert Paleacrita Riley.

Page 15S: first column, after Paleacrita, 127, add 131; second column, after

Polia dele 110.

Page 170, line 4, for Strayiomyiidae read Stratiomyiidae.

Page 243, line 2, for alternata read alternatus.

Page 307: line 5 from bottom, for with read and; line 16 from bottom, for

Homeodactyla read Homoeodactyla.

Page 314, line 15 from bottom, for Cecidomyiidae read Coenomyiidae.
Page 321, line 12 from bottom, for Stratomyia read Stratiomyia.

Page 324, line 6, for pantherina read pantherinus.

Page 370, line IS, for Empidoidea read Empididoidea.
Page 428, line 8 from bottom, for ilesnottim read Mcsonottun.
Page 461, line 10 from bottom, for Aeshnide read Aesluiidae.

Page 478, line 13 from bottom, for vigilas read vigilax.

Page 519, line 2, dele side.

Page 528, line 10, for caruncluatum read caruncvlatum.



CONTENTS

PAGE

Introductiou 411

Morphology .413^38

Nymph 413

Adult 423

Life history and habits 438-445

Egg 438

Nymph 439

Adult 444

History of the Zygoptera 446—464

Paleontology 446

Ontogeny 450

Phylogenetic comparison of Zygoptera and Anisoptera 453

Classification 464-577

Family Agrionidae 466

Subfamily Agrioninae 466

Family Coenagrionidae 476

Subfamilies:

—

Lestinae 477

Coenagrioninae 499

Bibliography 577

Index to genera and species 584

Abbreviations used in lettering plates 586



ArticIvE IV.

—

The Zygoptera, or Damsel-flies, of Illinois* By
Philip Garman, Ph.D.

Introduction

The order Odonata includes all insects known as dragon-flies in

the broad sense of the term. The adults are characterized by the

possession of four membranous, net-veined wings which are of nearly

equal size. The mouth-parts are fitted for biting and the metamor-
phosis is incomplete. The males are distinguished by accessory gen-

italia on the second and third abdominal sterna. The nymphs are

aquatic, and are recognizable and separable from other aquatic forms

by the large hinge-like labium which folds beneath the head. The
order is subdivided into two suborders, the Anisoptera and the

Zygoptera. The adults of the Anisoptera have large, broad wings,

but little contracted at the base and with numerous cross-veins. The
wings of the Zygoptera are usually narrowed at the base and possess

fewer cross-veins. The Anisoptera usually rest with wings spread

horizontally ; the Zygoptera usually with wings held vertically. The
nymphs of the suborders are easily separated by means of the respira-

tory apparatus, the Zygoptera having three tracheal gills at the caudal

end of the abdomen, and the Anisoptera having no caudal tracheal

gills, being provided with rectal gills instead.

The Odonata form one of the strangest orders of insects withwhich
an entomologist has to deal. Their bizarre form, striking colors, and
peculiar habits make them an object of much curiosity on the part of

the layman as well as the object of many studies on the part of the

scientist. The prevalence of the popular terms, snake-feeders, snake-

doctors, and similar names, shows that there are many superstitions

concerning the group.

As is well known, the Odonata are predaceous, in all stages, upon
other insects, particularly upon those insects annoying to man, the

flies and mosquitoes, and in this role they must be classed as beneficial.

Their harmful activities are few, but they sometimes destroy young
fish, they occasionally injure plants by the insertion of eggs, and,

•Contributions from the Entomological Laboratories of the University of Illinois

No. 53.



412

most serious of all, they do not discriminate between beneficial and
noxious insects, but destroy b(jth. An instance of the fact last men-
tioned is the recently reported feeding of Anas Junius on the honey-

bee. In no case, however, is it probable that the harm done overbal-

ances, or begins to counterbalance, the good wliich tliese insects do
in the destruction of biting Diptera.

The classification of the nymphs of Zygoptera is in a backward
state as compared with the classification of the adults. This is due
especially to the fact that immature forms are not easily collected and

that their classification is particularly difficult. An intensive study

of the nymphal characters has shown tiiat there are, within certain

genera, groups of nymphs the species of which are much more closely

related to each other than to the members of other groups of the same
genus. These groups correspond to groups of adult species in the

identification of which the characters of the anal appendages of the

male are mostly relied upon. Little attention seems to have been given

by taxonomists to the females, and where species are represented in

collections by females only it is exceedingly difficult to determine them.

Again, when studying nymphs, one is often successful in rearing a

number of females, but almost any amount of painstaking work may
fail to produce a male. In such cases still more inconvenience is

experienced when it is found that the reared females can not be named
because of the fact that the published synopses are based largely upon
male characters.

It is with a view to clearing up some of the obscure features of

the classification and lessening the labor of determination that nymphs
and adults, including both sexes, have been considered together and
tables prepared for the separation of both.

All obtainable biological data have been added for the sake of com-
pleteness; but it is fully realized that the data given here are incom-

plete, and can only be made complete after many years of diligent

study.

Nymphs of several species which are apparently new have been

reared in the course of the study and are described herein for the first

time. Some of the remaining species which doubtless occur in Illinois

but which have not been collected by the writer, have been obtained

through the courtesy of various people, and the list has been completed

as far as possible in this way.
Certain problems concerned with the nomenclature have presented

themselves, the most important of which concerns the adoption of

family names. According to the ruling of the International Commis-
sion on Zoological Nomenclature (Muttkowski, 'lo: 15) Agrion re-



413

places Calopteryx, and the family name Calopterygidae must be abol-

ished. The change has caused much confusion because of the former

application of the name Agrionidae ; but it seems practically certain that

further change would only result in still greater confusion, and the

family names as used by Muttkowski are, therefore, adopted without

change.

The use of the common names "dragon-fly" and "damsel-fly" in

referring to the Anisoi)tera and Zygoptera respectively, causes no little

confusion because of the frequent use of the term dragon-fly to denote

the order as a whole. In the following pages, the words Anisoptera

and Zygoptera will be used exclusively to designate the subdivisions

of the order.

ACKNOWLEDGMENTS

I take pleasure at this point in expressing thanks for the valuable

aid which Dr. A. D. MacGillivray has given by his careful supervision

of work and thoughtful criticism during the course of the study.

Thanks are also due to Dr. S. A. Forbes for granting financial support

from the funds of the Illinois State Laboratory of Natural History

as well as for the loan of the collection of Zygoptera belonging to that

laboratory. I am especially indebted to Mr. E. B. Williamson for his

kindness in permitting me to examine his collection of Odonata ; and
I further wish to thank Dr. E. M. Walker and Dr. J. G. Needham
for the loan of specimens of zygopterous nymphs, and Dr. P. P. Cal-

vert for the identification of material sent him.

Morphology

NYMPH

The nymphs are distinguishable from all other insects by the

possession of three more or less flattened, caudal, tracheal gills. They
are slender, delicate insects of the same color as the surrounding veg-

etation or environment in which they live and at first sight seem
hardly capable of the predatory habits of the order. They are usually

covered with fine hairs or spinules which collect an ambuscade of dirt

and rubbish. Their slender cylindrical abdomens resemble the stems

of plants and weeds, and the caudal gills remind one frequently of

growths of algae. Such adaptations as these render the insect most
inconspicuous in its natural habitat.

Head.—The head of the nymph is somewhat oval or pentagonal

in outline when viewed from above, and is usually longer than wide.

The sutures are indistinct even in full-grown nymphs with the excep-



414

tion of the epicranial suture, which is a Y-shaped hne on the dorsum

of the head, near the caudal margin. Sutures are wanting, separating

vertex from occiput, occiput from postgenae, and postgenae from

genae. The vertex occupies that part of the dorsum of the head cap-

sule caudad of the arms of the Y; and the occiput and postgenae

together, the portion of the caudal aspect of the head not occupied hy

the occipital foramen and the compound eyes. The genae are the areas

mesad of the ventral margins of the compound eyes. They fuse with

the postgenae (Fig. 7, pg) near the ventral margin of the head.

Extending caudo-dorsad on the caudal aspect from the ventral articu-

lations of each mandible, there is a distinct ridge which disappears

near the middle of the head. Tlie trochantins of the mandibles are

present as indistinct triangular areas laterad of the bases of the mandi-

bles (Fig. 7, tm).

Compound Eyes.—The compound eyes of the nymphs, like those

of the adult, are very large. They occupy perhaps one-third of the

dorsal surface of the head, nearly the whole of the lateral surface,

and part of the ventral. The facets are hexagonal and similar to those

of other insects.

Ocelli.—The ocelli are wanting during nymphal life, but in the

later stages the adult ocelli may be seen through the transparent cuticle

of the dorsum of the head. Thus it often appears as if the nymph
had ocelli when in reality there are none present, as can be proved by

an examination of the final exuvium, or by dissection.

Antennae.—The antennae, in all full-grown nymphs, consist of

seven segments. The distal segment is short in most species and the

connection between it and the preceding one is frequently obscure, so

that it seems as if the appendage had only six segments. The first

segment is usually thicker than the remaining ones, and in the

Agrionidae is as long as all the rest of the segments together. In the

Coenagrionidae, the third segment is the longest and each of the seg-

ments distad of it is shorter than the segment preceding. The two

proximal ones are not constant in lengtii but are always shorter than

the third.

Mandibles.—The mandibles are normalh^ hidden from sight by

the large labium and the flap-like labrum. They are located on the

ventral surface of the head and are well formed for mastication. They
are irregular in outline, though somewhat rectangular, bearing four

short, strong teeth along the distal margin and several smaller teeth

mesad and proximad of these.

Maxillae.—The maxillae (Fig. 22) are attached to the ventral

surface of the head and the following parts are distinguishable: a

1



415

triangular cardo (cd) ; a narrow sclerite which may be known as the

cardella (cl) ; and a long, oblong stipes, to the distal end of which

are attached two appendages representing palpus, lacinia, and galea.

The lateral, narrower one of these (mxp), the palpus, bears on its

surface a number of strong setae. There is sometimes a distinct swell-

ing at the base of it but there is no distinct suture between the proximal

and distal portions. The remaining process, regarded as the fused

galea and lacinia (glc), is much broader at the base and tapers con-

siderably at the apex, where it bears about five strong hooks. It is

provided with two rows of weaker setae extending proximad from

the hooks. The identification of this piece as fused galea and lacinia

is due to the supposed occurrence, in adults of certain species, of a

suture extending across it from the proximal to the distal end. So far

no case has come to my notice in which this suture is present, but a

study of Ephemerida (Morgan, '13) and Plecoptera (Fig. 31) on the

other hand, proves conclusively that the piece has been correctly inter-

preted.

Labium.—The labium differs greatly f-rom that of the ordinary

insect in being free from the head at the point of articulation of the

submentum, and in being folded so that mentum and submentum are

approximated when the piece is at rest. It is applied to the ventral

surface of the head, forming a sort of mask; and an idea of its general

location and shape may be obtained from Figures 1—4, 6, and 7.

Several forms of labia occur in the suborder which, although sim-

ilar in general construction, differ in certain particulars. The forms
of the lateral arms or lal^ial palpi, the mentum, and the submentum
are different enough in different species to enable one to determine the

family, and sometimes the genus, at a glance (Figs. 8-13). The sub-

mentum is a hollow tube of cuticle (Figs, 2, 4; sm) articulating

at its proximal angles with the ventral wall of the head capsule.

It is filled with muscles for the extension and retraction of

the labium as a whole, and varies in shape from cylindrical

to flat, and from comparatively short, hardly extending caudad
of the posterior margin of the head, to long and slender, reach-

ing caudad of the metacoxae. The mentum-ligula, or median
lobe (Figs. 8, 9; ml), is likewise filled with heavy muscles which
move the labial palpi. It varies in shape, in the degree of the con-

traction proximad, and, more important for purposes of classification,

in the number of mental setae (Figs. 10, 12, 13 ; ms). The median lobe

is sometimes notched or cleft at the apex but is more frequently with-

out indentation. The glossae and paraglossae are present at the distal

end of the labium, but the suture between them and the mentum is in



416

most cases indistinct. The latter, however, seems to be represented in

species having the deeper median clefts. The palpi are present in the

so-called "lateral arms", the distal .segments being represented by the

movable hooks (Figs. 8, 9; Ipa). The lateral arms also bear a

number of raptorial setae in some species (Fig. 10). In capturing

prey,, which consists of mosquito and other soft aquatic larvae, the

nymph swings out the hinged lal)ium, opening and closing the lateral

arms like a pair of jaws. The victim is then drawn back toward the.

mouth and the heavy maxillae and mandibles finish the work.

Labial Muscles.—The muscles operating the labium have been

studied by few, and studies that iiave been made seem incomplete. It

has therefore.seemed advisable to examine them in detail. The struc-

tures have been determined by means of cross and longitudinal sections

and verified as far as possible by gross dissections.

The median lobe (Figs. 1.2; ml) contains four large muscles for

operating the lateral arms. These are attached proximad directly to

the dorsal wall of the submentum, dorsad of the hinge (Fig. 4). At
the point of attachment to the labial palpi, the muscles are usually

modified to form tendons. With the submentum there are also tw-o

pairs of muscles, which, though not as large as those of the median

lobe, play an even more important part in the operation of the piece.

The points of insertion of the mental muscles are of especial interest

and give clues to the actual function of each muscle. The dorsal

inner pair (Figs. 2, 4) is attached proximad to the tentorium and distad

just above the hinge which is between the median lobe and the sub-

mentum. The remaining, or ventral, pair is attached to the chitinous

ligament or rod described below—a structure present only in the

Odonata. The rod (Figs. 3, 4, 7; cr) is unpaired and is attached to

the ventral wall of the head just caudad of the hypopharynx. It

extends obliquely caudad and dorsad in the plane of the meson and is

attached again to the dorsal wall of the submentum, at which point it

expands in such a way as to form the top of a T. The ventral pair of

muscles are inserted on the base of the chitinous rod (Fig. 4). From
this point they extend over the mento-submental hinge and attach

themselves to the ventral wall of the median lobe. A third pair of

muscles, present at the base of the submentum, is attached to the ventral

wall of the head caudad of the hypopharynx, extends caudad and
dorsad, and is inserted on or near the tentorium.

The exact function of each of the muscles contained in the sub-

mentum is difficult to explain, and it is probable that no single pair

can be said to produce a given result with the exception of those operat-

ing the labial palpi. Thus it can be seen that the oblique muscles at



417

the base of the labium are important in throwing the submentum away
from the head. In this, however, they are aided by the presence of

the obHque, chitinous rod and by the contraction of the dorso-sub-

mental muscles. The action of the ventral pair seems reasonably clear,

as it can, by contraction, swing the mentum back towards' the sub-

mentum, and by action in conjunction with the chitinous rod, swing

the submentum back towards the head. The mentum is swung out

away from the submentum mainly by the action of the dorsal sub-

mental muscles which are attached to it above the hinge and in this

capacity are aided to some extent by the contractifin of the muscles

within the mentum, especially those which operate the labial palpi.

Glossac and Paraglossac.—The glossae and paraglossae are fused

and the suture is vmtraceable except in the embryo (Butler, '04). The
nymph of Agrion shows a fold extending between the labial palpi

beneath the median cleft. This fold probably represents all that is

left of the suture between mentum and paraglossae. In other species

the course of the suture is marked by a row of setae, the mental setae.

The area occupied by the submentum is indefinite, but it is probable

that the mental setae, even if secondary in origin and occurring only

in the more specialized forms, are near the location of the original

mento-paraglossal suture. The latter suture has been thought to

become approximated to the distal border of the median lobe, but this

seems doubtful after comparisons of nymphal and embrvonic labia

(Butler, '04).

Labial Palpi.—The palpi of the labium are represented by the lat-

eral lobes, (Figs. 8, 9; Ipi, Ips). These lobes bear at their distal ends

a number of fixed hooks, which are simple in some cases, but may
become modified in others, for instance in the Coenagrionidae, in

which the middle hook is replaced by a blunt process with teeth at

the apex. That the fixed hooks have not the same origin as the mov-
able ones, is shown by the fact that the latter bear, in certain nymphs,
a number of long setae. The movable hook has been considered (But-
ler, '04) as a modified palpal segment, and this interpretation is un-
doubtedly the correct one. The proximal segment or body of the

lateral arms also bears in many species of nymphs a row of long setae,

the number of which is used extensively in the classification of the
group. In Agrion, however, this row of setae is wanting and the lat-

eral lobe bears only two small setae near the base of the movable hook.
The body of the mentum is also provided with rows of setae in all

genera except Argia, Agrion, and Hetaerina, the bristles being in two
divergent lines beginning near the meson slightly distad of the center

and reaching nearly to the proximal end of the labial palpi.



418

Median Lobe.—This term is used for convenience and includes the

fused glossae and paraglossae.

Hypol'harynx.—Perhaps the most conspicuous portion of the

hypopharynx is a circuhir pad between the tips of the maxillae, and

easily seen on raisinj^ the mentum-ligula. It is covered with minute

setae possibly indicating the location of sensory organs. The pad has

been given the name laminula by Berlese, and corresponds to the lingua

of other insects. However, it is somewhat difficult to homologize any

part of it with other forms on account of the very great modification.

Propharynx.—The propharynx lies closely applied to the ental sur-

face of the labrum, and has essentially the same shape as the latter.

It possesses no features worthy of mention.

Protlwrax.—The prothorax, the large segment just caudad of the

head, is preceded by a smaller segment, the microthorax, which forms

the neck. The sclerites of the microthorax are not well developed in

the nymph. Most of the sutures of the prothorax are also indistinct

and are represented by furrows in the cuticle. The pronotum (Fig.

23, pme) is divided by depressions into caudal, mesal, and cephalic

areas. The caudal lobe is, in most species, a narrow transverse area

along the caudal margin ; the mesal lobe comprises the larger part of

the pronotum, and is usually divided by a median furrow into two

lateral areas; and the cephalic lobe includes the transverse area

cephalad of the median lobes and caudad of the cephalic margin. The
furrow which marks the caudal boundary of the cephalic lobe and the

median furrow of the pronotum form a Y, and at the point of union

of the three arms there is usually an invagination. The proepimera

and proepisterna are areas ventrad of the pronotum on either side.and

dorsad of the coxae, and are separated by furrows which are very dis-

tinct in some genera, especially Lestes. In this genus the furrow sep-

arating the two pieces extends dorsad a short distance from the point

of articulation of the procoxae and the procoxal process (Fig. 25,

pcxp), bends slightly cephalad and then caudad, extending to the caudal

margin of the prothorax. In the Coenagrioninae there is often a sec-

ondary ridge extending dorsad from the procoxal process but this does

not mark the boundary between proepisternum and proepimeron. The
prosternum is the area between the procoxae, and is much broader than

that of the adult. There is no indication of distinct areas or sclerites,

but near the caudal margin of the prosternum and between the coxae

are the two invaginations of the furca (Fig. 24, fi).

Mcsothorax and Mctathorax.—The mesothorax and metathorax
are greatly different from the common type of thorax, in consequence

of an approximation of the mesepisterna on the dorso-meson in the



419

mesothorax and an approximation of the epimera on the ventro-meson

in the metathorax; all of which is accompanied by an enormous de-

velopment of muscles within the thorax in preparation for the active

life of the adult. The wing-cases, too, are early approximated, and
there is a corresponding reduction in the size of the mesonotum and
metanotum.

Mesonotmn.—The mesonotum is divided into two regions by the

closing together of the mesepisterna. The cephalic one, the prescutum,

just caudad of the pronotum, is a shield-shaped plate with slightly

projecting cephalo-lateral angles. On the cephalic margin of this piece

on the meson there is an invagination, the prephragma, which, how-
ever, is usually not well developed in the nymph. The second portion

of the mesoscutum lies between the cephalic pair of wing-cases. This
represents combined scutum, scutellum, and postscutellum. It is nar-

rowed cephalad, has a slight projection on each cephalo-lateral angle,

the anterior wing-processes (Fig. 21, awp), and a similar, longer, one
on each caudo-lateral angle, the posterior wing-processes (Fig. 21,

pwp). Near the cephalic margin on the meson is an invagination indi-

cating the location of the mesophragma. Immediately caudad of the

mesoscutum and between the second pair of wing-cases is the

metascutum. This is similar in shape to the caudal sclerite of the

mesoscutum, though somewhat larger, and possesses similar wing-
processes on its lateral angles. There is no subdivision of the

metascutum, but there is a deep invagination on the meson near the

cephalic margin—the metaphragma.
Mcsothoracic Spiracles.—These are located just laterad of the

prescutum and are always hidden to a greater or less extent by the

overlapping pronotum. Large tracheae are connected with them and
the spiracles are doubtless functional during nymphal life. The meso-
stigmal plates are wanting in the nymph, and their derivation will be

discussed later, in the description of the adult.

Mesoplenra.—These sclerites, occupying somewhat more than the

cephalic half of the lateral aspects of the pleura, are approximate on
their dorsal margin between the prescutum and the wing-cases. The
dorsal border extends from the mesostigma caudad to the second pair

of wing-cases. The cephalic margin follows the caudal margin of the

pronotum and extends ventrad from the mesostigma to the mesocoxae.
The ventral border follows the contour of the coxal cavity; and the

caudal border, forming a suture which may be known as the inter-

pleural suture (Fig. 25, insu), extends from between the mesocoxae
and metacoxae dorso-caudad to near the base of the second pair of
wings. The mesopleura are each divided by three furrows into three



420

areas, two of which, the cephalo-dorsal and cephalo-ventral (Fig. 25,

seps, ieps), comprise the episterna, and the caudo-ventral, the epimera

(Fig. 25, epm). The ventral areas of the episterna (ieps) are known
to odonatologists as the infraepisterna, and the dorsal ones incorrectly

as the episterna. For convenience in designating the parts the latter

may be known as the supraepisterna (seps).

Mesostcrnum.—The mesosternum, that area between the meso-

coxae, the caudal margins of the prosternum, and the cephalic margins

of the metasternum, is not divided into separate areas, but the furcae

are present and the deep fureal invaginations are very distinct (Fig.

24, fi).

Mctaplcnra.—The boundaries of each metapleuron are the inter-

pleural suture, the metacoxae, the metathoracic wing-cases, and the

pleura and sternum of the first abdominal segment. The sclerites are

each divided into three parts, the cephalic two comprising the

metepisternum (supraepisternum and infraepisternum), and the caudal

one, the metepimeron. The metathoracic spiracles are located on these

pieces near the union of the dorsal border of the metinfraepisternum

with the interpleural suture.

Metasternum.—The metasternum (Fig. 24, mtst) is similar in

shape to the mesosternum, but is divided by sutures into three areas.

The invaginations of the metafurcae are also prominent and a suture

extends caudo-mesad from each. The two sutures unite on the meson,

extend caudad for a short distance, separate again, and extend laterad

and caudad of the coxae. The areas on each side of the mesal line are

the two halves of the sternellum (mtsm). Caudad of the sternellum

is a broad sclerite possibly representing the first abdominal segment.

This may be known as the intersternum (Fig. 24, ints). There is no
corresponding sclerite on the dorsum caudad of the thorax, but it may
be that the latter portion has been lost. If, however, the intersternum

be considered as a vestige of an abdominal segment, it will be found
by actual count that there are twelve segments represented in the abdo-
men of the nymph, a fact which makes one skeptical of the above inter-

pretation. In some species, the area is membranous, and it is possible

that the sclerite is nothing more than accessory membrane which has
subsequently become chitinized.

Trochantins.-—The trochantins are wanting in the Zygoptera, and
the mesal part of the coxae articulates directly with the sterna.

Legs.—The legs are usually slender and not well adapted for cap-

turing prey, the labium being wholly relied upon for that purpose.

The coxae are nearly spherical and slightly compressed. The trochan-

ter consists of two segments. The proximal segment is narrow and



421

capable of being telescoped into the coxa. The second segment is

longer, and its ventral length is greater than its dorsal. The femora
are subequal in length, the posterior being slightly longer, especially

in Argia and the Lestinae. The tibiae are also nearly equal in length

and are slender and cylindrical. The tarsi have three segments. The
proximal segment is short and is extended below the second segment
so that its ventral length is greater than its dorsal. The second segment
is usually about twice the length of the proximal but, like the proximal

one, is extended on the ventral side. The third segment is longer

than either of the two proximal ones, being in some cases nearly

twice as long as the second and four times as long as the first. At the

distal end of the third segment, on the ventral surface, there can be

found a small sclerite which probably represents an extra tarsal seg-

ment and is known as the pretarsus (Fig. 19, pta). It is drawn out

distally into a slender process. The tarsal claws vary to some extent

in length but are always sharply pointed and somewhat swollen at base.

They are never bifid at the tip as in the adult. The legs of the nymphs
never bear the long spines characteristic of the adult but, instead, there

are weak setae or short spinules which collect particles of dirt and
enable the insect to hide with ease. In the Agrioninae, there are to

be found short, minute, three-pointed scales at the ends of the tibiae,

the function of which is obscure (Fig. 19). The tarsi in all species

possess two to four rows of short setae on the ventral surface. The
markings of the legs vary with the genus, but consist largely of black

rings on the femora and tibiae. In Agrion, nearly the whole of the

femur is dark except a whitish ring near the apex. The tibial bands
are mostly restricted to the proximal third and are lacking in most
species.

Wing-casc$.—The wing-cases of Zygoptera appear early and at

the completion of nymphal life usually extend as far caudad as the

fifth or sixth abdominal segment (Fig. 25, wc). The tracheation of

the pad is often obscure but the veins are sometimes plain enough to be

of value in identification. Ontogenetic studies of the wings can only

be made at intervals during the growth of the nymph, the obscure

nature of the contents of the pad making such study difficult during the

greater part of the time. In no case do we find the radial sector actu-

ally crossing over the media as in the Anisoptera, and, as pointed out

by Needham ('03), the subnodal cross-vein formed by the proximal

end of the radial sector has been reduced and lost. The distal portion,

however, may be seen in Lestes, but not usually in other species, and
branches from the second media a short distance from its separation

from the first media (Fig. 14, Rs).



422

Abdomen.—The abdomen is always composed of ten complete

body-rings. The eleventh segment, seen best in Lestes, is represented

by the small basal processes (Figs. 5, 18; An) to which the caudal

gills are attached. The twelfth segment, supposed to be present in

the minute sclerites bounding the anus, is apparently wanting or indis-

tinct. Each body-ring is without sutures but is roughly divided by
the lateral carinae into sternal and tergal areas. In the Coenagrionidae,

the lateral carinae of the first eight segments are known as lateral

,

keels (Fig. 25, Ik). In Lestes, the caudal extremity of each keel is

sometimes drawn out into short setae and is setose or hairy along the

margins. Marginal setae are also present in the Coenagrionidae but

the heavy caudal setae are wanting.

Sexual Appendages.—It is claimed that the sexual appendages of

the nymphs (Balfour-Browne, '09) can not be seen and differentiated

until about the time of the seventh molt. From personal observations,

however, it would seem that the appendages appear much earlier than

this, and possibly as early as the fourth molt. The male genital ap-

pendages are located on the ninth abdominal sternum and consist of

a simple pair of short, sharp, conical styli, near the ventro-meson.

There is also an indication of the location of the male copulatory

organs on the ventral surface of the second and third sterna (Fig.

24, ag), though nothing definite is formed there until the adult

emerges. The ovipositor of the female is composed of six processes

developing from the eighth and ninth sterna (Figs. 5, 18; oce, oca).

Four of these are similar in appearance, being slender, curved, blunt

projections extending commonly beyond the end of the ninth segment
and frequently beyond the apex of the tenth. Laterad of this double
pair of inner valves, can be found a pair of lateral styli which differ

from the inner valves in being pointed at the tip and much broader at

the base. The origin of the four median valves is partly from the

eighth abdominal segment and partly from the ninth, the external

ventral pair (oce) being derived from the eighth.

Caudal Gills.—The caudal tracheal gills are present in the earliest

stages and are reported to have been seen in the embryo. They vary
from linear to broadly obovate in outline and from triangular to

linear in cross-section. Cuticular pigmentation, if any, is either in

transverse bands or is diffused over the entire gill. In many cases

the tracheae contain pigment, which causes them to stand out in

marked contrast to the rest of the gill. Along the margin of the gills

are rows of spines or setae, which differ in number and extent in dif-

ferent species. The lateral median ridges of the flat type of gills also

possess rows of setae, but they are difficult to observe and are of little



423

importance in classification. Two or more main tracheal trunks enter

each gill and send ofi branches towards the margins. The mode of

branching of the trachea is characteristic of many species, as is also

the degree of pigmentation.

A closed tracheal system has been considered possible and even

probable in the Zygoptera, but thus far no connection has been traced

by me, with the highest magnification obtainable, between the ends of

the branches of the tracheae. The normal function of the gills is one of

respiration, the minute tracheae being supposedly able to take up the

oxygen from the water and to supply the animal with a sufficient quan-

tity of the gas. Observations show, however, that complete loss of

gills does not injure the insect to any appreciable extent ; and it has

been suggested that they also have cuticular and possibly rectal respira-

tion, the latter thought to have been demonstrated in the Agrionidae.

In young nymphs there is a pulsating movement in the region of the

rectum, but cross-sections of the abdomen of Ischmira verticalis and
several species of Enallagma show that there is no connection of the

tracheal S3'Stem with the alimentary tract other than a few small

branches. What seems to be a more serious impairment of life activ-

ities in the loss of the gills is the decreased power of locomotion which
the insect suffers, the gills having the same importance as the tail of a

fish. Loss of gills frequently occurs, in which case new ones are pro-

duced ; but these appear only after the insect has molted, always remain
small, and are usually abnormal in figuration and tracheation (Fig.

77a). For different types of gills see Figures 48-72, 75-77a, and 80.

Cerci.—Anal appendages corresponding to cerci are present dorso-

laterad of each lateral gill and vary in shape from tubercular to sty-

liform (Figs. 5, 18; ci).

ADUI,T

The adults of Odonata are distinguishable from all other orders

of insects by the type of their wing venation. The wing is character-

ized by the presence of a nodus and a stigma and a large number of

secondary cross-veins. The presence of accessory genitalia on the

second abdominal segment of the male is another unique feature. The
Zygoptera are for the most part separated from the suborder Anisop-
tera by the habit of folding their wings vertically when at rest. The
abdomen is much more slender than that of the Anisoptera, and the

wings are different in being contracted or petiolate at the base.

Head.—In general appearance the head is wide and the eyes are

very prominent, and as the head moves on a point of the microthorax
its angle of rotation is very great. The epicranial furrow is present



424

on the dorsum near the caudal margin, similar in position to that of

the nymph, and is, as a rule, indistinct unless the head is specially pre-

pared in caustic potash. The furrow begins near the caudal margin

of the dorsum, extends cephalad a short distance, forks, and extends

latero-cephalad, caudad of the ocelli, to the margins of the compound
eyes (Fig. 32, epcs). It can not be traced to the occipital foramen,

but the homology of the furrow as a whole can not be doubted. There
are three ocelli (o) cephalad of the Y, which are sometimes elevated

above the surface of the head forming the so-called ocellar area. A
furrow extends cephalad from the angle of the Y between the lateral

ocelli and forks just caudad of the median ocellus. This furrow is

present in many orders of insects, but its true homology is not known.
The front includes that portion of the dorsal aspect cephalad of the

epicranial Y, between the compound eyes and cephalo-ventrad to the

fronto-clypeal suture (Fig. 32, f). Cephalad of the median ocellus

there is always a short, deep, transverse furrow which, although pres-

ent in most Odonata, must not be mistaken for a suture. The fronto-

clypeal suture does not reach the margins of the compound eyes on
either side. There is always a polished area on each side of the clypeus,

which is a portion of the gena (Fig. 32, gn). The clypeus (Fig.

32, cly) extends ventrad of the fronto-clypeal suture and is divided

into two parts by a transverse median ridge. The dorsal part, often

dark and heavily chitinized, is the postclypeus ; the ventral one, more
weakly chitinized and often wrinkled, is the anteclypeus. The clypeo-

labral suture separates the clypeus from the sclerite ventrad of it, the

labrum (Fig. 32, Ibr). This sclerite is only slightly bilobed in most
species of Zygoptera, the ventral margin is directed caudad, and the

lateral margins are convexly rounded. Laterad of the bases of the

mandibles, which lie at either side of the clypeus and labrum, there

are small semi-ovate sclerites, the trochantins of the mandibles (Fig.

32, tm). The fronto-genal sutures are indistinct, but are represented

by furrows extending from the dorsal articulations of the mandibles

to the antennal fossae and laterad to the compound eyes. That por-

tion of the. head on the dorsum and caudad of the arms of the epi-

cranial Y, is the vertex (Fig. 32, vx), but it is not separated by a dis-

tinct suture from the occiput, which occupies the dorsal half or third

of the caudal aspect (Fig. 30, oct). The postgenae, which occupy the

ventral half of this aspect are separated from the genae by the oblique

ridge mentioned above. There is another ridge starting from the

ventral condyle of the mandibles (Fig. 30, ocr) but extending dorsad
instead of latero-dorsad. This ridge disappears near the middle of

the head.



425

Ocelli.—The location of the ocelU has already been described. They
are moderately large, elliptical, and grouped in a triangle (Fig. 32, o).

Compound Byes.—The compound eyes (Figs. 30, 32; ce) are

large and contain a large number of ommatidia. They are located

mostly on the lateral aspects of the head, but sometimes extend well

onto the dorsum.
Antennae.—The antennae (Fig. 32, ant) are usually composed of

four segments. The condyle of the scape is especially prominent.

The two terminal segments are styliform and resemble a single seg-

ment. The greatest variation in the different segments lies in the

length of the first, which ranges from hardly more than half that of

the second segment, to an equal or greater length than that. There

is also a less noticeable variation in the length of the third segment.

Labium.—The labium (Fig. 37) is the ventral movable appendage

of the head. It is a broad flat piece and covers nearly one-fourth the

entire ventral surface. The submentum (sm), the proximal sclerite, is

attached to the head and neck and comprises that part of the labium

dorsad of the hinge when the labium is at rest. Immediately cephalad

of the hinge there is a small, almost linear, transverse area, the mentum
(me). Beyond this there is a large subtriangular piece with a deep me-
dian, distal cleft and a suture-like furrow extending to the proximal

end. This piece is the median lobe (ml) and represents fused glossae

and paraglossae. On each side of this median lobe there are heavy
blade-like lobes, the labial palpi, which connect with the proximal part

of the median lobe. The fixed proximal segment is the palpiger (pi),

the large movable distal portion is the proximal segment of the palpus,

and the short blunt movable appendage borne by the proximal segment
is the distal segment (Ipj, Ipc). There is a long, sharp, fixed hook
mesad of the distal segment of the palpus, which in most cases is

longer than the distal segment of the palpus.

Maxillae.—The maxillae are just above the labium, one on each

side of the mouth-opening. When the labium is applied to the ventral

surface of the head, the maxillae are hidden, except the cardines and
the caudal half of the stipites. The cardo and cardella are bent at

an angle to the stipes, but when removed from the head along with the

rest of the maxilla they are seen as two small sclerites attached to the

proximal end of the stipes, the cardo being triangular and attached to

the stipes, and the mesal side of the triangle forming the suture be-

tween cardo and cardella. The cardella (Fig. 28, cl) is a very irreg-

ular .sclerite which articulates with the head capsule. Attached to the

distal border of the stipes, the quadrangular sclerite which forms the

body of the maxilla, are two appendages, the lateral more slender two-



426

segmented appendage being the palpus, the broader one, the fused

galea and lacinia. The palpus has a number of large setae scattered

over the surface. The galea-lacinia is more or less compressed, and

the distal margin has about six irregularly placed hooks arranged in

two rows. A marginal fringe of heavy setae extends proximad from
the hooks. In Hetaerina, if the galea-lacinia be placed on edge, there

will be seen a strong indentation between the two rows of hooks, an

indication of the fused condition of the piece. A study of Plecoptera

(Fig. 31) and Ephemerida (Morgan, '13) offers convincing reasons

for the interpretation of this piece as galea and lacinia fused, as com-
pared with a belief in the reduction of the galea, or in the fusion of

this with the palpus instead of the lacinia, or in the reduction of the

palpus. All degrees of fusion, from complete separation (Fig. 31) to

complete fusion and disappearance of the suture, may be Jiad in series

selected from these two orders.

Mandibles (Fig. 30, md).—All of each mandible is hidden beneath

the labrum and labium except the lateral surface. The teeth are strong

and heavily chitinized and the distal margins are divided into two pro-

jections, the cephalic one bearing a number of teeth, the caudal one

with a number of teeth and cutting edges arranged in the shape of a Z.

Hypopliarynx (Fig. 30, hp).—The visible portion of the hypo-

pharynx appears as a semicircular part between the tips of the max-
illae. It is much more heavily chitinized than that of the nymph, and
usually has a number of long setae attached to each lateral surface.

Propharynx.—The propharynx is closely applied to the interior of

the labrum and clypeus and presents no features of interest.

Microthorax (Figs. 27, 29, 36, 39).—The microthorax comprises

the neck sclerites, and is much reduced in the Zygoptera. The dorsal

and ventral sclerites (notum and sternum) and the episterna are want-

ing. The only portions remaining are the conspicuous lateral plates,

the epimera (min). In many species the epimera are much widened
on the caudal third, and this portion is almost completely divided by

a deep cephalic indentation. The indentation separates from the main
part of the epimera a bell-shaped dorsal part which serves as a buffer

for the head and is to some extent freely movable. The ventral part

is slightly larger than the dorsal buffer, but is thrown into folds, and
the cephalic part of the ventral piece is drawn out into a long tapering

point. The tips of the epimera are fastened together by ligaments and
the head rotates upon the apices of the two together, which rest against

the body of the tentorium.

Thorax.—The thorax comprises the three body-segments caudad
of the microthorax. The first conspicuous ring is the prothorax. The



427

mesothorax and metathorax together form the division caudad of the

prothorax and are so closely united that they appear as one segment.

Prothorax (Figs. 27, 29, 36, 39; 41, pn).—The lateral margins of

the pronotum are usually indefinite because of the disappearance of the

noto-pleural suture or because of excessive pigment. Lestes is prob-

ably the best form in which to study the prothorax on account of the

clearly marked sutures between the sclerites. The caudal margin of

the prothoracic dorsum extends caudad as a thin blade-like projection.

There is a suture or furrow which extends cephalad from the lateral

limit of the blade-like projection and marks the lateral extent of the

pronotum (pn). Shortly cephalad of the caudal margin of the pro-

notum and parallel to it there is a deep furrow which resembles a suture

and extends from one lateral margin to the other. The area between

this fold and the caudal margin is the caudal lobe of the pronotum.

Cephalad of the lateral extremities of the caudal lobe, the suture mark-
ing the lateral boundary of the pronotum arches dorsad a little and
reaches the cephalic margin of the prothorax at the base of the mi-

croepimeron. At this point there is a second transverse fold in the

pronotum which is, however, large and more irregular than the caudal

one mentioned above. The area between it and the cephalic margin
is the cephalic lobe. Near the dorso-meson, the cephalic fold bends

caudad and there is a deep invagination here, the prophragma. Be-

tween the prophragma and the caudal lobe there is a furrow which
separates the remaining portion of the notum, not included by the

caudal and cephalic lobes, into two equal, mesal or median lobes (Figs.

36, 39; pme). The principal variations in the prothorax lie in dif-

ferences in the caudal lobe and in the sculpturing of the dorsal sur-

faces of the mesal lobes. In Nehalennia the caudal lobe is deeply

incised and in Chromagrion (Fig. 170) this lobe is not only incised,

but there are also two flat points, projecting laterad, one on each mesal
lobe. Many other modifications also occur, most of which are sec-

ondary sexual characters.

Proplcura (Figs. 36, 39).—The propleura, those areas ventrad

of the pronotum and dorsad of the coxae, are each subdivided into

three areas. Extending dorsad from the lateral procoxal articulation

(pcxp) there is a distinct suture which becomes indistinct before reach-

ing the lateral margin of the pronotum. This suture (pps), the pro-

pleural suture, is usually depressed and the depression is continuous

with that forming the cephalic fold of the pronotum. Caudad of the

propleural suture there is a large, rounded area which forms the caudo-
lateral angles of the prothorax, and ventrad of this is a small, falcate

area. Both areas constitute the proepimeron (pepn), there being no



428

real suture between the two. Cephalad of the propleural suture is a

somevvliat trianjjular area, tlie proepisternum (peps), the cephalo-

ventral angles of which are drawn out and extend ventrad in front of

the procoxae. The cephalo-ventral arms of the proepisterna are fused

with the propreepisterna. Between the dorsal triangular portion of

the preepisterna and the nvicroepimera is a small, much-wrinkled area,

which appears to be composed of a number of sclerites. This, how-
ever, belongs to the proepisternum.

Prostcrnum (Figs. 27, 29).—The cephalo-ventral arms of the

episterna, as described above, extend ventro-cephalad and become ap-

proximate but not cjuite contiguous on the ventro-meson. Caudad of

the approximated ends of the episterna there is a large shield-shaped

ventral sclerite the caudal margin of which is concave. This is the

fused sternum and presternum (prst). The caudo-lateral angles are

usually acute, and at the tips of these angles are found the deep in-

vaginations of the furcae (fi). Caudad of the sternum and between

the furcae is a heavily pigmented chitinized area, the sternellum, which

extends about as far caudad as the caudal margins of the coxae. In

some cases there is within the sternellum an elliptical or oval depressed

area much resembling a true sclerite. This is a secondary formation.

On each side of the meson, caudad of the sternellum, is a heavily chi-

tinized bar which extends latero-caudad and is attached to the meso-

thorax. These bars represent the furcella (fi).

Mcsothorax and Mctathorax (Figs. 40-47).—This division of the

thorax bears the two pairs of wings and the second and third pairs

of legs. A glance at the mesothorax and metathorax of any dragon-

fly will show that the wings, instead of being borne on the mid-dorsum

of the thorax, are situated far to the rear and are inserted just above

the cephalic margin of the first abdominal segment. This change in

wing position has brought changes in the structure of the thorax as

a whole, including the reduction of primary sutures and the appear-

ance of many secondary ones, and as a result the external thoracic

skeleton of Odonata is as complex as that of the highly specialized

Hymenoptera and Diptera.

Mcsnotum (Figs. 41, 44, 46, 47).—As has been mentioned in

tlie nymphal description, the mesepisterna are approximate on the

dorso-meson. In the adult the two have united and fused, a single

suture being left, extending from near the caudal margin of the pro-

notum to the wing bases. In some cases this suture is slightly elevated,

forming a carina (dc), but it is often flattened at the point of fusion

of the two pieces and the suture nearly obliterated. Cephalad of the

dorsal carina there is a small somewhat rhomboidal area, the prescutum



429

(mscl). There is a deep invagination near its cephalic angle but no
invaginations of the internal skeleton occur here. Caudad of the

caudal extremity of the dorsal carina and adjacent to the wing bases

there are two small, frequently subcrescentic pieces which are approxi-

mate on the mesal margins and extend well towards the first lateral

suture of the thorax. These are the combined mesepisternal paraptera

(p). Caudad of the mesepisternal paraptera, but on a distinctly lower

level and between the first pair of wings, is the second portion of the

mesonotum, which consists of a number of irregular hummocks sep-

arated by depressions, sutures, and ridges. Just caudad of the parap-

tera on the dorso-meson there is a very deep invagination of the mesa-
phragma, which is situated near the cephalic margin of the mesoscutum.

(msec). At this point the mesoscutum is narrow, but widens soon

after extending caudad a short distance and forms a process, the

anterior wing-process. From this point the margin extends caudad

and forms a similar process, the posterior wing-process. The caudal

boundary of the scutum is formed by a heavy chitinous line, bent

caudad and extending from side to side between the caudal wing-

processes. From the caudal wing-processes the lateral margins of the

mesonotum, now the scutellum, extend caudad to the point of entrance

of the spring-vein (Figs. 46, 47; spn) which always marks the caudal

iiiargin of this sclerite. The central portion of the scutellum is ele-

vated to form a sort of knob, which is heavily chitinized. The portions

on either side of this are depressed and as a rule less heavily chitinized

tlian the elevated portion. The area caudad of the spring-vein is the

postscutellum (mopl), the latter extending as far as the deep fold

vv'hich forms the cephalic border of the metaprescutum. •

Mctanotnm (Figs. 46, 47).—The metaprescutum (psct) is a nar-

row, transverse, heavily chitinized sclerite forming the cephalic mar-
gin of the metanotum. It is in great part covered by the membranous
postscutellum of the mesonotum but can usually be seen through the

latter. On the lateral angles, there are slight ental projections. Caudad
of the transverse prescutum, there are four large areas composing
the scutum (mtsc) and three deep longitudinal folds which mark ofif

the four areas, but no primary sutures. There is also a somewhat
irregular area caudad of the four larger ones. The caudal margin of

the scutum is depressed laterad, and the latero-caudal angles project

and form the anterior wing-processes. The metascutellum (masl)
is similar to the mesoscutellum (mosl), the caudal boundary being

marked by a spring-vein (spn) and the sclerite, as in the former case,

having a raised central portion and depressed lateral ones. The postscu-



430

tellum comprises the area caudad of the spring-vein and cephalad of
the first abdominal segment.

Mcsothoracic Spiracles and Mcsostigtiuil Plates (Figs. 4.1, 43-45,
212-216).—The mesothoracic spiracles of Zygoptera are large and
have exceedingly large tracheal trunks connected with them. As in

the nymph, the spiracles have migrated dorsad and are located near
the lateral angles of the mesoprescutum and beneath the projecting

caudal margins of the pronotum. Adjacent to the spiracle on two.
sides, are two heavy plates, the ventral one of which is highly polished

(Fig. 45, mstv), allowing the prothorax to play upon it to a certain

extent. The caudal plates (mstg) are usually triangular and assume
a variety of forms in different species. Both of these plates belong
to the peritreme of the spiracle. The caudal plate has been assumed
by Snodgrass ('09) to be homologous with the depressed area in

Anisoptera which extends across the dorsum just caudad of the pro-

notum. A study of the nymphs of Anisoptera proves conclusively

that such is not the case, for in the nymph the depressed area may be

observed to develop from the mesepisternum. Another possibility in

the derivation of the caudal plates is that they have arisen from the

mesoprescutum, and the wide depressed area of Anisoptera may also

have had the same origin. This is strongly supported by the apparent

disappearance of all traces of the prescutum in the adults. There is,

however, a remnant of the prescutum in the adults of Gomphus where
the area occupied by the prescutum lies entirely within the transverse

depression and the true stigmal plate is closely applied to the stigma.

From this it seems that the depressed area of Anisoptera can not be
homologous with the spiracular plates of the Zygoptera, but that it

must have developed simply from a depression of the mesepisterna.

Use has been made of the caudal stigmal plates in the classification,

especially in the case of the females, of the genus Argia. Kennedy
('02a) and Calvert (Calvert and Hagen, '02 :i03) were the first to call

attention to these plates in America, but their use was hinted at as long

ago as 1865 by de Selys ('65: 381). In the genus Argia the caudo-
mesal angles are the variable parts of the sclerites. There is considerable

difference also in the plates of females of the Coenagrionidae, and
individuals of this sex may often be separated by the use of this

character. In the Lestinae and Agrionidae, the character seems to be

without value, which fact makes the members of the genus Testes, at

least, one of the most difficult of all genera of Zygoptera to determine.

Mcsoplcura (Figs. 43, 45).—The mesopleura are closely united

to the metapleura in most Zygoptera and the interpleural suture has
been lost in many cases. This suture can be traced for its full length



431

only in the family Agrionidae (Fig. 45, insu), in which it extends

from a point between the mesocoxae and metacoxae, caudo-dorsad to

the caudal margin of the first pair of wings.

Mcscpistcrua (Figs. 43, 45).—The mesopleural suture, dividing

the mesopleura into episterna and epimera, may be traced by locating

the lateral articulation of the mesocoxae (Fig. 40, mcp) and the

mesopleural wing-process (wp)—a heavily chitinized process extend-

ing from the caudo-dorsal margin of the thorax into the membrane
at the base of the first pair of wings. The suture will be found to ex-

tend cephalad, beginning at the wing-process, parallel to the dorsal

carina, as far as the cephalic third of the mesothorax, where it appar-

ently forks, and sends one branch cephalad and the other ventrad to

the coxal process (mcp). The horizontal fork is a secondary suture

and separates the small sclerite above the coxae, the infraepisternum

(ieps), from tlie rather large oblong sclerite, the supraepisternum

(seps).

Mcscpinicra (Figs. 43, 45).—The mesepimera lie caudo-ventrad

of the mesopleural sutures. In the Coenagrionidae they are fused

with the metepisterna and the interpleural suture is obsolete except

near the wing bases. In the Agrionidae the interpleural suture is dis-

tinct throughout its course, and the metepimera are then elongate

sclerites with the dorso-cephalic angles considerably rounded.

Mctaplciira.—The key to the metapleura is the metapleural suture,

which may be traced in a similar manner to the mesopleural suture.

This may be done by finding the metacoxal articulation and the meta-
pleural wing-process (wp), situated at the base of the second pair of

wings, anjl following the suture between the two points.

Metepisterna (Figs. 43, 45).—The metepisterna are those portions

of the metapleura cephalad and dorsad of the metapleural suture (Fig.

45, mtsu). Like the mesepisterna tliey are divided into two separate

sclerites, a small one dorsad of and adjacent to the coxae, the metin-

fraepisternum, and a larger, elongate one dorsad of the metinfraepi-

sternum and extending from the cephalic margin of the latter caudo-
dorsad to the bases of the wings—the metasupraepisternum (seps).

The latter is narrowed to about half its width above the infraepisternum

and usually bears the metathoracic spiracles (Fig. 43, mtsl) within

the constricted portion. In many species there is a secondary suture

extending between the spiracle and the metapleural suture (Fig. 45).
Metepimera (Figs. 43, 45).—Caudo-ventrad of the metapleural

suture is the metepimeron. The metepimera are contiguous on the

ventro-meson. In the Agrionidae the boundaries of the sclerite, be-

ginning with the metacoxal process (mtcp), may be indicated as fol-



432

lows:—The margin extendi ventro-mesad (Fig. 40), meeting its fel-

low from the opposite side on the meson, then extends caudad half-

way from tlie coxae to the first abdominal segment, bends laterad to

the elevated lateral carina, caudad again to tlie abdomen, then dorsad

(Fig. 45) along the wing bases to the metapleural suture (mtsu),

which forms the dorso-cephalic border of the sclerite. At the caudo-

ventral angles of the epimera there is a small triangular sclerite which

if- apparently cut off from the main portion of the epimeron. The
primary suture follows the ventral margin of the deep fold which

occurs at this point. The latero-ventral carina does not follow the

ventral suture of the epimera all the way from the al)domen to the

coxae, but, instead, follows a more direct line along the ventro-lateral

margins of the thorax and diverges from the suture half-way from
the abdomen to the coxae (Fig. 40). In the Coenagrionidae the

sutures marking the ventral borders of the epimera are less distinct

and do not follow quite the same course (Fig. 42).

Mcsostcrntiiii and Mctastcrnum.—The approximation of the coxae

in the adults of Zygoptera has brought about profound changes in the

mesosterna and metasterna.

Mcsoslcrmiiu (Figs. 40, 42; mst).—The key to the mesosternum
lies in the invaginations of the furca (mfi) which mark the caudal

limits of the sternum. In the Agrionidae the elevated parts of the

sternum and sternellum form a distinct hour-glass figure with the furca

on either side of the contracted portion. The margins of the sclerites

are, however, parallel to the elevated portions, but are somewhat de-

pressed. If the cephalo-lateral angles of the sternum are followed

to the sides of the thorax they will be found to extend neajly as far

dorsad as the dorsal margins of the mesinfraepisterna. The cephalo-

lateral arms are expanded dorsad, and there are apparently several

sclerites represented in the upper portions, possibly the remnants of

the mesopresternum (Figs. 43, 45; pst). Along the lateral margins

of the sternum cephalad of the furcae there are obscure invaginations

which represent the prefurcae (mpf ). These are difficult to see from
the exterior unless the cuticle is cleared.

McsostcrncUnm (Figs. 40, 42 ; mstm).—The mesosternellum is

similar in shape to the sternum except that the caudal margin is convex

and heavily chitinized in some groups, notably the Agrionidae. The
chitinized portions represent furcellae. From the caudal margin of

the mesosternellum there extends a short, heavy, chitinous projection

which sinks into the metathorax, and is lost from sight beneath the

metasternella. This is a part of the metasternum (Figs. 40, 42).



433

Mctastcnutiit (Figs. 40, 42).—This sclerite is even more pro-

foundly modified and distorted than the mesosternum. The meta-

coxae are ahnost contiguous and the muscles attached to the meta-

sternum along the meson have drawn it well into the interior. The
metafurcae can only be seen upon dissection of the thorax, and are

to be found closely approximated along the ventro-meson. The pre-

furcae (mtpf) are a short distance cephalad of the furcae (mtfi).

The presternum and sternum are fused, and the cephalo-lateral arms
extend around the cephalic margins of the coxae and unite with the

m.etinfraepisterna. The sternellum is represented in each sclerite

mesad of the caudal half of the metacoxae, the caudal boundary being

marked by two nearly contiguous chitinized spots on the meson (Figs.

40,42).
Intcrsterimm (Figs. 40, 42; ints).—The closing together of the

metepimera has apparently resulted in the isolation of a portion of the

sternum, near the abdomen. Comparisons with the thorax of

Orthoptera and other orders show that this may be a portion of the

abdomen, but in this case it is probably the cuticular membrane de-

veloped between the abdomen and -thorax. The possibility that this

sclerite represents an extra abdominal segment has already been dis-

cussed under the description of the nymphal thorax. The name inter-

sternum has been applied to this area.

Postcoxal Area.—The area on the thoracic venter between the

lateral carinae, caudad of the metacoxae and cephalad of the first ab-

dominal sternum, is the postcoxal area.

Legs.—The legs are long and comparatively slender, and have
long setae arranged regularly in rows (Fig. 35). They are not adapted
for walking or running.

Coxae (Fig. 35, c.x).—The coxae are large and globular, and there

are prominent ridges on the lateral surfaces of the procoxae and the

caudo-lateral surfaces of the mesocoxae and metacoxae.
Trochanters (Fig. 35, tr).—The trochanters are much smaller than

the coxae and are divided into two short pieces in all families. The
ventral length of both portions is much greater than the dorsal.

Femora (Fig. 35, fe).—The femora are long and cylindrical and
without carinae except in a few genera. The ventral surface is pro-

vided with two rows of long black setae (fs), varying in number from
three or four on the fore tibiae to as many as sixteen or seventeen on
the hind tibiae.

Tibiae (Fig. 35, ti).—The tibiae are likewise long and slender and
have a double row of setae on the ventral surface. In the fore tibiae

of most species the setae of the cephalo-ventral row are conspicuously



434

flattened. The comb (tic) formed by these closely placed setae is

probably used for cleansing the mouth-parts or the antennae. There
is a great deal of variation in the length of the tibial setae and also in

the number present in different subfamilies.

Tarsi.—The tarsi are always composed of three segments, the seg-

ments increasing in length from the proximal to the distal end (Fig-

35, ta). They are also provided with a double row of setae beneath,

but these are never as long as the tibial or femoral setae.

Prctarsus.—The pretarsus (Fig. 19, pta) is beyond the end of the

third tarsal segment and consists of a small shield-shaped piece on the

ventral surface just beneath the bases of the claws. It extends back
into the third segment, and in order to be seen best the claws should be

pulled outward a little. There is also a small projection attached to the

lip of this sclerite, but this is not homologous with the empodium of

other insects. The ventral apical margin of the last segment of the

tarsus is deeply emarginate on each side of the pretarsus.

Clazus.—The claws are long and slender and the tips are always

notched or bifid (Fig. 35, cw). The rays are seldom ecjual in length,

and in some species the notch is far proximad of the apex.

Wings (Figs. 73, 74, 78, 81-90).—All Zygoptera have four sim-

ilar membranous wings. In respect to venation and shape, the genus

Hetaerina may be said to have the most primitive wing of any zygop-

teron found in Illinois (Figs. 74, 78). The position and course of

the veins in the wings of this genus are as follows :—The costa, first

longitudinal vein, forms the cephalic margin of the wing. The sub-

costa, second longitudinal vein, extends half the length of the wing
from the base and ends abruptly in a short fork which marks an in-

dentation in the margin. The two forks of the tip of this vein are

in line with a heavy cross-vein caudad of it, and the brace formed by

the alignment of the cross-vein and the subcostal forks is known as the

nodus. The third longitudinal vein extends from base to apex of the

wing and is composed of fused radius (R) and media (M) as far

distad as the nodus and first radius (Rj) plus the second subcosta

from nodus to apex. There are a number of cross-veins extending

between costa and subcosta from the base of the wing to the nodus

—

the antenodal cross-veins. Between costa and radius, distad of the

nodus and proximad of the stigma—the heavily chitinized spot near

the apex of the wing—are the postnodal cross-veins. The remaining

branches of the radius are united, forming the radial sector (Rs), and

separate from the main trunk at the nodus. The course of the radial

sector is difificult to follow because of its crossing one or two of the

median veins. In Hetaerina the radial sector branches from the radius



435

at the nodus, crosses the first median vein, the first vein caudad of it, at

the point where the second median vein separates from the first, fol-

lows the second vein for a short but indefinite distance, being fused

with it, and then crosses over to the longitudinal vein caudad of the

second media, and continues its course to the margin of the wing (Fig.

74). The point of separation of the radial sector from the second

media is not evident, there being no oblique cross-vein as in the Ani-

soptera. The vein uniting the caudal end of the cross-vein over which

the radial sector crosses, to the main radio-medial trunk is known as

the bridge (seen in Lestes and Ischnura, Figs. 81, 85; br), and is

secondary in origin. In Hetaerina the trachea of the bridge is fully

as strongly developed in the nymph as any other of the main tracheal

trunks. Such a feature would perhaps throw some doubt on the actual

formation of the bridge in this suborder were it not for the strong

comparative evidence present in the Anisoptera. The bridge reaches

R-plus-M about half-way between the nodus and the base of the wing.

About one-third of the distance from the base to the nodus is a strong,

oblique cross-vein, the arculus (Figs. 81, 85; arc), from the middle

of which two longitudinal veins arise. These veins are the third and

fourth median veins (M3 and M^), respectively, the cephalic one being

Mg. A short distance from the arculus there is another heavy cross-

vein connecting M4 with the longitudinal vein caudad of it. The cross-

vein probably represents the medio-cubital cross-vein. The four-sided

area enclosed by this vein, the portions of M^ and the longitudinal vein

caudad of it (the cubitus) and distad of the arculus, forms what is

known as the quadrangle (qd), and corresponds to the cell first M4.

The cubitus extends from the base of the wing to the distal side of the

quadrangle, where it forks and sends out two longitudinal branches

caudo-laterad to the margin of the wing. The forks are Cu, and Cus,

or first and second cubitus. The anal vein (A) consists of a single

heavy trunk extending from the base of the wing and apparently con-

necting with the cubitus at the point where the latter forks. The dif-

ferent anal veins can not be traced because of numerous secondary

cross-veins.

Many variations occur in the above wing-venation, but instead of

a discussion of each in detail the reader is referred to figures 73 and

81-90 which show the types of venation occurring in the remaining

genera of Zygoptera found in Illinois.

Abdomen (Figs. 91-100, 104).—The abdomen of all Zygoptera is

cylindrical and composed of ten complete segments. In all of the seg-

ments the sterna are much reduced and hidden by the overlapping

terga. The pleura are still more reduced, so that no portion of them



436

can be seen in the normal insect. If the body be softened and the

lateral margin of tiie terj^a extended, the pleura appear as membrane
between the marijins of the terj^a and the sterna. In this membrane,

near the cephalic-lateral margin of the first eight segments, the ab-

dominal spiracles are found. The terga of all the segments are always

large, are bent around from the dorsum onto the lateral aspect of the

abdomen, and usually extend slightly onto the venter. A single

tergum, then, has a dorsum and pleuron of its own. The terga are -

usually transversely rugose on the dorsum, and the lateral margins are

always paler than the dorsum, and finely pilose. The apical margins of

all except the last segment have elevated subapical chitinous rings which

are frequently provided, especially in the terminal segments, with a

number of short, heavy setae. The apical margin of the tenth segment

may bear a long spine at the apex (Fig. i lo), or the apical margin may
have a long, subapical, blunt process (Figs. i66, 167), or it may be

simply emarginate. The sterna are narrow transversely, with the

exception of the first two and the last two, and are more or less hidden

by the margins of the terga. The first sternum (Figs. 40, 42) is

usually subtrapezoidal with the cephalic margin concave. The second

sternum of the male is developed into an accessory copulatory appara-

tus which will be described later. In the female this sternum is sim-

ilar to sterna three to eight and consists of an oblong plate of chitin,

slightly wider cephalad, and having small ental projections at the ceph-

alo-lateral angles. The eighth sternum of the female is divided into

three sclerites (Figs. 109, 116), a single large proximal one and two
small, sometimes obsolete, ones which are intimately connected with

the first pair of gonapophyses. The ninth sternum (Figs. 109, 116)

is greatly reduced in the female, being represented by narrow sclerites

along the margins of the tergum extending from the proximal end to

about the distal third or half of the segment. The ninth sternum of

the male bears the genital opening, and on each side of this, and cov-

ering it, there is a more or less oval plate. These plates are known
as the parameres (pa. Figs. 118, 121, 147, 165, 171, 172, 183). The
tenth sternum is fused with the tergum on the lateral aspect.

Abdominal Appendages.—This term includes the accessory gen-

italia and anal appendages of the male, and the ovipositor of the

female.

Accessory Genitalia (Figs. 33, 97, 98, loi, 105, 107, 108, 120,

122).—The accessory genitalia of the male are derived from the sec-

ond and third sterna, and a portion sometimes from the second tergum.

The sperm duct opens in the ninth sternum and spermatozoa are trans-

ferretl to the accessory pouch or vesicle by doubling the abdomen upon



487

itself. The sternum of the second segment forms two heavily chi-

tinized hamules (Fig. 33, hm) which serve as covering plates. The
membranes immediately below these form a sheath for the penis (Fig.

33, ps). The latter is very heavily chitinized and is bent entad, extend-

ing to about the middle of the abdomen, and at the ental end are at-

tached heavy muscles which operate the organ. The tip of the penis

is largely membranous and flexible, and exhibits modifications which

appear to be of specific value in classification, at least in some genera.

The tip fits behind a heavy cephalic projection of the third sternum,

the seminal vesicle, when not in use (Fig. 33, sv). Small knob-like

projections may be seen extending ventrad from the lateral margins

of the second tergum and just caudad of the hamules. These are fre-

quently concealed in the Zygoptera but are large and conspicuous in

the Anisoptera where they are known as the genital lobes (Fig. 33, gb)

.

The cephalic third or less of the third sternum is elevated, heavily

chitinized except at the tip, and extends some distance cephalad of the

cephalic margin of the segment. In a few Anisoptera this part is re-

ported as functioning as the penis, the parts already described for

Zygoptera being unimportant.

The variations occurring in this organ throughout the suborder are

marked and are in all cases of generic rank as diagnostic characters.

In closely related specific groups, however, it can not be relied upon,

and recourse must be had to the anal appendages.

Anal Appendages (Figs. 34, 38, 109; aas, aai).—At the caudal

extremity of the abdomen of the male. there are always four appen-

dages; an upper dorsal pair, the superiors (aas), and a lower, the in-

feriors (aai). Of these, the upper is more often the longest, but it

may be reduced and shorter than the ventral pair. The anus opens

between and slightly dorsad of the bases of the mesal lobes of the

ventral pair. The dorsal pair of appendages is frecjuently forcipate,

and the tips are often contiguous and sometimes have between their

bases a knob-like projection.

Ovipositor (Figs. 109-116).—The ovipositor of the female con-

sists of three pairs of valves or gonapophyses. The ventral, mesal

pair are slender and heavily chitinized, and are transversely ridged at

the tip and usually provided with a saw-tooth edge. The cephalic pair

of gonapophyses (oce) is derived from the eighth segment ; the median
pair (not shown in the figures) and the broad caudal pair (oca) from
the ninth segment. The caudal pair of gonapophyses differ much in

shape from the cephalic and median pairs. They are very broad at the

base, somewhat contracted at the apex, and bear short, chitinized,

curved subapical rods, the prostyles (prs). The ventral margins of



43S

the caudal valves are always serrate.

Variations in the ovipositor of the female are seemingly of little

importance in classification although there is enough difference in the

apical, sternites (stis) of the eighth segment alone to facilitate the sep-

aration of genera.

Life History and Habits

The metamorphosis of all Odonata is incomplete and the life his- .

tory relates to the egg, nymph, and adult.

EGG

The eggs of Zygoptera are elongate and ovoidal, their length being

much greater than their transverse diameter. In length they average

about one millimeter; in diameter usually about one-fourth of this.

They are inserted either above or below the surface of the water in

the stems of plants. Lestes and related genera insert the eggs con-

siderably above the level of the water, and several instances are re-

corded in which the plants suffer from excessive oviposition. Most
of the Coenagrioninae oviposit beneath the water upon the submerged
parts of plants. To accomplish this, the female with the male clinging

to her alights on a projecting part of a plant and backs down into the

water dragging the male with her. She often goes so far beneath the

surface that both are completely submerged. Kellicott ('99:24)
observed the females oi Argia mocsta putrida descend into the water

in this fashion ; and I have frequently seen Biwllagnia signatmn de-

scend into the water to oviposit and, less frequently, Ischmira vcrticalis

and Bnallagma antcnnatiun. It is probable that many more of the

subfamily Coenagrioninae enter the water to find a suitable place for

oviposition. The egg-laying habits of the Agrionidae have not been

extensively studied; but Kennedy ('15:339) reports that Agrion

acqiiabilc variety yakiina deposits the eggs beneath the surface of the

water upon willow roots, and is unaccompanied by the male. Need-

ham also says that Agrion maculatum oviposits just beneath the sur-

face of the water, but Wesenberg-Lund ('13) observed a European
species depositing eggs above the water. In all cases the female was
unaccompanied by the male.

The number of eggs laid by a single female has been but partially

investigated, owing to the great difficulty of inducing the female to lay

in captivity. A number of adults were dissected with a view to discov-

ering the egg-laying capacities of the group. Several reared specimens

which had no chance to deposit eggs were found to contain as many



439

as looo ova but only 60 or 70 of them were of normal size and con-

sidered mature. Another female, Ischnura verticalis, contained 203
mature ova, while a third teneral female of Bnallagma hageni con-

tained 290 mature ova. Calvert ('93) says that the average dragon-

fly probably lays between two and three hundred eggs, and this state-

ment seems to coincide with that above.

The length of time spent in the e:gg stage is also imperfectly

known. Lucas ('00: 18) reports that Sympetrum striolatum spends a

month in this stage. Bal four-Browne ('09:256) says that eggs of

Ischnura clegans and Bnallagma pulchellwn, laid at the beginning of

August at East Norfolk, England, required from four to five weeks

to develop. The temperature relations are not mentioned, but it is

probable that this period varies to some extent. Needham ('03) calls

attention to the fact that the eggs of Lestes, which are laid above

water late in July, develop to a certain point, apparently ready to hatch,

and await submergence before eclosion. The water does not reach

them until late in fall ; and this means that at least several months are

spent in the ^gg stage. Brandt ('69) reported the development of

Agrion (Caloptcryx) virgo in three weeks during a hot summer.

In the final stages of embryonic development the head is directed

towards the small end of the tgg. This end is always nearest the

cuticle of the plant, and the nymph consequently emerges head first.

NYMPH

Grozvth.—Immediately after hatching, the nymph is helpless and
unable to move about actively. In this condition it is known as the

pronymph (Balfour-Browne, '09:258). A few minutes afterward the

skin of the pronymph splits and the true nymph escapes. During the

second nymphal stage the nymph is a minute insect, hardly longer than

the egg from which it hatched. The antennal segments are three

and there are no wings or sexual appendages. From this stage the

nymph grows and molts at intervals, the time between molts depending
largely upon the temperature and the amount of food which it is able

to capture. The antennae increase in number of segments until six

are present, in which condition they remain until the last nymphal
stage, when there are seven. The wings appear as ridges during the

fourth stage, but the sexual appendages do not appear until the seventh

stage, according to Balfour-Browne ('09). This seems to be contra-

dicted by the rather frequent observance of nymphs without wing-cases

and fairly well-developed appendages. There is great variation in the

time between molts, due primarily to temperature. It often happens



440

that when nymphs are brought into the warm laboratory they molt

within a few days. Balfour-Browne found surjirising differences in

the time between molts in nymphs kept at constant temperatures, so

that it would seem probable that other factors enter into the problem

besides temperature. He was able, however, to reduce the length of

the stages by raising the temperature, and found that in some cases

these lasted, in low temperatures, for 150 days, while in others they

lasted only five days at higher temperatures. The number of molts

varies from ten to fifteen in the Coenagrionidae, and the length of the

nymphal life may range from 229-624 days (Balfour-Browne, 'og).

Habitat.—In nature, the nymphs are most often found hiding

among the weeds and rubbish along the margins of lakes, ponds,

and streams. A few have been taken under rocks in swift currents,

among them Argia putrida (Needham, '03) and Argia tibialis. The
Agrionidae frequent the swifter currents, and seem to prefer these

situations to any others. They are never found in stagnant ponds.

Nymphs of Lestes, on the other hand, do not occur except in stagnant

woodland pools, and are never taken along the banks of streams unless

a stagnant condition is present. They prefer the shade, and hide

among the broad-leaved types of small water-v^^-eeds, being rarely found

among the narrow-leaved rushes and saw-grass. Riley ('12) says

that the nymphs of Zygoptera react negatively to light from a pro-

jection lantern but that such a reaction is often inhibited by the habit

of clinging to objects. He was unable, however, to obtain similar

reactions to moderately strong daylight. Reactions to heat have not

been studied, but the nymphs are able to withstand temperatures near

the freezing-point and may be collected during the winter from be-

neath the ice. They readily succumb when the temperature of the

water rises much above 70°P., but flourish well at 66.2°F. or I9°C.

(Balfour-Browne, '09). Lestes is particularly sensitive to high tem-

peratures, and when in captivity considerable care must be taken to

keep the temperature low enough for them.

Food.—The food of the nymphs consists almost entirely of Crus-

tacea, the larvae of nematocerous Diptera, such as mosquitoes and

chironomids, and ephemerids. Very young nymphs have been known
to thrive on Paramecium and other Protozoa. Of a large number of

Lestes which were dissected, nearly all contained Daphnia and Cyclops,

while the coenagrionines dissected contained many heads of chirono-

mids and only occasionally small Crustacea. However, a single small

Ischnura verticalis nymph contained eight specimens of Daphnia, and

it seems highly probable that other insects are also taken when the

normal food supply is scarce. Diatoms and other minute organisms



441

are frequently found in the alimentary tract, but this is due to the fact

that other insects have been eaten which feed upon these organisms.

The following is a list of the kinds of food known to be eaten by
zygopterous nymphs.

Protozoa Paramecium.

Crustacea

Copepoda . . . Cyclops.

Anemopoda . . . Daphnia.

Arthropoda
Arachnida . . . Hydrachnidae (rare).

iDiptera—Chironomidae, Culicidae.

Odonata—Zygoptera.

Ephemerida—Ephemeridae.

Vertebrata Very young fish.

Color Adaptations.—In almost any collection of live zygopterous

nymphs, there will be found brown and green individuals of the same
species. When collected from localities with abundant green vegeta-

tion, nearly all the nymphs will be green ; when taken from situations

where little green vegetation occurs, the nymphs are brown or dark

in color. Furthermore, as has been observed in rearing specimens,

green nymphs placed in a jar without green plants become brown after

a few molts, and thus seem to be able to adapt themselves to the color

of the surroundings. The color of the nymph, contrary to what might
be expected, seems to have no influence upon the color of the adult.

Enemies.—The nymphs of Zygoptera are preyed upon by a number
of enemies, the most formidable of which are fishes. Forbes ('88)

reported that odonate nymphs formed ten to thirteen per cent, of the

food of Perca flavcscens—the common perch, Aphredodcriis sayamis
—the pirate perch, and Pomo.xis annularis, the crappie ;and twenty-five

per cent, of the food of the grass pickerel, Esox vermicidattis. Riley

('12) says that Lepomis gibbosus, a common sunfish, and the yellow
perch, Perca flavesccns, commonly feed upon agrionid (coenagrionid)
nymphs.

Among the predaceous aquatic Hemiptera, the genera Ranatra,
Belostoma, and Notonecta, and probably others, feed upon the nymphs.

A mite, Arrlicnurus sp., is a common external parasite of the

nymph. At the time of emergence of the adult, the mite migrates from



442

the nymph to the adult and is carried about by the latter until it is

nearly mature, when it escapes again into tiie water for tiie final stage.

Another mite has been reported to feed upon the eggs of Anisoptera,

but this statement has not been verified for the Zygoptera. Needham
('03) says that a large number of hymenopterous parasites prey on
the eggs of Lestes, left exposed above the water-line, and he reared

the following species: Brachista pallida Ashm., Ccntrobia odonatae

Ashm., and Polynema ncedhami Ashm. Brandt ('69) also reports

-

rearing Polynema oviiloruui from the eggs of Agrion (Calopteryx)

and says that as many as fifty per cent, of the eggs were sometimes

destroyed by this parasite.

A fungus belonging to the Saprolegniales frequently attacks the

nymphs, especially if enfeebled from any cause. Sometimes it be-

comes very difficult to rear specimens, and if the rearing-jars become
infected nothing short of thorough sterilization will be of any avail.

This fungus is related to the one attacking fish and causing great

damage in hatcheries. It is also known to attack the larvae of Coryd-

alis.

Emergence of Adidt.—When the nymph has molted a stated

number of times, somewhere between ten and fourteen, and has be-

come full-grown, it crawls out of the water, dries its cuticle, which

soon splits along the mid-dorsum of the thorax and head, and the

adult emerges. The nymphs of Zygoptera usually seek the sunlight

to transform and emerge early in the morning, the greater number
being clear of the skin before eight o'clock. A much smaller num-
ber have been seen to emerge after six o'clock in the evening or late

in the afternoon, but very few, if any, emerge during the heat of the

day. The emergence follows a more or less definite schedule. When
first out of the nymphal skin, the parts of the body are no larger than

the parts of the foregoing nymph, and the insect is yellowish green

in color. Great changes soon begin, including an elongation of the

abdomen and wings as well as enlargement of other parts, and within

an hour the insect is ready to take flight. At this time it may show
mature coloration or the color may still be incompletely developed,

and in this condition the adult is known as teneral. The teneral state

may last for several days or longer, depending somewhat upon the

amount of sunlight to which the insect is subjected, or there may be

no further change after the power of flight is attained. Enallagma
cxsulans, B. gctninahtm, and the male of Ischnura rcrticalis are e.x-

amples of species which apparently have no teneral state. Enallagma
caruncidatum, and Ischnura vcrticalis, female, are examples of spe-

cies which apparently have a long teneral period. The change from



443

teneral to full adult coloration is a phenomenon which is not well

understood. Just why the thoracic stripes of Bnallagma signatum,

for instance, should change from a pale but distinct blue to a bright

orange in the course of development, while the stripes of the same
region in Lcsfcs rcctangiikiris change from a dull brown to pale blue,

is impossible to explain without a more thorough knowledge of the

chemical nature of the pigments which undergo the changes.

The following observations were made upon the emergence of

Ischnura zrrticalis. The rate of development is approximately simi-

lar to that of all Coenagrionidae. The rearing-jar was kept in the

laboratory on the west side of the building and hence did not get the

early morning sun. This accounts for the late emergence of the

nymph.

9 :30 A. M. The nymph crawled out upon the weeds within the

jar and seemed about ready to emerge. The nymph when removed
v.'as dissatisfied and restless and tried to get a firm hold on something

with its claws.

9 :35. Body nearly dry.

9:45. The thora.x suddenly splits and the insect rapidly emerges

from the skin ; color mostly light green and pale yellow ; dorsal por-

tion of the eyes dark; sides of the thora.x darker.

9:50. Clear of the skin; wings 4 mm. in length, abdomen 10

mm.
;
general color becoming darker

;
greens becoming brown ; wings

increasing in length; insect restlessly moving about on the support.

9:55. Eyes plainly striped with brownish bands; abdomen 11

mm. in length, wings 4 mm. ; wings suddenly elongating near the

proximal end.

9 -S?- Wings 7 mm. in length.

10:00. Wings 8 mm., abdomen 12 mm. in length.

10:01. Wings 9 mm., abdomen 12 mm. in length.

10:03. Wings II mm., abdomen 12 mm. ; wings pale light green,

thorax and head brownish green ; abdomen pale green at base, darker

at apex.

10:06. Wings 13 mm., abdomen 12 mm.
10:07. Wings 15 mm., abdomen 12 mm.
10:09. Wings 15 mm., abdomen 13 mm.; abdomen suddenly

elongating at the base.

10:14. Wings 15 mm., abdomen 15 mm.
10:18. Wings 15 mm., abdomen 15 mm.
10:20. Wings 15 mm., abdomen 16 mm.
10:24. Wings 16 mm., abdomen 20 mm.
10:28. Wings 16 mm., abdomen 24 mm.



444

10:30. Wings 16 nun., :il)cl(jincn 24 mm. Thonix grayish green;

abdominal segments two to six nearly transparent; wings becoming
transparent ; stigma faint, hardly noticeable.

10:35. ^'' increase in length of the abdomen or wings; abdomi-

nal segments becoming dark near the sutures; stigma of the wings

darker, now plainly noticeable ; thorax olive-green
;
pronotum black.

10:40. First two segments of the abdomen dark green; segments

three to six pale green, the apical segments the same as the proximal

ones; thorax becoming steadily darker; first trial of the wings; the

insect is nearly ready to fly.

10:45. Fidly al)le to fly, but still delicate and without full adult

coloration ; no further increase in size of the abdomen or wings, but

growing steadily darker in color and indications of permanent adult

coloration becoming evident.

10:55. Stripes of the thorax very distinct, though no blue or

other bright color has appeared ; very active and using its wings fre-

quently.

12:00 M. Not yet fully colored, the two apical segments of the

abdomen beginning to show blue ; the thoracic stripes of green not

fully developed.

2 :oo P. M. Postocular spots distinct ; dorsum of abdominal seg-

ments eight and nine sliowing signs of the blue coloration.

3 :oo. Insect fully colored and perfectly developed in ever}^ way.

ADULT

Habitat.—The adult Zygoptera are most frequently encountered

flving along the streams or about the lakes, ponds, or marshes in

which the nymphs abound. Lestes is a frequenter of the tliick woods
near woodland marshes ; Hetaerina and Argia are most commonly
encountered near rapid streams, while the remainder of the Illinois

representatives of the suborder may usually be found near small

lakes, ponds, or sluggish streams.

Flight.—The fliglit is slow and uncertain, though frequently rapid

enough to enable the insect to avoid the collector with surprising regu-

larity. The vibration of the wings is much slower tlian that of the

Anisoptera, and is more like that of a butterfly.

Mating Habits.—In .summer, pairs of Zygoptera may be fre-

quentlv found flying together. The male grasps the female just be-

hind the prothorax bv means of the anal appendages. The female

then doubles the body beneath the body of the male bringing the ovi-

positor in contact with the accessory genitalia of the second abdomi-



445

nal segment of the male. After fertilization of the female the two
continue to fly together and the female is refertilized at intervals

during the egg-laying period. At the time of oviposition the two

often remain together and the eggs are frequently laid while the pair

are still in copula.

The time elapsing from emergence to egg-laying is not known
with any certainty. The egg-laying period also, has been little

studied, but it is thought to last for several weeks.

Food.—Many records have been made of the destruction of mos-
quitoes by Anisoptera, but no one seems to have observed or at-

tempted to determine the feeding habits of the adults of Zygoptera.

Dissection of a number of specimens revealed the fact that the Zy-

goptera prefer small Diptera to most other food. Many remains of

nematocerous Diptera were found, as the following table will show,

but very few remains of other insects.

Name Food eaten Date of coll. Locality

1. Hetaerina amerieana, $ Hyiiicnoptera ( ?) Oct. — , 1915 Mimcie, 111.

2. Ischnura verticalis, 9 Diptera—abundant re- June 23, 1915 Havana, 111.

mains
3. Ischntira verticalis, g Alimentary canal empty June 2.3, 1915 Havana, 111.

4. Ischnnra verticalis, 5 Many .-mall Diptera June 23, 1915 Havana, 111.

5. Aryia apicali^, ^ Diptera—Nematoccra June —, 1915 Clear L., Ky.
6. Enallagma civile, ^ Diptera June 18, 1915 Urbana, 111.

7. Lestcs vigilax, ^ Diptera—Nematocera Bluffton, Ind.

S. Enallagma hageni, 9 Diptera—Nematocera July 18, 1915 Orono, Me.
9. Enallagma antennatum Diptera—Nematocera July 18, 1915 VrViana, 111.

10. Ischnnra verticalis Large number of butter- July 13, 1915 Lake Villa, HI.

fly scales

The most common food of the adult apparently consists of small

flies. No remnants were found which resembled mosquitoes, and the

hymenopterous insect reported is questionably identified as such. The
specimens of lepidopterous scales found in number ten were unmis-

takable, and it is, therefore, evident that other insects are sometimes
eaten besides Diptera*. They have also been reported to eat aphids.

Enemies.—The adult Zygoptera are troubled by few enemies of

any sort. Birds are perhaps the most important, but even these are

not to be considered as serious enemies. Several species of hydrach-

nid mites have been found attached to the adult, the most common of

which are species of Arrhenurus. The mites are often conspicuous

on account of their orange or reddish color, and large numbers often

attach themselves to a single individual. However, they seem to

cause the insect but little inconvenience.

•Poulton ('06) reports that both Ephcmeridae and Lepidoptera are sometimes
eaten.



446

History of thk Zygoptera

paleontology

The oldest records of insects which resembled Odonata are found
in the upjier Carlson! ferous. The wings are the only parts which are

well preserved, but these are very different from the wings of living

Odonata. The fossil species are termed Protodonata by Handlirsch

and are thought to be connected with the still more ancient forms, the

Paleodictyoptera, which are the most primitive of all fossil insects. The
features which distinguish the Protodonata from the Paleodictyop-

tera and link them to the true Odonata include the fusion of the

longitudinal veins at the base of the wing; the presence of numerous
orderly arranged cross-veins; the appearance of interposed veins or

sectors between the longitudinal veins; and, finally, the approxima-

tion of the wings themselves at the base. The protodonate wing,

however, differs from that of true Odonata in the lack of stigma and
nOdus and in the supposed absence of that typical feature, the cross-

ing of the radial sector over media. It is unfortunate that more of

the bodies of these interesting forms have not been preserved, for

it would be advantageous to know what types of head, thorax, and
abdomen they possessed.

The next remains of importance are found in the Jurassic Lias of

England and are much more closely related to living species than the

Protodonata. They are classed as Odonata and divided into two sub-

orders, the Anisozygoptera and Archizygoptera. There is a single

living representative of the Anisozygoptera in Epiophlebia (Paleo-

phlebia) of Japan, but the Archizygoptera have no living represen-

tative, and seem to be merely an offshoot from the Protodonata which

apparently disappeared after a short stay in geological history. The
archizygopterous wings show marked deviations from the original

type of the Protodonata, and a very near approach to some of the

zygopterous wings of today. The reduction in number of cells and
cross-veins is characteristic of both ancient and modern forms, but

the absence of the arculus and the separation of media and radius to

the very base of the wing, distinguish the fossil species from any
living forms. The Anisozygoptera have characters common to both

Gomphidae and Agrionidae, the oldest fossils being perhaps more
closely related to the Gomphidae. The wings have nodus and stigma,

and the radial sector plainly crosses the median vein. The degree of

obliquity of the c[uadrangle and the presence of many interposed

sectors between the longitudinal veins place them with the Agrioni-

dae. The head and the wings resemble those of Gomphidae in shape,



447

but the thorax and abdomen of the fossil suborder are variable and

resemble both families to some degree.

The true Zygoptera make their appearance in the Jurassic period.

The oldest of these, comprising the families Epallagidae and Stele-

opteridae, have been found in the lithographic quarries of Bavaria.

The majority of species from this source belong to the Epallagidae

and are fortunately in a good state of preservation. The wings are

not petiolate, the nodus and stigma are present, the nodus being situ-

ated near the middle of the wing and the stigma Ijeing long and nar-

row. There is an obliciue arculus and a more or less oblique triangle

;

the radial sector and the second median vein arise far distad of the

nodus ; and the costal field contains more than ten cross-veins proxi-

mad of the nodus. The abdomen is not greatly lengthened and the

legs are also normal in this regard. In the Steleopteridae the wing

is distinctly petiolate; there are about five antenodal cross-veins; and

the veins Mg and the radial sector arise proximad of the nodus. The
arculus and quadrangle are similar to those of the Agrionidae (Cal-

opterygidae). The family Steleopteridae is considered to be the

forerunner of the Coenagrionidae.

The Tertiary deposits furnish us with the next oldest representa-

tives of the group. True Zygoptera, Anisoptera, and a single family

of Anisozygoptera have been found in the Florissant of Colorado

and in the Tertiary deposits of Baden, Germany. Many of the species

are referable to extant genera. More than eleven genera of Zy-

goptera have been found in these strata.

The first nymphs to appear in the geological record are described

by Hagen from the Baltic amber and from the Tertiary of Rhein-

land and Baden, Germany. Many of these forms had caudal tracheal

gills and were apparently true Zygoptera. Scudder ('go) has also

figured and described a nymph from the Florissant which doubtless

belongs to the Zygoptera.

The following tabular summary gives the characters which have

been developed successively in the past, beginning with the family

Dictyoneuridae of the Paleodictyoptera from which the Protodonata

are thought to have been derived.



448

Tabulae Summary

Paleodictyopteea



449

Tabular Summary—continued

Paleodictyoptera
I

Protodonata
I

Odonata

Dictyoneuridae

Meganeui'iilac

Protagrionidae
Paralogiilae

Anisozygoptera

Archizygoptera

Zygoptera

Anisoptera

No quadrangle
triangles

or No quadrangle
triangles

Three simple anal

veins present

Anal field not exten-

sively developed

Head rounded ; of

considerable size

Not known

Not known

Not knovra

Not known

or Q u a d r a n gle and
sometimes trian-

gles present

Anal veins represent-

ed by a single

vein

Anal field not exten-

sively developed

Large numbers of

rows of cells be-

tween all longi-

tudinal veins, the

rows extending far

proximad

Not known

Not known

Not known

Not known

Not known

Anal veins repre-

sented by a single

vein

Anal field often ex-

tended, but not

, braced by loop

Decided reduction in

number of rows
and a decided re-

treat distad, leav-

ing but few rows
between the prox-

imal portions

Head rounded and
of e o n s i derable

size

Eyes dichoptic in all

families

Labium cleft

Abdomen s 1 e n der

occasionally swol-

len at tip; superi-

ors leaf-like or

forcipate

Inferior anal ap-

pendages separate

Quadrangle always
present ; triangles

sometimes present.

Anal veins repre-

sented by a single

vein.

Anal field extensively

developed or re-

duced ; when ex-

tended often
braced by loop.

Still further reduc-
tion and retreat

distad.

Head angular; often
widened.

Eyes dichoptic or
holoptic.

Labium cleft or en-

tire.

Abdomen s 1 e n d er,

Zygoptera, or

thickened, Anisop-
tera ; s u p e r i rs

leaf-like, forcipate,

or reduced to tu-

bercles.

Inferior anals fre-

quently united in

Anisoptera.



450

ONTOGENY

The various parts of the body will now be considered with ref-

erence to their form during the different periods of development.

Head.—The compound eyes during the life of the embryo are

small and dichoi)tic and situated on the lateral aspect of the head.

After eclosion they become larger, are sometimes exi>anded dorsad,

but never become holoptic until the adult stage. The embryonic an-

tennae are composed of three segments, the second segment being

longer than all the others together, and the third segment nothing

more than a spur at the tip of the second. The increase in number
of segments takes place by division of the second, which continues to

divide until the antenna has seven segments in all. There is little, if

any, variation in the diameter af the different segments of most
nymphal antennae, but the proximal segments of a few are sometimes
greatly developed and much larger than any of the distal ones. In

the adult antennae, the apical segments are setiform and the number
of segments varies from four to six. The labial palpi and the median
lobe are without setae or fixed hooks. The cleft is usually obliterated

after eclosion, but remains practically unchanged in the nymphs of

some species. The labial palpi of the young nymph are soon after

eclosion provided with fixed hooks, and the median lobe is furnished

with rows of setae. The adults have no rows of labial setae, but

these are scattered promiscuously over the surface. The condition of

the mandibles and maxillae is not known for the embryonic stages,

but the nymphal condition is much simpler than that of the adult. In

this stage the mandible is not biramous except in a few cases. The
adult mandible, however, is divided into two parts, one composed of

a number of teeth and the other of several cutting edges forming a

Z when viewed from the edge. The galea-lacinia of the nymphal
maxilla is not as specialized as that of the adult, which bears a greater

number of fixed hooks and setae.

Thorax.—The thorax of the embryo consists of three equal seg-

ments, each with a pair of appendages. Very little can be said of the

sclerites in the embryonic stages, but the segments of the nymph are

all about equal in size. The legs are widely separated and the in-

vaginations of all furcae are usually prominent. The suture sepa-

rating the proepimeron from the proepisternum is indistinct in the

earlier nymphal stages, but becomes more distinct with age. In the

mesothorax and metathorax, the interpleural suture is distinct in all

zygopterous nymphs and in the adults of the family Agrionidae. In

the Anisoptera it is indistinct in all stages. The infraepisterna and
supraepisterna are separated by furrows in the nymph, but there are

no definite sclerites formed until the adult stage. The mesonotum is



451

always divided in the nymph as in the adult, but seems to be simpler

in structure in the nymph. The mesostigmal plates of Zygoptera are

not developed until the adult stage, but the depressed area caudad of

the mesoscutum in the Anisoptera is frequently present in the

nymphal stages, especially in the Libellulidae. The nymph molts

several times after eclosion before the rudiments of the wings appear

as minute ridges on the dorsum of the mesothorax and metathorax.

They develop subsequently like the wings of heterometabolous insects

in general. As already noted, the crossing of the radial sector over

the media can not be followed, and in only one genus, Lestes, is there

any recognizable portion of the radial sector. The character of the

tracheation of the wing-cases of several zygopterous nymphs is

shown in Figui^es 14—17.

Abdomen.—A'ery little can be said of the abdomen except that in

both the embryo and nymph the segments are about equal in length

and more or less cylindrical. Reduction in size, lengthening of the

segments, and flattening of the abdomen, together with the appear-

ance of dorsal and lateral spines, seem to be the developmental ten-

dencies in the nymph. The accessory genitalia of the adult show no
signs of development until near the last nymphal stage, but the ovi-

positor of the female appears early, at least in the Zygoptera. This
organ undergoes great modifications and specialization in the adult

Zygoptera, but in the Anisoptera it is probably in the process of re-

duction and degeneration. The caudal tracheal gills of the Zygoptera
are present in the embr3-o, and at hatching they appear as cyhndrical,

jointed, cerciform appendages. Brandt ('69) says that at a still

earlier stage the lateral pair of gills are fused, but this observation

has not been verified. There is also a pair of smaller cerci dorso-

laterad of the lateral gills, making five caudal abdominal appendages
in all. All five of these are represented in the Anisoptera by short

cerciform appendages which are frequently triquetal and often

sharply pointed at the apex. It is important to note that these ap-

pendages are never united in the nymphs of Anisoptera or in Zygop-
tera, but that in the adults of Anisoptera the ventral pair is sometimes

fused. In all families of Zygoptera, the superior abdominal ap-

pendages, which replace the lateral gills, are greatly reduced, but in

some Anisoptera, family Aeshnidae, the lateral appendages are re-

placed in the adult by long, lateral, superior appendages resembling

gills. A fact which sheds light on the origin of the Odonata as a
whole, is the presence of lateral abdominal gills in the genus Cora of

Central America and Euphea of the Old World. The rectal gills of

Anisoptera have been thought to originate in the forms having tra-

cheae which anastomose on entering the walls of the rectum as in



452

most Agrionidae; but it is doubtful whether this fact is really im-
portant.

Some of the most interesting modifications of structure for com-
parison are found in the proventriculus. These were first investigated

by Ris ('96), who discovered interesting correlations between
the number of teeth and folds present and their supposed specializa-

tion in the different families. Conditions were simplest in the nymphs
of Agrionidae; more highly specialized in the Coenagrionidae, Aesh-
nidae, Gomphidae, and Libellulidae. The adult structures were much
more complicated than those of the nymphs of the same families.

The following table will suffice to show the important ontogenetic

tendencies of living forms.

Table showing Ontogenetic Tendencies of Ztgoptera

AS COMPARED WITH ANISOPTERA

Ego Nymph Adult

Anisoptera Zygoptera Anisoptera Zygoptera Ani-soptera Zygoptera

Eyes dichoptic Eyes dichoptic

Labium cleft

Labial p a 1 p us

without fixed
hooks

Median lobe

without setae

Labial palpi

without setae

Antennae with

three segments

Labium cleft

Labial p a 1 p us

without fixed
hooks

Median lobe

without setae

Labial palpi

without setae

Antennae with

three segments

Eyes dichoptic Eyes dichoptic

Labium s o m e-

times slightly

cleft, never
deeply

Mandibles not
divided at tip

Labial p a 1 p us

without fixed
hooks

Median lobe

with or with-

out setae in

rows

Labial palpi

with or with-

out setae

Antennae with
3-7 segments

Epicranial su-

ture traceable

Furcae of meta-
sternum often

indistinct

Interpleural su-

ture indistinct

Labium s m e-

times deeply
cleft

Mandibles a 1 -

ways divided

at tip

Labial p a 1 p us

with two fixed

hooks

Median lobe

with or with-

out setae in

rows

Labial palpi

with or with-

out setae

Antennae with
3—7 segments

Epicranial su-

ture traceable

Furcae of meta-
stcrnum never

indistinct

Interpleural su-

ture never in-

distinct

Eyes sometimes Eyes dichoptic.

dichoptic, usu-

ally holoptic

Labium s m e-

times slightly

cleft

Mandibles a 1 -

ways divided

at tip

Labial palpus
with one fixed

honk

Median lobe

with setae, but

not in rows

Labial palpi

without setae

Antennae with
4—7 segments

Epicranial su-

ture traceable

with difficulty

Furcae of meta-
sternnm c n -

cealed

Labium usually

deeply cleft.

Mandibles a 1 -

ways divided

at tip.

Labial palpus
with one fixed

honk.

Median lobe
with pctae, but
not in rows.

Labial palpi
without setae.

Antennae with
4-7 segments.

Epicranial su-

ture traceable

with difficulty.

Furcae of meta-
sternum c n -

cealed.



453

Table showing Ontogenetic Tendencies of Zygopteba

AS COMPARED WITH Anisoptera—Continued

Egg Nymph Adult

Anisoptera Zygoptera Anisoptera Zygoptera Anisoptera Zygoptera

Mesepisterna us-

ually separated

M e s e pisterna

a d j a cent or

separated

Abdomen cylindrical and about

equal in diameter throughout;

of the same diameter as the

thorax

No tracheal gills .Tracheal gills
but a long \ present

caudal projec

tion

M e s e p isterna

usually separat-

ed

Wing-cases un-

equal in size

Trachea of ra-

dial sector
crossing media

Venter flat-

tened, abdo-
men much
broader than
thorax

No tracheal
gills

Ovipositor d e -

veloped late or

wanting

Rectal gills
present

Folds of pro-

ventriculus : 4

large; 4 small

M e s e pisterna

a d j a cent or

separated

Wing-cases un-

equal in size

Trachea of ra-

dial sector not

crossing media

Abdomen of the

same diameter

as the thorax

Tracheal gills
present

Ovipositor d e

veloped early

Rectal gills ab-

sent

Folds: 4 large,

4 small; or 8

large, 8 small

M e s e pisterna

adjacent and
fused

Wings unequal

Radial sector

crossing media

Abdomen wid-

ened at differ-

ent points, us-

ually of small-

er d i a m e ter

than thorax

No tracheal
gills

Ovipositor some-

times well de-

veloped; us-
ually wanting

Rectal
absent

gills

Folds: 4 large,

and 4 small

M e s e pisterna

adjacent and
fused.

Wings unequal.

Radial sector

crossing media.

Abdomen equal

thro ughout

;

always of
smaller diame-

ter than tho-

rax.

No tracheal
gills.

Ovipositor a 1 -

ways well de-

veloped.

Rectal gills
absent.

Folds: 8 large,

and 8 small.

PHYLOGENETIC COMPARISON OF ZYGOPTERA AND ANISOPTERA

Several important theories and rules of procedure should be men-

tioned before undertaking a discussion of the suborders from a phylo-

eenetic standpoint. „ . . „ • j •

I,—Ontogeny repeats phytogeny. This is a well-recognized prin-

ciple and is the 'foundation of much phylogenetic work.

II—All testimony should be corroborative if properly under-

stood; or in other wo'rds, there should be no real conflict in the phylo-

genetic evidence obtained from different sources.



454

III.

—

The stem must be determined. Before an agreement can be

reached as to the phylogenetic status of any form, there must be

agreement as to what constitutes speciaHzation, and what generahzed

conditions. Suppose, for example, that within an order of insects

there are species with two types of wings—one having numerous

cross-veins and the other but few ; which is the more speciahzcd ? It

is possible for either type to have been derived from the other or

both to have arisen from a third extinct form. One may have be-

come specialized "by addition" and the other "by reduction". In this

case it is evident that the stem must first be determined beTore the

degree of specialization of either form can be stated with accuracy.

IV.

—

All possible characters should be taken into account, and a

decision concerning the rank of the group should be based on a study

of the whole organism. This method should be followed in view of

the fact that the same degree of specialization in structure is not

usually found simultaneously in different parts of the body, and it is

always to be preferred to the method of determining specialization

or generalization of a group of organisms by the study of a few

characters.

V.

—

TIic forces which produce modification in structure should

be recognised if possible and their effect upon structure determined.

In the following comparisons the various characters will be con-

sidered separately and, where possible, the stem form will be men-

tioned and the reasons given for so regarding it. For convenience,

the division of the suborders into families as outlined by Handlirsch

('o6-'o8) and Muttkowski ('lo) will be followed, the Zygoptera be-

ing divided into the Agrionidae and Coenagrionidae ; the Anisoptera,

into the Aeshnidae, Gomphidae, and Libellulidae.

Bgg

I.—Eggs of the Odonata are of two types; one long and some-

what cylindrical in shape, the other ellipsoidal and short. The dif-

ferences in shape are the result of different methods of oviposition.

The ellipsoidal form would seem to be the more primitive, judging

from a general knowledge of the eggs of various orders of insects.

No definite proof of this can be given, but a comparison with the

eggs of the Apterygota and the lower Arthropoda indicates that the

ellipsoid is probably the stem type. This is, however, in direct con-

tradiction to the argument found in the reduction of the ovipositor,

since the species with specialized or reduced ovipositors lay ellipsoidal

eggs. Disregarding the latter argument and considering the ellipsoi-



455

dal egg as the primitive type, the series from lowest to highest would

be something like the following: Libellulitlae, Gomphidae, Aeshni-

dae, Agrionidae, and Coenagrionidae.

Nymph

2.—The most striking differences in nymphal characters are

found in the shape of the body. Zygoptera are without doubt near-

est the primitive Campodea type, and Anisoptera show a marked
deviation which is possibly due to the habits of life. This interpreta-

tion is supported by the embryonic stage, in which the body shape is

essentially campodeiform in both suborders.

3.—The compound eyes of all forms are specialized, but the line

of descent is not difficult to follow. The primitive type is found in

the embryo, which has small circular eyes on the lateral aspects of

the head. The nearest approach to this is found in the eyes of zygop-

terous nymphs ; the farthest away from it, in the Anisoptera, where

the eyes show a tendency to become dorsal in position. The cause of

the modification is unknown, but may be due in part to their habits,

the Anisoptera being mud-inhabiting to a large extent and needing

eyes on the dorsum of the head. Another cause may possibly be

found in the accelerated development of the greatly enlarged eyes of

the adult. In respect to shape and position of the compound eyes,

then, the Anisoptera should be regarded as the more highly special-

ized group.

4.—The antennae show important lines of development. The
primitive antennae of the embryo consist of three segments, the sec-

ond segment being the longest. A great lengthening of the first seg-

ment is the main line of specialization, and this occurs only in

Zygoptera in the family Agrionidae. The antennae nearest the em-
bryonic type are found in the Gomphidae ; next in order are the

Aeshnidae, then the Libellulidae, and, finally, the Coenagrionidae and

the Agrionidae.

5.—The labium shows the more primitive condition in Zygoptera,

where the median lobe is deeply cleft in the family Agrionidae. Gra-

dations in complexity are found in a reduction in the depth of the

cleft, and the line of specialization may be followed through the fol-

lowing series, beginning with the least specialized : Agrionidae,

Coenagrionidae ; Gomphidae, Aeshnidae and Libellulidae.

6.—Mental setae are lacking in the embryo and also in the nympKs
of Aeshnidae, Gomphidae, Agrionidae, and a few Coenagrionidae.

The cause of the production of mental setae is unknown. There



456

seems to be greater specialization in the shape of the labial palpi or

lateral arms in tiie Coenagrionidae, notably the Lestinae, than in any
other group. The simpler types are found in the Aeshnidae, Gomphi-
dae, and Agrionidae, and a highly specialized form again in the L.ibel-

lulidae.

7.—The condition of the maxillae and the mandibles in species

existing prior to the present time can only be surmised, since there

are no embryological or paleontological data on the subject. These
appendages are so nearly alike in shape in the two suborders that no
comparison can be profitably made.

8.—The primitive prothorax, according to both paleontological

and embryological evidence, was a simple ring of the same size as

the mesothorax and metathorax. Specialized conditions are found in

the Anisoptera where, owing to the size of the head and the growth
of the compound eyes, the cephalic part of the pronotum is depressed.

The condition of the prothorax is probably primitive in Zygoptera.

The sclerites are not as distinct in the Anisoptera as in the Zygoptera,

indicating that obsolescense of tlie sutures has begun in this suborder.

9.—The next feature of note is found in the interpleural suture.

Stages of disappearance occur in all Anisoptera, the suture being

completely lost in the Libellulidae and perfectly distinct in all nymphs
of Zygoptera. The cause of this modification is unknown, but it is

probably due to the excessive development of the wing muscles with-

in the thorax. In respect to this feature, then, the primitive forms
are found in the Zygoptera; the specialized, in the Anisoptera.

10.—Another modification is found in the disappearance in the

Libellulidae of the metafurcal invaginations. The primitive condi-

tion or stem form is vmknown, as is also the cause of the disap-

pearance. It is probable, however, that the type with distinct in-

vaginations is the more generalized, which places the Zygoptera, the

Aeshnidae, and the Gomphidae much below the Libellulidae in position.

II.—In the shape of the wing-pads, the Anisoptera show more
conformity to the generalized types occurring in Plecoptera and Or-
thoptera than do the Zygoptera; and they must be regarded as gen-

eralized in this respect.

12.—The simplest abdomen, judging from embryological studies,

is a cylindrical portion of about the same diameter as the thorax.

The abdomen is much modified in all Anisoptera, where it is enlarged

and the venter flattened. The Zygoptera are generalized in this re-

spect, and a series showing progressive specialization in this single

feature would be as follows : Agrionidae, Coenagrionidae, Aeshni-

dae, Gomphidae, Libellulidae.



457

13.—The caudal tracheal gills of Zygoptera must be considered a

simple or stem character. This view is supported by much evidence

from embryological studies and the presence of one or two living

forms in which the gills are decidedly cerciform and cylindrical. The
modification into flat plates is undoubtedly specialization, but the re-

duction of the abdominal appendages in the Anisoptera indicates

further specialization of a different kind. Changes in shape of the

zygopterous appendages are probably due to a change from terrestrial

to acjuatic habits very early in the history of the group. If we con-

sider that the anisopterous appendage has been derived by progres-

sive reduction, the following should be the order of development

:

cylindrical cerci, flattened cerci, and reduction of cerci to short ap-

pendages similar to those in all Anisoptera. If, however, the gills be

regarded as derived from shorter caudal appendages, the Anisoptera

have the primitive types and the Zygoptera are highly specialized in

their elongate, flattened appendages. The presence of cylindrical

cerci as a primitive character seems to have the greatest amount of

embryological evidence to support it.

14.—The abdominal gills of Cora and Euphea of the Zygoptera

also afford comparative evidence as to the age of this suborder. Here
there are remnants of lateral, cylindrical gills on the abdominal seg-

ments. There seem to be embryological data sufficient to prove that

these lateral gills represent the appendages of forms more primitive

even than the Insecta.

15.—The oldest fossil Odonata showing ovipositors had the char-

acters of both Zygoptera and Anisoptera, and it is probable that the

stem forms had true ovipositors. The simplest type of ovipositor

among living Odonata is found in the nymphs of Zygoptera and
consists of a number of similar valves. The reason for the reduction

of the ovipositor in the adults of Anisoptera lies in the acquisition

of the aquatic habit and the consequent difficulty of depositing eggs

in plant tissue. It is reported that some Zygoptera do not insert the

egg in the plant but merely press it against the plant and allow it to

drop to the bottom ; and this appears to be a transition stage from
the endophytic to the exophytic method of oviposition. Reduction

of the gonapophyses, then, means specialization, and the order would
be—Zygoptera, generalized; Anisoptera, specialized.

Adult

16.—So many different lines of specialization seem to have taken

place in the development of the head capsule of the adult that it is



458

almost impossible to arrive at any conclusion as to its simplicity or

complexity. Suffice it to say that paleontological and embryological

data prove that there are primitive types in both Zygoptera and An-
isoptera. In the holoptic condition of the compound eyes, however,
there is a more definite character. As already stated, the primitive

type is dichoptic; and beginning with this condition, which we find

most closely approximated in the Zygoptera, there are all degrees of

dichoptic and holoptic states. The cause of the modification is prob-

ably due, in the adult, to the increased power of vision made neces-

sary by the greatly increased powers of flight and the fact that the

insect captures its prey while on the wing. An excellent series of

specializations is to be had in the following families, the Zygoptera
being the more generalized : Agrionidae, Coenagrionidae ; Gomphi-
dae, Aeshnidae, and Libellulidae.

17.—The antennae, as already noted, show marked reduction in

size from those of the nymphs. The nearest approaches to the primi-

tive, seven-segmented condition are found in the Libellulidae and
some of the Aeshnidae, where six segments are often encountered.

Most representatives of the remaining families have the segments

quite consistently reduced to four. The adults of the Agrionidae

have the most highly specialized antennae; and in a series showing
increasing specialization the Libellulidae would be the more gener-

alized. The following is such a series based upon antennal structure

:

Libellulidae, Aeshnidae, Gomphidae, Coenagrionidae, and Agri-

onidae.

18.—The front shows great deviation from the simpler forms in

the majority of the Anisoptera, and the mound-like elevation of this

part is characteristic of most families of this suborder.

19.—The mandibles of the adult have apparently undergone no
modification of importance in the different families. They are so

nearly alike in all groups that a comparison will not be attempted.

20.—The maxillae of the adult have likewise undergone little

modification in the different families, but the form nearest the primi-

tive type present in Plecoptera nymphs is found in the Gomphidae.
21.—The labium shows the same deviations from the primitive

condition as were described for the nymph. Looking upon the depth

of the median cleft as a measure of generalization, the Agrionidae

would be considered as the more generalized. Next in order are the

Coenagrionidae and, following these, the Aeshnidae, Gomphidae, and
Libellulidae. The lal)ial palpi retain about the same degree of

specialization that occurs in the nymphs; and the same sequence of

family specialization as has been described for the nymphs is present

in the adults.



459

22.—As regards the form of the microthorax, no stem can be de-

termined, but it is probable that there has been much more specializa-

tion in the Anisoptera than in the Zygoptera.

23.—The degree of complexity of the prothorax as a whole is

difficult to determine. Many sexual modifications occur in the adults

which must be considered as secondary characters having little bear-

ing on phvlogeny. The distinctness of the propleural suture, how-
ever, is of some value. In Zygoptera, this suture is most distinct in

the Coenagrionidae (Lestinae) and is moderately so in the Agrioni-

dae. In the Anisoptera it is most distinct in the Aeshnidae, but is

as a rule indistinct in other families. According to this character the

Zygoptera seem to be generalized; the Anisoptera specialized.

24.—In the mesothorax and metathorax the most important fea-

ture, aside from the wing structure, is to be found in the interpleural

suture. As already mentioned, this suture shows no sign of disap-

pearance in any of the nymphs of Zygoptera, and still remains undi-

minished in distinctness in the adults of the family Agrionidae. In

the Coenagrionidae, however, the interpleural suture becomes obsolete

in great measure. In both nymphs and adults of Anisoptera, it is

indistinct. The degree of its distinctness is therefore an excellent

character for determining the degree of specialization or generaliza-

tion of the species and consideration of this fact alone leads to the

conclusion that the Zygoptera are the more generalized.

25.—The varying degrees of approximation of the mesepisterna

and the metepimera indicate an entirely different line of development

from that shown in 24. The primitive condition is one in which the

two mesepisterna and metepimera are separated by considerable inter-

vals, as has been shown for the nymphs. The approximation of the

metepimera on the ventro-meson is a much later development and does

not appear until the adult stage. Nevertheless, nearly the same line of

specialization occurs as in the former case, the simplest conditions

being found in the Aeshnidae and the Agrionidae, the more complex
in the Gomphidae, Libellulidae, and Coenagrionidae.

26.—The development of the mesothoracic spiracles indicates that

the Libellulidae, again, are the most specialized, with the Agrionidae
and Aeshnidae at the bottom of the series. The size of the spiracles

in Libellulidae and the degree of their approximation on the dorso-

meson warrant this assumption, the primitive tvpes being small in size

and rather widely separated, as in Zygoptera and some Aeshnidae.

27.—A line of specialization is found in the length of the thorax

caudad of the metacoxae. In this the Coenagrionidae and Agrionidae
are decidedly the more specialized.



460

28.—More use li;is been made of the wings and wing venation in

following out genealogical development than of any other single por-

tion of the body of the dragon-fly. The evidence is conflicting in

many respects, and in coming to conclusions all characters must be

taken into account. The most noticeable feature of the wing venation

is the crossing of the longitudinal veins Rs and M. This condition

is so unique that it was doubted or denied for a long time, and not

until it was traced from its beginning in the tracheae of the nymph
was it generally accepted as true. Many of the changes in the wing
venation may be considered as the result of stress on particular por-

tions of the wing surface. The development has followed two lines

of specialization ; one of them a reductive process, exemplified in the

Zygoptera, the other additive, exemplified in the acquisition of im-

portant wing-braces in the wings of Anisoptera.

The main points regarding the specialization of the odonate wing
are stated in the following tabulation.

Generalized conditions

1. Wings of equal size and
venation.

2. Wings not petiolate.

3. Nodus not retracted

;

near the middle.

4. No reduction in number
of cross-veins.

5. Arculus near the base of

the wing.

6. No reduction in the

number of antenodals.

7. No reduction in the

number of postnodals.

8. Rs traceable throughout

its course.

9. Mo not arising distad of

the nodus.

10. Rs separating from Mg
near the nodus.

DcvclopJitcnfal tendencies

Wings of unequal size and
venation.

Wings petiolate.

Retraction of the nodus to-

wards the base.

General reduction in number
of cross-veins.

Retreat of the arculus distad

from base.

Reduction in number of an-

tenodal cross-veins.

Reduction in number of

postnodal cross-veins.

Rs not traceable throughout

its course. '

.

M2 arising distad of the

nodus.

Rs separating from Mo dis-

tad of the nodus.

^&3
13 O

a, o

m a,



461

Generalized conditions

11. Quadrangle triangular.

12. M3 and M4 not uniting

distad of the arculus.

13. Media at the top of the

arculus.

14. No development of the

anal loop.

15. No matching of the

transverse cross-veins.

16. Pentagonal cells numer-
ous.

17. Little reduction in the

number of rows of

cells and little retreat

distad.

18. Nodus and arculus not

approximated.

19. Stigma long.

20. Stigma sometimes ab-

sent.

Developmental tendencies

Quadrangle rectangular.

Mg and M4 uniting distad of

the arculus.

Media descending the arcu-

lus.

Development of the anal

loop.

Matching of the transverse

cross-veins.

Reduction in number of

pentagonal cells.

Reduction in the number of

rows of cross-veins be-

t w e e n all longitudinal

veins and retreat distad of

the rows.

Approximation of the nodus
and arculus.

Stigma short.

Stigma always present.

o-l



462

of the segments has been reduced as compared with that of the thorax.

In the Anisoptera there are other modifications besides the reduction

in diameter. Here, the abdomen is sometimes triangular in cross-sec-

tion, and different portions of the abdomen of the same species have

different diameters. Considering shape alone, the following line of

development may be recognized, beginning with the more generalized :

Agrionidae, Coenagrionidae, Aeshnidae, Libellulidae, and Gom-
pliidae. This order of specialization is followed throughout in the

abdomen.
30.—The appro.ximation of the terga on the ventro-meson, is a

mark of specialization most frequently found in the Anisoptera, as is

also the appearance of the secondary ridges on the terga.

31.—The anal appendages of the abdomen are interesting, and

the line of specialization indicated by them seems to coincide in general

with that already outlined for the suborders in 29 and 30. The series

has already been given for the two groups in paragraph 13. Within

the Anisoptera, two different lines are found, both probably represent-

ing specialization. In one of these the inferiors are fused, as in the

Libellulidae; in the other the superiors are enlarged and expanded, as

in the Aeshnidae. In the Zygoptera the forcipate appendages of the

Agrionidae probably represent the most primitive forms, and the short

and frequently greatly modified appendages of the Coenagrionidae, the

more highly specialized.

32.—Accessory male genitalia of the second segment are important.

The statement that this organ has been derived from the sexual organs

of the progoneates is substantiated by the reported connection of the

proximal end of the penis with the visceral cavity. This occurs in

Zygoptera and seems not to have been observed in the Anisoptera,

the connection supposedly having been lost through specialization.

Further specialization has been suggested in the tracheation of the

appendages, which occurs in some Anisoptera according to Backhoff

('10) but not in Zygoptera. Other differences indicating specialization

in Anisoptera are to be noted in the segmentation of the penis and.

in the position and connection of the seminal vesicle with the latter.

The structure of the hamules and the genital lobes, and of the portions

of the genitalia arising from the third abdominal segment, seems to be

simpler in the Zygoptera and not so much reduced or changed from

the original plan of the sterna of these segments. The tip of the intro-

mittent organ is much simpler in structure in the families of Zygoptera.

33.—As mentioned in paragraph 15, the presence of the ovipositor

in the early stages of the nymphs of Zygoptera and its absence in the

nymphs of Anisoptera suggest that the anisopterous appendages have



463

been reduced from a primitive form similar to that of Zygoptera. This,

together with the evidence furnished by extinct species vi^here adults

with wing venation similar to that of the Anisoptera had ovipositors,

proves fairly conclusively that the extant species without ovipositors

have undergone specialization by reduction.

34.—One of the most complete lines of specialization has been de-

termined by Ris ('96) for the structure of the proventriculus. He
found what he considered a primitive condition in the Zygoptera

(Agrionidae) in which there are sixteen internal folds. Specializa-

tion takes place by reduction, and there are eight folds in the Lestinae,

four in Gomphus and Aeshna, and none in Libellulidae, there being

instead four large symmetrical teeth.

35.—Specialization among the Anisoptera seems to be still further

indicated by the habits of the group, especially their habits of migra-

tion. The mere fact of migration is not important ; but the method
of flying in companies and particularly of so flying that there are reg-

ularly spaced intervals between the individuals is something which, if

true, is unique in this order and in the class Insecta.

Considering the preceding characters as a whole, it will be found

that there are two orders of specialization which apparently proceed

in opposite directions. One of these begins with the Agrionidae of

tiie suborder Zygoptera and ends with the Libellulidae of the Anisop-

tera ; and the other begins with the Libellulidae and ends with the

Agrionidae. The characters mentioned in the various paragraphs

will now be assembled for a comparison of the number of generalized

features in each family. The families are listed below, and are usually

or frequently generalized in the characters discussed in the paragraphs

the numbers of which are placed opposite.

Agrionidae.—2, 3, 5, 6, 8, 9, 10, 12, 13, 14, 15, 16, 18, 21, 22,

23, 24, 25, 28, 29, 30, 31, 32, 33, 34, 35.

Coenagrionidae.—2, 3, 5, 8, 9, 10, 12, 13, 14, 15, 16, 18, 21, 22,

23, 24, 26, 29, 30, 31, 32, 33, 34, 35.

Aeshnidae.— i, 4, 6, 10, 11, 15, 17, 25, 27, 28.

Gomphidae.— i, 4, 6, 10, 11, 17, 20, 27, 28.

Libellulidae.— i, 11, 17, 27, 28.

From this it will be seen that the most generalized family is the

Agrionidae. The evidence is such that it can not be doubted, and
it points to some form of the Agrionidae or related family as the stem

type. The following genealogical tree, based partly on Handlirsch

('o6-'o8), has been constructed after taking into account all existing

evidence. Distance to the right indicates specialization; vertical dis-

tance, time.



464

> > o

Eras Periods



465

been reported from Illinois ; and those with two have been collected

by the writer or seen in collections actually made within the state.

**Agrion acqitabile (Say)
**Agrion maciilatinn Beauvais

**Hetaerina americana (Fabri-

cius)

**Hetaerina titia (Drury)
*Lesics congener Hagen
*Lestcs disjnnctus Selys

Lestes eurinus Say
**Lestes forcipatiis Rambur
*Lestcs inacqualis Walsh

**Lestcs rectangularis Say
**Lestcs uncatiis Kirby
**Lestcs nnguiciilatus Hagen
**Lcstcs vigilax Hagen
**Argia apicalis (Say)
Argia fiimipennis (Burmeis-

ter)

**Argia moesta piitrida (Hagen)
*Argia sediila (Hagen)

**Argia tibialis (Rambur)
**Argia znolacea (Hagen)
**Enallagma antennatuni (Say)

*Enallagma aspersuni (Hagen)
**Enallagma calverti Morse

**Biujllagtiia caritnculahtni Morse
**Bnallagiua ciinle (Hagen)
Bnallagma cyathigerum (Char-

pentier)

Bnallagma divagans Selys

Bnallagma douhledayi Selys

**Bnallagma ebriuni (Hagen)
**Bnallagtna exsidans (Hagen)
**Bnallagma geminatumK.t\\\c<:>\.t

**Bitallagma liagcni (Walsh)
Bnallagma piscinarium W i I

-

liamson

**Bnallagma pollutum (Hagen)
**Bnallagnia signatmn (Hagen)
**Enallagnia traznatum Selys

**Nchalcnnia irene Hagen
**Amphiagrion saucium (Bur-

meister)

**Chromagrion conditum (Ha-

Ischnura kcllicotti Williamson

**Isc!iuura posifa (Hagen)
**Ischnura vcrticalis (Say)
*'*Anoinalagrioii hastatum (Say)

The division of the suborder into families and the arrangement

of genera followed by Muttkowski ('lo) have been adopted and are

herewith reproduced, including only the genera that occur in Illinois.

Family

Agrionidae
{

Coenagrionidae

Subfamily

Agrioninae

Lestinae

Coenr.grioninae

{

Genus

Agrion
Hetaerina

Lestes

Argia
Enallagma
Nehalennia

Amphiagrion
Chromagrion
Ischnura

Anomalagrion



4G6

In the following descriptions "length" refers to the length of

tlie body without appendages, and does not include caudal gills, anal

appendages, or antennae. In the color descriptions, where suitable

material was at hand, the colors were matched with colors given by
Ridgway in his "Color Standards and Color Nomenclature" ('12),

and the names of colors which appear in parentheses are from tliat

author.

Family AGRIONIDAB

The nymphs of this family are easily distinguished from those

of the Coenagrionidae. The three-sided gills, the deeply cleft median
lobe of the labium, the large basal segments of the antennae, the un-

equal length of the gills, and the heavy and sprawling appearance of

the legs are characteristic.

The adults are, as a rule, bright or strikingly colored, such colors

as metallic green and carmine being common. A large number of

antenodal cross-veins between costa and subcosta and the presence of a

distinct interpleural suture are also diagnostic*

Subfamily AGRIONINAE

Key to Genera

NYMPHS

a. Median cleft of median lobe of labium extending proximad of the

articulations of the labial palpi ; body color usually dark Agrion.

aa. Median cleft not extending proximad of the articulations of the labial

palpi ; body color usually light Hetaerina.

ADULTS

a. Wings with the basilar space, cell first M, without cross-veins ; meta-

pleural suture only with a pale stripe Agrion.

aa. Wings with a basilar space provided with cross-veins ; mesopleui-al,

interpleural, and metapleural sutures with pale stripes. . . .Hetaerina.

Genus Agrion Fabricius

In the nymph the median lobe of the mentum is provided with a

deep cleft which extends far proximad of the articulations of the

*Only one genus in this family is known in which the interpleural suture is

not well developed, and since that genus does not occur in the United States, this

character has been included in the family description.



467

labial palpi. The caudal gills are dark, with a light transverse band

about the middle of their length. The caudo-lateral margins of the

head are elevated to form a short, sharp tubercle. The nymph of but

one species has been available, and a study of this, together with a

comparison with Hetaerina, has afforded possible generic characters.

The adults are uniform in color, usually dark metallic green or

blue,- and black, and the wings are broad, with a large number of

cross-veins, the basilar space, however, being free from them. The

legs are provided with a double row of ventral setae which are usually

several times longer than the spaces between their bases.

Key to Species

a. Intersterniim metallic green ; wings of male smoky only on the apical

third; female with a sharp spine on the dorso-apical margin of the

tenth abdominal segment ; latero-ventral margins of thorax pale

aequabile.

aa. Intersternum entirely black ; wings of male wholly dark ; female with

only a short blunt projection on the dorso-apical margin of segment

ten ; latero-ventral margins of thorax dark maculatum.

Agrion aequabile (Say)

Nymph.—The nymph of aequabile has not been available for

study, but this species and its variety yakiina have been described by

Needham ('03:223,224) and Kennedy ('15:338). It seems to be

nearly identical with viaculatnm. The length of the basal segment of

the antenna is used by Needham for its separation from maculatum,

but this character can not be used for the separation of the variety

yakima. The length is somewhat greater and the gills somewhat

longer than those of macidatmn, but this character also is of doubtful

importance, and further study of the two species should be made to

determine the essential differences.

Adult; Male.—Color, metallic green and blue.

Head : mouth-parts black, median lobe of the labium triangular

in outline, basal segment of the palpus very broad, distal segment

small, cylindrical, longer than the fixed hook of the first; palpiger

about one-third the length of the first segment; antennae entirely

black ; clypeus and labrum black ; the front and genae metallic green

and thinly clothed with dark hairs.

Thorax metallic green, black and green below; pronotum with

the caudal margin entire, the caudal lobe convex and projecting caudo-

dorsad
;
proepimeron distinct ; cephalic portion of the prescutum large,



468

subtriangular, and depressed
;
paraptera subtriangular, each half with

the caudal margin sinuate and sHghtly emarginate on the lateral half;

intersternum green ; legs entirely black, the ventral setae much longer

than the distances between their bases, the setae of the front femora
twelve to fourteen in each row ; wings transparent, except the apical

third (Fig. 73), which is smoky, about one-third as broad as long,

slightly narrower than the wings of A. maadatum; stigma wanting,

antenodals of the front wing thirty-two.

Abdomen green and blue; sternum of segment ten and the apical

third of sternum nine buff-colored ; anal appendages (Fig. 117) mostly

black, the superiors wholly black, long and curved, tuberculate on the

lateral surfaces, and slightly emarginate on the mesal margins at the

middle; inferiors jjlack at the apex, paler at the Iiase, nearly as long

as the superiors, and provided with a minute apical point directed

mesad; parameres of the ninth segment small (Fig. 118).

Female.—Color, metallic green.

Head : proximal half of the second antennal segment with a pale

lateral spot ; labrum buff-colored on each side, and with a median hour-

glass-shaped black mark ; exposed portions of the mouth-parts, in-

cluding the mandibles and their trochantins, buff.

Thorax : latero-ventral margins pale, including the cephalo-

ventral margins of the mesepisternum, caudal half of the mesinfraepi-

sternum, a stripe along the metapleural suture extending more than

naif-way from the cephalic margin to the wing bases, and the ventral

and cephalic margins of the metepimera; intersternum green; wings

slightly smoky, but not darker on the apical third, stigma present,

white.

Abdomen metallic green and black, the apical portion dull and
paler below; tergum of segment ten with a prominent mesal ridge

which is produced into a long spine at the apex (Fig. no); anal

appendages consisting of conical superiors, double the length of the

blunt inferiors; ovipositor reaching to the middle of the tenth seg-

ment, the prostyles extending to its apex (Fig. no).

Measurements

Length, $ 49 mm.
Length, 9 44 mm.
Length of abdomen, $ 38 mm.
Length of abdomen, $ 34 mm.
Length of hind win^s, c? 32 mm.
Length of hind wings, 9 29 mm.
Width of hind wings, 3 9 mm.
Width of hind wings, 9 8 mm.



469

The species is apparently rare in Illinois though reported from

this state by Williamson ('oo). The above description was made from

three specimens in the collection of the Illinois State Laboratory of

Natural History, two of which bear the label "Mass.". I have not

seen the species within the state.

Agrion maculatum Beauvais

Nymph.-—Color, dark brown.

Head pentagonal, little contracted behind the eyes; eyes black,

a black stripe nearly the width of the eye extending to the caudal

margin of the head, and another stripe extending from the antennal

fossae to the eyes
;
proximal segment of the antennae thick, about as

long as the head, and usually slightly longer than all the remaining

segments together; labium with the median lobe deeply cleft, the

cleft extending proximad of the articulations of the labial palpi (Fig.

8) ;
proximal segment of the palpus with three immovable end-hooks

and two small setae near the base of the distal segment of the palpus.

Thorax : prothorax with a broad dark line on each lateral margin

which is continuous with the dark line on the side of the head; legs

slender, the femora with a whitish band on the apical third, with

a narrower brownish band proximad of the white one, and a distal

brownish band extending to the apex of the segment; tibiae without

heavy setae; tarsi short; wing-cases broad and extending in full-

grown nymphs as far as the fourth abdominal segment.

Abdomen subcylindrical, dark, and without distinct lateral keels;

apical margins of the terga with about four dark spots on the dorsum

;

lateral tracheal gills three-sided, somewhat blunt, with a white trans-

verse band near the middle of their length; median gill flat, shorter,

with a similar cross-band at the middle and another faint band beyond

;

marginal setae of the median gill long and slender, extending entirely

around the gill.

Measurements

Length 20 mm.
Length of abdomen 15 mm.
Length of lateral gills 10-12 mm.
Length of mctathoraeic wing-cases 6 mm.
Length of median lobe 4.5 mm.
Width of median lobe 1.3-3 mm.

Adult; Male.—Color, metallic green or blue.

Head green ; labium black, the median lobe subtriangular in out-

line, the cleft extending slightly less than half the distance from apex



470

to base; proximal segment of the labial palpus broad, Ijlack, the

palpiger short, about one-half the length of the first segment measured
from the point of articulation to the base of the second segment, the

fixed hook nearly as long as the distal segment of the palpus ; antennae

black ; clypeus and labrum metallic green or black ; front, together

with the clypeus and labrum, thinly clothed with black setae; eyes

black or slate-colored.

Thorax green above, black below
;
pronotum with the caudal

margins entire, the caudal lobe convex and projecting caudad and
dorsad; proepimeron distinct; cephalic portion of the mesoprescutum
subtriangular, depressed; dorsal carina distinct, black; paraptera sub-

cjuadrangular, the caudal margins emarginate on the lateral third;

metepimera broader adjacent to the wings; ventral portion of the

metepimera and the intersternum wholly black and subshining; legs

black, the setae also black and longer than the space between their

bases; anterior femoral setae fourteen or fifteen on each side; tarsi

black; wings very dark, almost opacjue, and about one-third as wide
as long ; stigma wanting ; antenodal cross-veins twenty-seven.

Abdomen nearly cylindrical, glabrous and fainth^ striated trans-

versely ; superior anal appendages long and black, the lateral surfaces

tuberculate, the mesal surfaces emarginate at about the middle; in-

feriors nearly as long as the superiors, straight and with a small apical

hook directed mesad (Figs. 139,139a).

Female.—Color, metallic green.

Head not essentially different from that of the male.

Thorax : wings pale brown, darker at the tips, transparent ; stigma

present, white; antenodal cross-veins 23 to 24.

Abdomen much shorter than that of the male; anal appendages
consisting of conical superiors more than twice the length of the blunt

inferiors; ovipositor (Fig. 109) with broad lateral valves reaching

about to the apex of segment ten, the prostyles rod-like and slightly

curved.

Measurements

Length, 5 46 mm.
Length, 9 41 mm.
Length of abdomen, S 38 mm.
Length of abdomen, $ 32 mm.
Length of hind wings, ,5 29 mm.
Length of hind wings, 2 30 mm.
Width of hind wings, S 10 mm.
Width of hind wings, 9 10 mm.



471

The nymphs of this species may be taken in the clearer and
swifter streams of Illinois, though not often in verj^ great numbers.

The adults do not wander far from the habitat of the nymphs and
their period of flight seems to be largely limited to a short time in

early summer. The species is supposed to have a northerly distribution,

but has been taken near the southern boundary of the state. Several

nymphs taken at Urbana early in June emerged June lo, 191 5, and
subsequent collections of adults show that the insect flies until early

fall, although the period of maximum abundance lies between the

middle of June and the middle of July.

Specimens have been seen from Havana, Muncie, Oregon, Peoria,

Urbana, Cook County, and McHenry County.

Genus Hetaerina Hagen

The nymphs of this genus have shallow mental clefts, and have
the margins of the pronotum prominently elevated, and the margins of

the lateral gills marked with black or dark spots.

The adults are characterized by cross-veins within the basilar

space and by pale stripes on all of the pleural sutures of the thorax.

Key to Species

MALES

a. Bases of hind wings tinted with carmine similar to that of the front

wings ; legs striped, buff and black or dark brown americana.

aa. Bases of hind wings tinted with brown ; legs entirely dark, not

striped titia.

FEMALES

a. Mesepisterna and mesepimera of the thorax without elongate spots of

green ; uniform bronze americana.

aa. Mesepisterna and mesepimera of the thorax with elongate spots of

green titia.

Hetaerina AMERICANA Fabricius

Nymph.—Color, brown or greenish.

Head pentagonal, about as long as broad
;
proximal segments of

the antennae nearly twice as long as all the remaining ones together

;

eyes black or dark; labium (Fig. 9) thickset, the cleft of the median

lobe hardly extending proximad of the articulations of the labial palpi

;

labial palpi with three end-hooks and five or six small setae at the



472

base of the distal segment; caudo-lateral margins of the head forming

a blunt tubercle.

Thorax twice as long as broad, a dark lateral line occurring in

some individuals, extending from the eyes to the bases of the second

pair of wing-cases, though, as a rule, this is much less distinct than

in Agrion; lateral margins of the pronotum distinctly elevated,

scalloped, and the margins produced at two points on each side to form
tubercles (Fig. 23) ; legs without heavy setae, usually light in color.

In younger and more plainly marked specimens the jjroximal half of

the femur is dark brown; this is followed b}' a liglit band, beyond
which the femur is again brown to the apex; tibiae with three faint,

dark rings, the bases and apices also dark ; tarsi light in color except

the apical half of the third segment and the tarsal claws, wliich are

usually black.

Abdomen : lateral keels feebly developed, not armed with setae

though ending abruptly on the apex of segment nine in a short blunt

tubercle ; ovipfisitor short and extending hardly caudad of the apex of

the ninth abdominal segment ; lateral gills three-sided, the median one

flat and considerably shorter than the lateral ones ; median gill dark
along the axis nearly to the apex and with three dark cross-bands;

axes of lateral gills sometimes dark, though more freciuently the whole
gill is light brown or buff and the three margins are.each marked with

three dark spots (Fig. 79).

Measurements

Length 23 mm.
Length of abdomen 12 mm.
Length of lateral gills 9-10 mm.
Length of metathoracic wing-eases .... 6 mm.
Length of median lobe 4 mm.
Width of median lobe 1.3-3 mm.

There seems to be a great deal of variation in the color markings
of tlie nymph, especially in the amount of dark pigmetit, and specimens

may be taken which are either practically without body markings of

any sort or are so dark and plainly marked as to make the collector

think he has taken another species.

Adult; Male.—Color, bronze and metallic green ; bases of the

wings carmine.

Head metallic bronze; median lobe of the labium subtriangular

in outline; labial palpi broad, the terminal segment black and as long

as the fixed hook of the first segment; front, vertex, clypeus, and



473

labrum, thinly pilose
;
postclypeus metallic green with a small buff spot

on the dorso-lateral margin, the anteclypeus with a triangular, median

light spot, the remainder dark ; labrum buff, but provided with a me-

dian, circular, black spot; exposed portions of the mandibles and their

trochantins buff; eyes uniform brown.

Thorax : prothorax bronze and black, thinly pilose ; caudal lobe

of the pronotum convex and projecting caudo-dorsad, the caudal

margin entire; proepimeron distinct; pleural sutures all marked with

buff-colored stripes, the interpleural suture distinct, cephalad of the

metathoracic spiracle ; metepimera largely buff but with a median longi-

tudinal stripe of bronze; intersternum with two dark spots on the

cephalic border which unite with a dark line covering the suture

caudad of it and between the epimera
;
paraptera subtriangular, black,

the caudal margins nearly straight ; legs striped, buff and black, the

coxae and trochanters buff with a few darker spots, the femora and

tibiae mostly dark with lighter stripes on the caudal surfaces, the front

femora with nine or ten setae in each row, and the tarsi and claws

black ; wings clear, the basal fourth, or more, bright carmine, anteno-

dals of the front wing nineteen or twenty, the stigma much longer

than the cell caudad of it (Fig. 78).

Abdomen metallic green or reddish brown, dull with age; seg-

ments three to seven with pale basal rings, interrupted on the dorso-

meson, the lateral surfaces of terga two to seven with a pale longi-

tudinal stripe from base to near apex ; first tergum with a pale lateral

apical spot; anal appendages (Figs. 34,38) with the superiors twice

as long as the inferiors, curved and somewhat expanded at the apex,

the lateral margins tuberculate, the mesal margins with two rounded

knobs.

Female.—Color, metallic green and in general lighter than that

of the male.

Head as in the male except that the antennae have the basal seg-

ment entirely pale ; postclypeus with a large transverse green spot, and

the lal)rum with a black mesal spot on the dorsal margin.

Thorax with the dorsal carina lined with buff, the pleural sutures

with much broader stripes than those of the male; wings (Fig. 74)
without carmine at the base, but slightly smoky on the basal third

and along the costal margin ; stigma white, and the antenodal cross-

veins about twenty-one in number.

Abdomen metallic green above, the lateral surfaces of the terga

with darker apical spots on segments one to nine, and terga two to

seven with narrow basal rings of paler color which are interrupted

on the dorso-meson; anal appendages of the usual type; ovipositor



474

(Fig. 112) with broad lateral valves, which are serrate on the ventral

margin and extend to the apex of segment ten
;
prostyles slender,

rc<d-like and bent ventrad at the apex (Fig. 41).

Measurements

Length, $ 44 mm.
Length, 2 42 mm.
Length of abdomen, S 36 mm.
Length of abdomen, $ 32 mm.
Length of hind wings, S 28 mm.
Length of hind wings, ? 29 mm.
Width of hind wings, $ 6 mm.
Width of hind wings, S 6 mm.

This species is common along tlie drainage ditcli nortji of Urbana.
Nymphs collected May 27 and 29, 191 5, emerged June 19. The species

flies until late in October and specimens have been taken as late as

October 22. It is apparently limited to the northern half of the state,

though probably occurring wherever conditions are favorable.

Specimens have been seen from Galena, Havana, Muncie, Oregon,
Peoria, Savanna, Urbana, and McHenry County.

HetaERINA TiTiA (Drury)

Nymph.—Unknown.
Adult; Male.—Color, very dark green and brown.

Head dark brown, faintly metallic; labium with subtriangular

median lobe, the palpi with broad black proximal segments, and black

distal segments about as long as the fixed hook of the proximal seg-

ment ; antennae brown ; clypeus and labrum shining ; front with a

broad transverse buff stripe immediately above the clypeus, the front,

vertex, clypeus, and labrum pilose, the setae brown.

Thorax black and brown, slightly bronzed
;
pronotum with the

caudal lobe somewhat pointed, convex, and projecting caudo-dorsad

;

proepimera distinct; interpleural suture distinct cephalad of the

spiracle; mesinfraepisternum buff, with a dorsal dark stripe; cephalic

shoulder of the mesepimeron light brown, the mesepisternum with a

greenish longitudinal stripe extending from the caudal margin nearly

to the spiracle; metepimeron with a median black stripe; intersternum

with two faint black spots near the cephalic margin; legs uniform

dark brown, the tibiae lighter in color than the femora, the setae of

the front femora in eleven or fourteen row'S, tarsi and claws black;



475

wings clear, the front wings carmine, and the hind wings brown at

base, the color, however, not occupying as much as one-fourth the

length of the wing; apices of the wings brown; stigma brown and

not longer than the cell caudad of it; front wings with about twenty-

four antenodal cross-veins.

Abdomen dark brown ; second tergum marked with a paler trans-

verse band beyond the middle, the lateral margins also pale; terga

three to six paler along the lateral margins, with narrow basal rings

interrupted on the dorso-meson ; segments seven to nine inclusive all

dull black, the sternum of the tenth buff; anal appendages (Fig. 119)
consisting of heavy black superiors, more than twice as long as the

inferiors, and having a few tubercles on the lateral surfaces of the

apical half, the niesal surfaces with basal knobs and thick subapical

projections; inferiors dark brown, reddish at base, short, and with

small apical points directed dorsad.

Female.—Color similar to that of the male.

Head similar to that of the male.

Thorax pale brownish, yellow, and green, the dorsal carina

black, the supraepi sterna of the mesothorax with a median elongate

spot extending cephalad from the wing bases half-way to the cephalic

margin, the cephalo-dorsal angles being also green; mesepimera with

elongate spots about the middle and nearer the ventral than the dorsal

margin; wings without carmine, the bases with only a slight tinge of

brown ; stigma nearly white, and surmounting one to one and a half

cells; antenodal cross-veins of the front wing twenty-one, postnodal

cross-veins twenty-six.

Abdomen similar in general color to that of the male, but the lateral

margins of terga eight to ten yellowish brown; dorsal carina of the

tenth tergum produced into a long blunt spine, beyond the apex of

the segment; ovipositor short, brownish yellow, the prostyles slender

and the caudal sternites of the eighth segment large and contiguous

on the meson as in amcricana, Figure 41.

Measurements

Length, S 51 mm.
Length, 9 44 mm.
Length of abdomen, 3 41 mm.
Length of abdomen, 9 34 mm.
Length of hind wings, $ 30 mm.
Length of hind wings, 9 29 mm.
Width of hind wings, $ 6-7 mm.
Width of hind wings, 9 6-7 mm.



476

There arc two representatives of this species in the collection of

the Illinois State Laboratory of- Natural History, both of which were
collected at Havana, Illinois. There are also three specimens in the

Bolter Collection of tlie University of Illinois, which are without

locality or date labels.

H. /n'co/or Burmeister is a synonym of //. titia (Williamson, '12).

Family COENAGRIONIDAB
The nymphs of this family possess flattened gills, the lateral ones

being flattened as well as the median. The median lobe of the labium
does not have a deep cleft, and the basal segment of the antenna is

small and does not exceed the second in length.

The adults are often brightly colored, frequently marked with

bright blue or green, but the wings are mostly clear and without smoki-
ness or tints of any kind. The antenodal cross-veins are few, never

more than two in number in Illinois species, and the postnodals are

also much reduced and fewer in number than in the Agrionidae. The
interpleural suture is never distinct as far cephalad as the metathoracic

spiracle.*

Key to Subfamilies

NYMPHS

a. Median lobe of labium spoon-like (Fig. 10) , the narrowed portion usu-

ally nuieh longer than the expanded poi'tion
;
gills (Figs. 48-52) more

or less spatulato, the margins nearly iiarallol and the tip.s lilunt

Lestixae.

aa. Median lobe of labium not spoon-like (Figs. 11-13), the narrowed
portion not much longer than the expanded portion

;
gills lanceolate,

acutel.v pointed at the tip, the margins not parallel.

.

Coexagrionin'ae.

ADULTS

a. M3 arising much nearer the arculus than the nodus (Fig. 85) ; front

without pale color immediately above the elypeus Lestinae.

aa. M., arising much nearer the nodus than the arculus (Pigs. 81-84,

87-90) ; front with a pale stripe immediatelj' above the elypeus

Coenagrioninae.

*The ns?o of the accessory genitalia in separating the males of closely allied

members of this family has failed to prove entirely satisfactory for such species as

Lestes forcipatua and dujanctus and the Enallagnia group composed of E. calvcrti.

raruncxdaiiim, civile, divagans, and doiibledayi. The structure of the penis in the

Enallagma group (Figs. 97,99,101,107,108) is so uniform that the advantage gained by
using the character is slight. It may be found that many of these species interbreed

—a condition already known to be true of carunculatum and civile—and it seems
almost certain that future investigators will unite L. forcipatns and disjunctus

when more complete biological data are in hand.



477

Subfamily LESTINAE

The nymphs of this subfamily are long, slender insects with very

slender legs. The median lobe of the labium is much contracted at

the base, the contracted portion being usually longer than the expanded
distal portion. The lateral keels of the abdomen are frequently pro-

duced at the apex into a short spinule, and the gills are long, spatulate,

and usually without heavy marginal setae and with more or less brown
pigment.

In the adults the nature of the wing venation is important. The
third median vein and the bridge unite with the R-M trunk nearer

the arculus than the nodus, and the stigma always surmounts two or

more cells. The long tibial and femoral setae, which are longer than

the distance between their bases, as well as the forcipate character of

the anal appendages of the male and the presence of a large ovipositor

with conspicuous sternites at the base of the cephalic pair of gon-
apophyses, are also important as diagnostic features.

As a rule the adults are dull in color as compared with the Coen-
agrioninae and match the color of their usual environment extremely

well.

Genus Lestes Leach

The subfamily Lestinae is represented in Illinois by a single genus,

Lestes. The nymphs of this genus are recognizable by the character

of the labium. The proximal segment of the labial palpus always has

two processes mesad of the distal palpal segment, one of them resem-

bling a fork with the median tines broken off, the remaining process

consisting of a long non-bifurcate projection with a short heavy hook
at the distal end and minute teeth along the mesal margins. (Fig. lo).

The adults are larger than most Coenagrioninae. Vein M2, of

both wings, always arises distad of the second postnodal cross-vein and
the stigma rarely surmounts more than three cells. The arculus is

one-third or one-fourth the length of the caudal side of the quadrangle.

The wings are commonly held horizontally when the insect is at rest.

Keys to Species

NYMPHS

a. Second segment of the labial palpus with thieo or four setae ; labium
broad at the proximal end, the contracted portion of the median lobe

hardl.y longer than the expanded portion and about one-third as

broad as the latter congener.

aa. Second segment of the labial palpus with only two setae or very
rarely three (uncatus) ; labium narrow at the proximal end, the con-



478

tractcd portion much longer than the cxi)anded portion and less than
one-third the width of the latter.

b. Gills pointed at tip (Figs. 51,52) ; venter of abdomen without a

median row of blaek spots.

c. Ovipositor of female not extending caudad of the eleventh seg-

ment; lateral gills not conspicuously contracted beyond the

middle unguiculatus.

cc. Ovipositor of female extending caudad of the eleventh segment;
lateral gills conspicuously contracted beyond the middle. . uncatus.

bb. Gills not sharply pointed (Pig. 49) ; venter of abdomen with or

without a median I'ow of black spots.

c. Lateral keels of segments 1-9 or 2-9 with long apical spines

;

venter of abdomen without a median row of black spots
;
gills not

conspicuously narrowed beyond the middle vigilax.

ec. Lateral keels of segments 3-9 or 4-9 with apical spines
;

gill.'?

(Eig. 49) conspicuously narrowed beyond the middle; venter of

abdomen with a median row of black spots ) forcipafus.

\ rectangularis.

ADULTS-

Females
a. Dorsum of thorax green.

b. Wings flavescent eurinus.

bb. Wings not flavescent.

e. Occiput and postgcnae pale inaequalis.

ce. Occiput and postgenae black.

d. Basal half of first abdominal segment yellow ; stigma always
surmounting less than three cells; length u.sually about
35 mm uncatus.

dd. Basal half of fir.st abdominal segment black; stigma iisually

surmounting three or more cells; length 43^7 mm. . . .vigilas.

aa. Dorsum of thorax black or dark brown, never green.

b. Metepimera with a black spot above and below the latero-ventral

carina congener.

bb. Metepimera without a black spot above and below the latero-

ventral carina.

c. Occiput and postgenae pale buff or yellow ; abdomen with a

greenish tint unguiculaius.

ce. Occiput and postgenae black or verj- dark brown ; abdomen never
with a greenish tint.

d. Tarsi black above
|
{^^'^,^'!'-_

dd. Tarsi with more or less pale yellow above rectangularis.



479

Males

a. Dorsum of the thorax and usually the abdomen metallic green.

b. Inferiors more than half the length of the superiors, but never
longer than the superiors.

c. Inferiors long and slender ; stigma usually surmounting three

cells vigilax.

CO. Inferiors broad and flat ; stigma usually surmounting less than
three cells uncatus.

bb. Inferiors either longer than superiors or less than half their length.

e. Inferiors less than half the length of the superiors ; wings flaves-

eent eurinus.

ec. Inferiors longer than superiors ; wings not flavescent . . inaequalis.

aa. Dorsum of the thorax and abdomen black or dark brown.

b. Inferiors shorter than half the length of the superiors ; metepimera
with black spots near the latero-ventral carina congener.

bb. Inferiors more than half the length of the superiors ; metepimera
without black spots near the latero-ventral carina,

c. Inferiors sigmoid, the apical two-thirds cui-ved in an opposite
direction to the superiors unguiculatus.

cc. Inferiors not sigmoid, the apical two-thirds not curved in an
opposite direction to the superiors.

d. Metapleural suture covered with a sooty black stripe

disjunctus.

dd. Metapleural suture not covered with a sooty black stripe,

e. Basal tooth of the mesal margin of the superior appendages
longer than the tooth of the distal third forcipatus.

ee. Basal tooth of the mesal margin of the superior appendages
shorter than the tooth of the distal third rectangularis.

Lestes congener Hagen

Nymph.—Color, -pale brown or greenish.

Head twice as broad as long, the caudo-lateral angles not project-

ing strongly and provided with few setae ; antennae long and slender

;

labium with the median lobe comparatively broad at the base, one-

third as broad as the expanded portion and about as long as the latter

;

mental setae six and sometimes a small seventh on each side, lateral

setae four or five, three or four of which are located on the distal seg-

ment ; inner, mesal lobe of the proximal segment of the palpus as

broad as the fork-like process between it and the distal segment of the

palpus ; labium, when folded, extending caudad between the metacoxae.



480

Thorax slender ; the distances between procoxa and mesocoxa,

and between mesocoxa and the nietacoxa nearly e(|ual; front femora
about half the length of the hind femora and all femora with faint

preapical rings of brown ; wing-cases short and extending hardly

caudad of the second abdominal segment.

Abdomen with poorly developed lateral keels wliich are provided

with apical spines on segments 5-9; gills (Fig. 50) broad, bluntly

pointed, and provided with three conspicuous cross-bands of dark pig-

ment, the length of the median gill about four times its greatest width;

ovipositor of the female reaching slightly beyond the apex of the tenth

segment.

Measurements

Length Ifi mm.
Length of abdomen 12 mm.
Length of gills 8 mm.
Width of gills 2 mm.
Length of metathoracic wing-eases. . . 5 mm.
Length of median lobe 3 mm.
Width of median lobe 1.5 mm.

Described from three nymphs received from Dr. E. M. Walker
and taken at Prince Edward Island, Canada, Aug. i, 191 5.

Adult; Male.—Color, dull brown and buff or yellow.

Head black, buff below ; median lobe of the laljium subquadrangu-

lar, the median cleft shallow, the labial palpi broad, the distal segments

much shorter than the fixed hook, and brownish at the tips ; antennae

uniform black, the first segment pale at the apex; postclypeus black

or dark brown, the anteclypeus, labrum, and genae to the level of the

fronto-clypeal suture yellow ; lateral ocelli with small yellow spots

laterad of them; front, remainder of the vertex, occiput, except occa-

sionally a transverse yellow stripe from the occipital foramen to the

compound eyes, black.

Thorax dark brown and yellowish buff, the prothorax dark brown,

the median lobes of the pronotum with pale lateral margins, and spots

on the meson near the caudal margin; caudal lobe of the pronotum
black

;
proepimeron black ; mesostigmal plates with pale lateral angles

;

dorsal carina usually with a pale line, the mesepisterna, except the

ventral half of the infraepisternum, black or dark brown; caudo-dorsal

angle of the metepisterna dark brown or black ; metepimera with an
elongate black spot near the ventro-lateral carina and a similar spot just

ventrad of the carina ; legs striped, the coxae buff, trochanters black

above, the femora black with a narrow pale stripe including the ceph-



481

alo-ventral row of setae, and a broad dorsal stripe, frequently divided

by a faint line or row of spots; tibiae yellow, with a dark stripe includ-

ing the cephalo-ventral setae ; tarsi and claws shining black ; wings

clear, with eleven postnodals in the front wing and nine or ten in the

hind ; stigma pale brown, surmounting about one and one-half to two
and one-half cells; Mo arising between the third and fourth postnodal

cross-veins in the front wing and between the second and third in the

hind wing
;
paraptera brown, caudal margins black.

Abdomen black and buff ; terga i-io with broad black longitudinal

stripes, the lateral margins with broad pale stripes, the pale color ex-

tending well to the dorso-meson in the form of basal rings on segments

three to seven inclusive ; first tergum with a black spot near the latero-

ventral margin, terga three to eight with narrow apical black rings

reaching their lateral margins ; anal appendages black (Figs. 123, 124)
and reddish, the superiors compressed, the ventro-mesal margins with

large subbasal teeth and a few setae beyond these to the apical third;

inferiors shorter than the superiors, usually less than half the length

of the latter and provided with a fine brush of silken hairs ; sterna 2-9,

inclusive, black, the tenth being pale and the first with a black median
spot.

Female.—Color similar to that of the male.

Head and thorax similar to those of the male.

Abdomen with interrupted basal rings on terga 3—6, inclusive,

the lateral stripes broader than those of the male ; sterna 2-7 black, one
with a black median spot and eight with a median black stripe ; anal
appendages of the usual type; superiors black; ovipositor with a black
line along the ventral margin, the margins serrate

; prostyles dark, long,

and nearly straight; ventral margins of the ninth tergum black imme-
diately dorsad of the ovipositor.

Measurements

Length, $ 34-35 mm.
Length, 9 32-36 mm.
Length of abdomen, $ 28 mm.
Length of abdomen, 2 24—29 mm.
Length of hind wings, S 19-20 mm.
Length of hind wings, 9 19-22 mm.
Width of hind wings, $ 4 mm.
Width of hind wings, 9 4 mm.

This species is distinguishable from disjuuctus, to which it seems
most closely related, by the metepimeral spots ; the males, by the short-

ness of the inferior appendages. The compound eyes are blue in life.



482

It appears on the wing late in summer and may be taken during

August and September.

Described from a large series of specimens in the collection of

E. B. Williamson. Probably occurs in Illinois.

Lestes disjunctus Selys

Nymph.—Not available for study.

Adult; Male.—Color, blackish brown and yellow.

Head blackish brown above, pale yellow below ; median lobe of

the labium pale, subquadrangular, the median cleft shallow, but with

the usual dark line extending to the base of the piece ; antennae black,

the two proximal segments very short, much shorter than the two distal

ones, the apex of segment two slightly paler; postclypeus almost black,

the anteclypeus, labrum, trochantins of the mandibles, and genae, yel-

lowish green ; occipital and postgenal regions black, becoming pollinose

with age ; eyes brownish.

Thorax: prothorax black, largely pollinose in older individuals;

proepimerp. and proepisterna distinct; caudal lobe of the pronotum
black, cephalic lobe black, median lobes black, the furrow separating

them indistinct; mesostigmal plates black; mesinfraepisterna black or

largely black, the supraepisterna blackish brown with the exception

of a narrow yellow stripe on the ventro-lateral margins ; mesepimera

dark brown with the exception of the cephalo-ventral shoulders, which

are yellow ; metepisterna largely yellow, becoming more or less black

with age from the spreading of the black stripe on the metapleural

suture; stripes of the metapleural sutures covering about two-thirds of

the metepimeron, the remainder of that sclerite yellow; postcoxal areas

buff, without black markings ; legs slender, pale, the coxae black and
pale yellow; femora striped, the hind femora with three black stripes,

the middle and front femora with two each ; tibiae with a single dark
stripe which diffuses over the segment on the distal third ; rows of setae

of the front femora composed of two and nine setae respectively;

wings clear, the antenodal cross-veins two, postnodals about eleven,

and M2 arising between the second and third postnodal cross-veins in

both wings ; stigma dark brown, surmounting two cells.

Abdomen brown to black, and yellow; first tergum black with the

exception of a very narrow apical ring ; dorsum of the second tergum
dark brown, the lateral margins marked by a narrow longitudinal yel-

low stripe, the dorsum of 3-6 dark brown, the stripe widened sub-

apically ; segment seven black, with a pale lateral stripe ; segments
eight, nine, and ten black; anal appendages (Fig. 133) blackish brown,



483

the superiors with tuberculate lateral surfaces, the mesal margins with

two nearly equal teeth; inferiors flat, placed horizontally, and slightly

swollen at the base and apex.

Female.—Color similar to that of the male.

Head similar to that of the male.

Thorax without the black stripe on the metapleural suture, and

the mesinfraepisternum largely pale.

Abdomen similar to that of the male except that the dorsal brown
stripes of the terga are more confined to the dorsal surface and the

lateral surfaces are mostly yellow or buff; ovipositor of the female

pale except the brown prostyles, extending caudad of the apex of seg-

ment ten ; anal appendages of the usual type ; dorsad of the superiors

and between them there is commonly an unpaired blunt process extend-

ing conspicuously beyond the apex of the tenth tergum.

Measurements

Length, $ 32-37 mm.
Length, S 35 mm.
Length of abdomen, S 25-30 mm.
Length of abdomen, 2 27 mm.
Length of hind wings, $ 17-20 mm.
Length of hind wings, 9 19 mm.
Width of hind wings, S 4^4.5 mm.
Width of hind wings, 9 4.5 mm.

There is great variation in the size of this species as well as in

its coloration. The black wash on the metapleural suture is a dis-

tinctive character of the older males, but the younger males and the

females are not easily separated from forcipatus and it is possible that

this species is a synonym of the latter. The nymphs are also reported

to be nearly identical with forcipatus.

Not common in Illinois though occurring in certain localities prob-

ably with forcipatus and rectangularis.

Lestes eurinus Say

Nymph.—Not available for study.

Adult; Male.—Color, metallic green and yellowish buff.

Head metallic green; mouth-parts buff, the median lobes of the

labium subquadrangular, with a shallow cleft and a dark line extend-

ing proximad to the base; distal segment of the labial palpus dark

brown, shorter than the fixed hook ; antennae uniform dark brown, the



484

sltndcr terminal segments long, aristiform; postclypcus black, antc-

clypeus, exposed portions of the mandibles, and genae brown or green-

ish yellow, the front, vertex, and all of the occiput and postgenae,

metallic green ; eyes dark brown.

Thorax metallic green and buff; pronotum metallic green, some-

times pollinose, the caudal and cephalic lobes becoming black with age

;

proepimeron and proepisternum distinct, black and green; mesostigmal

plates black; dorsal carina brown, the mesosupraepisterna metallic

green; mesopleural suture brownish, the dorsal half of the mesinfra-

episterna, black ; mesepimera black or green, the dark color sometimes
extending ventrad onto the metepisterna or epimera ; remainder of the

metapleura and the intersternum yellow, jjollinose with age ; legs

striped, dark brown and buff ; coxae buff and dark brown ; middle and
hind femora with two broad, dorsal, brown or black stripes and a

narrow, dorsal, pale one, the apices of the femora dark; front femora
without the dorsal, pale, longitudinal line, the entire dorsum being dark

brown; tibiae with broad, ventral, brown stripes including the setal

rows, the tips dark ; tarsi dark brown, the claws deeply notched at the

apex, the two teeth nearly equal in length ; wings usually flavescent and

with fourteen or fifteen postnodal cross-veins in the front wing and

twelve to fifteen in the hind; Mo arising between the third and fourth

postnodals in the front wing and between the second and third in the

hind ; stigma long and narrow, surmounting two and one-half to three

and one-half cells in both wings.

Abdomen metallic green and black and buff; dorsum of terga i-8

inclusive, green, the lateral margins of the same terga buff, the bufif

stripe becoming dark brown or black on the apices of 4-8; venter of

3-8, and all of segments nine and ten and sometimes seven and eight

black, the terminal segments pollirjose with age ; anal appendages black,

the superiors long and curved, the dorso-lateral margins coarsely tuber-

culate at the apices, the meso-ventral margins with a single sharp basal

tooth, and a median projection which has several smaller teeth at the

apex; inferiors blunt at the apices and each with a brush of fine setae.

Female.—Color, metallic green, and yellow and black.

Head similar to that of the male.

Thorax : prothorax similar to that of the male ; mesothorax with a

very broad brownish stripe covering the dorsal carina and a green

longitudinal stripe in the middle of each mesosupraepisternum ; meso-
pleural suture with a broad brownish stripe which extends across the

dorsal portion of the infraepisternum ; metepimera with indefinite,

brown, oblique stripes.



485

Abdomen similar in general color to that of the male ; anal appen-

dages largely black or dark brown, the process immediately above and

between the superiors projecting as in disjimctus; ovipositor with

broad lateral valves, the ventral margins coarsely toothed, the distal

portion separated from the tenth segment by a considerable interval

;

more than the ventral half of the lateral valves black; eighth sternites

large, conspicuous, nearly black, and contiguous on the meson.

Measurements

Length, $ 48-49 mm.
Length, 2 47 mm.
Length of abdomen, $ 39 mm.
Length of abdomen, S 36 mm.
Length of hind wings, $ 29 mm.
Length of hind wings, 9 28 mm.
Width of hind wings, S 6.-5 mm.
Width of hind wings, 9 5.5 mm.

Described from two males in the Bolter collection of the Uni-

versity of Illinois and a number of females in the collection of E. B.

Williamson.

The species is closely related to vigilax and inacqiialis, but both

sexes may be distinguished by the flavescent wings ; the males, by the

short inferior anal appendages.

Probably occurs in Illinois.

Lestes eorcipatus Rambur

Nymph.—Color, buff or green.

Head brown and buff; labium, when folded, extending just caudad
of the mesocoxae; mental setae six, the lateral setae three, two of

which are located on the distal segment of the palpus; antennae of the

usual Lestes type.

Thorax about as long as broad, brown ; legs slender, the femora
all with faint subapical rings and several rows of small setae; tibiae

with dark brown apices and with a few three-pointed subapical scales

;

tarsi with the apical half of the last segment and the tarsal claws dark
brown; metathoracic wing-cases extending to the middle of the third

abdominal segment.

Abdomen long and slender ; lateral keels with heavy setae at the

apices on segments five to nine, and a single row of smaller ones from
the bases to the apices of the keels of the same segments; terga all with



486

much more pigment than the sterna, and with small setae distributed

evenly over the surfaces; sternum of segment ten with long hair-like

setae; gills (Fig. 49) spatulate, broadest just proximad of the middle,

three or four times as long as broad; tips rounded or obtusely pointed,

black, and two rather indistinct dark cross-bands proximad of the tip

;

gills sometimes nearly black.

Measurements

Length 19-20 mm.
Length of abdomen 14 mm.
Length of gills 8.5-9 mm.
Width of gills 2-3 mm.
Length of median lobe 2.4 mm.
Width of median lobe .5-1.7 mm.

Adult; Male.—Color, dark brown and yellow.

Head brown and buff, the median lobe of the labium pale or

nearly white, subquadrangular in outline, the median cleft shallow

and narrow but apparently extending well towards the base of the

piece; proximal segment of the palpus pale, except the distal half of the

fixed hook which is black ; antennae dark brown with a short basal

segment, a much longer second segment, and two terminal aristiform

segments which together are much longer than the two basal ones;

clypeus and labrum pale yellow or greenish; exposed portions of the

mandibles, their trochantins, and the genae as far dorsad as the fronto-

clypeal suture, pale ; front and vertex brown ; occipital and postgenal

regions largely dark brown or black, becoming pollinose with age.

Thorax brown and yellow
;
prothorax brown above, pale below,

the proepimera distinct, pale, with a dark dorsal border; caudal lobe

of the notum not especially prominent or convex, the cephalic lobe

with a median circular black spot and the median lobes each with an

irregular H-shaped dark mark ; cephalic portion of the prescutum tri-

angular, not deeply depressed; stigmal plates brown and black; pleural

sutures and the dorsal carina pale, the pale stripe of the mesopleural

suture becoming bluish with age ; legs striped, yellow and black, the

coxae and trochanters entirely pale, the femora and tibiae striped and
the tarsi and claws entirely black; wings with ten to eleven postnodal

cross-veins and with Mj arising between the third and fourth post-

nodals in the front wing and between the second and third in the hind

wing.

Abdomen dark brown, often with a trace of metallic green;

sterna of segments three to nine black; dorsum of terga i-io with



487

brown longitudinal bands which are considerably narrowed basally on

segments three to seven and conspicuously widened subapically on seg-

ments 2-6, the apically widened portion enclosing a lateral yellow spot

en segments 3-6 ; segment nine completely black except a small lateral

yellow spot ; lateral surfaces of terga 1-8 and ten, yellow; anal appen-

dages (Fig. 137) consisting of broad superiors which are coarsely

tuberculate on the lateral surfaces and have two strong, mesal teeth

;

inferiors nearly as long as the superiors, not laterally compressed, but

flattened and placed horizontally.

Female.—Color similar to that of the male.

Head and thorax not appreciably different from those of the male.

Abdomen without the yellow lateral spots of the male ; ovipositor

extending caudad of the tenth segment, the lateral valves serrate on

the apical two-thirds of the ventral margins (Fig. 114).

Measurements

Length, S 44 mm.
Length, 9 41 mm.
Length of abdomen, .S 30 mm.
Length of abdomen, 2 32 mm.
Length of hind Avings, $ 23-24 mm.
Length of hind wings, 9 24 mm.
Width of hind wings, $ 5 mm.
Width of hind wings, 9 5 mm.

One of the commonest of the Lestinae in Illinois. The nymphs
usually occur along with rectangularis in shady stagnant pools. The
species is on the wing from early June well into September, and nymphs
have been taken at Urbana late in July and at Lexington, Ky., late in

August. It seems probable that there is more than one brood of the

species per year.

The nymph is inseparable from rectangularis and there seems to

be no noticeable difference in the length of the developing ovipositor

of the female as Walker inferred there might be ('14: 197).
The adult females are also inseparable from rectangularis except

by the comparatively shorter length and the black tarsal segments. As
already mentioned, the females have no important characters which

differentiate them from the species disjunctus.

Lestes inaequaeis Walsh

Nymph.—Unknown.
Adult; Male.—Color, metallic green and black; or bronze and

black above, yellow or buff below.



488

Head green and yellow ; labium buff, subquadrangular, the shal-

low cleft apparently extending to the base of the piece; palpi broad;

antennae dull brown, the first segment much shorter than the second

and with a pale ring at the distal end
;
postclypeus metallic green or

black, the anteclypeus and labrum, except a small short black stripe

on the lateral margins, pale yellowish green ; exposed portions of the

mandibles, the genae as far dorsad as the fronto-clypeal suture, yel-

low, the remainder of the front and the vertex, metallic green ; occiput

and postgenae largely yellow ; compound eyes brown.

Thorax metallic green above, yellow or buff below, the pronotum
usually black, including the cephalic, median, and caudal lobes, the

proepimera black on the dorsal half, the ventral half buff; mesosupra-

episterna metallic green, the infraepisterna black on the dorsal half, the

remainder yellow ; mesepimera metallic green except the cephalo-ven-

tral shoulder, which is yellow ; tlorso-caudal angles of the metepimera

with a triangle of green, remainder of the metapleura and the inter-

sternum pale yellow ; legs striped, black and yellow ; coxae entirely buft,

trochanters, at least the middle and hind ones, with a black dorsal

stripe ; middle and hind femora with three black stripes, a ventral and
two dorsal, and three yellow stripes, the front femora, however, with

two black stripes, the cephalic one including the cephalo-ventral row of

setae ; tibiae with a single ventral black stripe including the cephalo-

ventral row of setae ; tarsi black, the claws long, black, and deeply bifid

at the tip ; wings clear, with sixteen postnodal cross-veins in the front

wing and thirteen to fourteen in the hind ; Mo arising between the

fourth and fifth postnodals in the front wing and between the third

and fourth in the hind ; stigma surmounting from slightly less than

two to two and one-half cells.

Abdomen with the dorsum of terga i-io dark, the basal segments

metallic green, the apical segments dull black ; lateral margins of terga

1-8 pale yellow or buff, the color extending well towards the meson on

the base of segments 3-6; sterna one and ten yellow, 3-9 inclusive,

black, shining ; anal appendages long, black, the superiors pale at the

base, the meso-ventral margins with a large basal tooth (Figs. 131,

132) and a number of smaller ones distad of this; dorso-lateral sur-

faces of the appendages coarsely tuberculate; inferiors longer than the

superiors, the tips bent mesad, approximate and finely pilose ; parameres

of the eighth sternum small, subquadrangular; bases of the inferiors

large and apparently fused.

Female.—Color similar to that of the male.

Head similar to that of the male.



489

Thorax similar to that of the male excepting that the dorsal carina

and mesopleural suture show distinct brown; legs with one dorsal

black stripe, frequently reduced to a row of spots; wings with the

stigma surmounting slightly less than three cells.

Abdomen with lateral, marginal, pale stripes on all terga, the

stripes as a rule broader than those of the male; anal appendages of

the usual type, the superiors pale, slightly darker at the tips; ovipositor

long, the lateral valves widely separated from the tenth segment at the

apex, the ventral half, or more, black; prostyles slender, bent ventrad

at the tips, and with a black dorsal stripe ; sternites of the eighth seg-

ment large, the caudo-dorsal angles acute.

Meaxurcments

Length, 5 54 mm.
Length, 9 49 mm.
Length of abdomen, $ 43 mm.
Length of abdomen, 5 38.5 mm.
Length of hind wings. S 29 mm.
Length of hind wings, 9 28 mm.
Width of hind wings, S 6.5 mm.
Width of hind wings, 9 5.5 mm.

Described from two males and two females in the collection of

Mr. E. B. Williamson.

Not taken in Illinois by the writer, but reported by Walsh ('62)

from the vicinity of Rock Island. The species is closely related to

vigilax, but is distinguishable from the latter by the pale occiput and

the long inferior anal appendages of the male.

LESTES RECTANGUtARis Say

Nymph.—Color, bufif or pale green.

Head elliptical, the width much greater than the length ; eyes dark

;

caudo-lateral margins of the head without setae ; labium extending

caudad between the metacoxae ; mental setae six ; lateral setae three,

two being on the distal segment of the palpus.

Thorax : mesothorax and metathorax much wider than the pro-

thorax ; legs slender, the femora with longitudinal rows of minute

setae, the apices of all the femora fuscous and with a subapical dark

ring ; tibiae with small setae arranged in rows and with fuscous apices

;

tarsi with the apical half of the third segment and the claws dark

brown, the hind tarsi with a very long apical segment and a very short

proximal one.



490

Abdomen : cuticle provided with minute setae and somewhat
heavily pigmented with brown ; lateral keels with heavy apical setae on
segments 5-9 and with about nine smaller setae along the keels to their

bases; sterna with a double row of median spots, two to each segment;
segment ten hairy beneath; gills similar to those of forcipatus, with

a row of short setae on both margins, the extreme tips being usually

free; the portions of the eleventh segment proximad of the lateral gills

bear five or six small setae on the ventral surface ; the pigmentation

of the gills is usually brownish, though frequently black, but the gill

is not as a rule as black as the gill of forcipatus; female ovipositor ex-

tending to the apex of the tenth abdominal segment.

Measurements

Length 22 mm.
Length of abdomen 17 mm.
Length of gills 9.5 mm.
"Width of gills 2.3 mm.
Length of median lobe 4 mm.
Width of median lobe 5-2.0 mm.

Adult; Male.—Color, dark brown to black, and sulphur-yellow.

Head brown and yellow ; labium pale, the median lobe subquad-

rangular, with a shallow cleft and darker stripe extending proximad
to the base; palpi rather short; antennae entirely brown, the first seg-

ment much shorter than the second, and the third and fourth much
longer than the first two together; postclypeus dark brown, shining,

the anteclypeus, labrum, exposed portions of the mandibles, their

trochantins, and the genae, shining yellow ; front and vertex, dull

brown, nearly black, the preocellar furrow very deep and extending

laterad nearly to the bases of the antennae ; occiput and postgenae black,

pollinose with age.

Thorax brown and yellowish; pronotum yellowish buff, the ce-

phalic lobe with a large median brown spot, the median lobes each with

an irregular H-shaped mark which covers a large portion of the lobe

in the older specimens ; caudal lobe blackish brown, the caudo-lateral

margins pale; supraepisterna of the mesothorax with a broad, brown,

longitudinal stripe from cephalic to caudal margins, covering about

three-fourths of the sclerites, the lateral margins of the stripe irregular;

mesopleural suture covered by a broad yellow stripe which is widest

cephalad, narrowed near the wing bases, and becomes bluish with age

;

mesepimera with longitudinal median brown stripes extending from
near the caudal margin to the cephalic shoulder, widened considerably



491

caudad and in contact with the mesopleural suture adjacent to the wing

bases, narrowed cephalad, and coming to a rather abrupt end on the

cephaHc shoulder; margins of the stripe irregular; metepisterna pale

yellow with a triangular brown spot on the caudo-dorsal angle; re-

mainder of the pleura and the intersternum pale yellow or buff; legs

buff and black or dark brown, the coxae and trochanters pale, the

femora with two brown stripes each, a cephalo-dorsal one and a ventral

one between the rows of setae ; tibiae with a single, cephalo-ventral

brown stripe including the cephalic row of setae ; tarsi and claws brown,

the dorsum of the tarsal segments usually more or less yellow; wings

with eleven to twelve postnodal cross-veins. Mo arising between the

third and fourth postnodals in the front wing and between the second

and third in the hind wing ; stigma surmounting slightly more than two
cells in both wings.

Abdomen brown and yellowish, long and slender; terga one and
two brown on the dorsum, pale on the sides, the stripe on two con-

tracted near the middle ; terga 3-7 with yellow lateral margins, nar-

row interrupted basal rings and longitudinal brown stripes on terga

eight and ten, and a triangular, lateral, apical, spot on nine ; anal ap-

pendages (Fig. 128) brown or blackish, the superiors mostly smooth
and not coarsely tuberculate on the lateral surfaces, the basal, mesal

tooth small, and much smaller than the tooth at the distal third of each

superior; inferiors more than half the length of the superiors, black,

the tips laterally compressed.

Female.—Color the same as that of the male.

Head and thorax not appreciably different from those of the male,

with the exception of the slightly wider pale stripes on the mesopleural

suture.

Abdomen shorter than that of the male ; anal appendages of the

usual type (Fig. 115); ovipositor extending as far caudad as the apices

of the anal appendages or beyond, the lateral valves broad, and with

serrated ventral margins, the ventral half being usually black.

Measurements

Length, S 50-52 mm.
Length, 9 46.5 mm.
Length of abdomen, S 33^2 mm.
Length of abdomen, 9 31-34.5 mm.
Length of hind wings, 3 18.5-24 mm.
Length of hind wings, 9 20-23 mm.
Width of hind wings, S 5 mm.
Width of hind wings, 9 5 mm.



492

This species occurs in the same localities in which fordpatns is

found. Nymphs taken at Urbana emerged as early as May 29 and as

late as Julv 17, tiie species having a considerable range in the period

of emergence. There is a possibility that this species has a two-

brooded life cycle.

Specimens have been seen from Urbana, Galena, Lake Villa, Ore-

gon, Savanna, and McHenry County.

Lestes uncatus Kirby

Nymph.—Color, bufif or green.

Head broad, the caudo-lateral margins not projecting and with-

out heavy setae; antennae of the usual Lestes type; mental setae six

or seven on each side ; lateral seta three, two of which are located on

the distal segment ; marginal setae of the mentum extending to the base

of the expanded portion of the median lobe ; labium, when folded, ex-

tending caudad of the metacoxae.

Thorax : legs very long and slender, the apices of the femora

and the apices of the tibiae and the distal half of the third tarsal seg-

ments brown; wing-cases extending to the middle of the fourth ab-

dominal segment.

Abdomen with well-developed lateral keels which are provided

with short spines on the apices of segments 5-g; cuticle uniform in

color, the dorsum of segments nine and ten and the venter of segment

ten with long, fine, silken hairs; ovipositor of the female long and ex-

tending Iieyond the apex of the eleventh segment
;
gills conspicuously

contracted beyond the middle as in rcctangularis and forcipatits, rather

sharply pointed at the apex, the point similar to that of niiguiculatiis.

Measurements

Length 18 mm.
Length of abdomen 11 mm.
Length of gills 8 mm.
Width of gills 2 mm.
Length of median lobe 5.5 mm.
•Width of median lobe ..3-1.6 mm.

Described from a single specimen collected by Dr. Edna Mosher

in July, 1915, at Orono, Maine.

Adult; Male.—Color, metallic green and pale yellow.

Head dark green above, pale below ; occiput black, the median

lobe of the labium pale and subquadrangular with a typical cleft;



493

palpiger short and indistinct; fixed hook of the proximal segment

longer than the distal segment, black at the tip; antennae black, the

second segment pale at the distal end; postclypeus black; the ante-

clypeus, labrum, exposed portions of the mandibles, their trochantins

and the genae, pale yellow ; front, vertex, clypeus, and labrum thinly

pilose, the setae pale ; eyes pale yellow.

Thorax metallic green, black, and yellow
;
pronotum green, the

caudal lobe narrow, the median lobes not distinctly separated, pro-

epimeron and proepisternum black, pollinose with age, the suture be-

tween the epimeron and notum indistinct; dorsal carina of the meso-
thorax black; mesosupraepisternum green, the mesinfraepisternum and
the mesopleural suture black ; mesepisternum green with the exception

of the cephalo-ventral shoulders ; metapleural suture usually black, the

stripe indefinite, increasing in extent with age and covering a large por-

tion of the metepimera ; postcoxal areas buff ; legs black and buff, the

coxae pale and black, femora with three black stripes alternating with

three bufif-colored ones ; tibiae, tarsi and claws black ; setal rows of

the front femora composed of two and nine setae respectively; wings
clear, the antenodal cross-veins two in number, postnodal cross-veins

ten to eleven ; stigma of the front wing surmounting two cells ; stigma

of the hind wing slightly smaller than that of the front wing; Mg
originating between the third and fourth postnodal cross-veins in the

front wing and between the second and third in the hind wing.

Abdomen metallic green; first tergum green on the dorsum and
with a small, black, lateral basal spot on each side; dorsum of the sec-

ond tergum green, the green extending well onto the sides, the latero-

ventral margins, however, being pale; terga 3-7 with broad, longitu-

dinal green stripes, widened subapically, and with narrow basal, dor-

sally interrupted, yellow rings and longitudinal lateral stripes; all of

segments eight, nine, and ten green above, black or pollinose below;
sternum of segment one with a median black spot at the caudal end,

3-10 black; superior anal appendages (Figs. 135, 136) black at the tip,

brownish at the base, the lateral surfaces tuberculate, the mesal mar-
gins with a large basal tooth and a row of small ones beyond to the

distal third ; inferiors broad, black and distinctly expanded at the apex.
Female.—Color, metallic green and yellow.

Head similar to that of the male.

Thorax with pale dorsal carina and mesopleural sutures, and
usually lacking the black stripe on the metapleural suture.

Abdomen : proximal half of the first tergum with a pale dorsum

;

terga 8-10 with broad lateral stripes of yellow; first sternum without
the black spot and the eighth, instead of being all black, has a mesa!



494

stripe ; superior anal appendages black at the tips, slightly longer than

the inferiors; ovipositor with the lateral valves black on the ventral

half, the apex extending well caudad of the tenth segment; prostyles

black at the tip and on the dorsal surfaces, the tips extending beyond

the apices of the anal appendages.

Measurements

Length, S 34 mm.
Length, 9 39 mm.
Length of abdomen, $ 26-28 mm.
Length of abdomen, 2 29 mm.
Length of hind wings, S 21 mm.
Length of hind wings, 9 23 mm.
"Width of hind wings, 3 4.5 mm.
Width of hind wings, 9 4.5 mm.

A moderately common species though not as common as either

rccfangtdaris or forcipatus. Taken at Oregon July i, 191 5, at Free-

port July 8, and at Urbana.

Lestes unguiculatus Hagen

Nymph.—Color, light brown or green.

Head about twice as broad as long, subelliptical, the caudo-lateral

angles not projecting, and provided with a few weak setae; antennae

slender, entirely pale, the third segment longest, segment two longer

than one; labium slender, and extending caudad of the mesocoxae;

mental setae seven, lateral setae three, two of which are located on the

distal segment of the palpus; lateral marginal setae of the mentum
about twelve, the row extending from the articulation of the palpus to

the base of the expanded portion.

Thorax slender, much contracted behind the head, about as broad

as long; legs slender, the femora with rows of short setae and faint

preapical rings of brown ; tibiae with rows of setae, the apices brown

;

tarsi pale except the apical half of the third segment which is brown;

metathoracic wing-cases extending caudad to the middle of the third

abdominal segment.

Abdomen long and slender, the lateral keels moderately well de-

veloped and possessing spines at the apices of segments 5-9; venter

of the abdomen usually much paler than the dorsum though sometimes

with faint median stripe and stripes just ventrad of the lateral keels;

caudo-lateral angles of terga 1-8 sometimes with darker spots; gills



495

widest near the base, and gradually tapering to a point at the apex, not

conspicuously contracted beyond the middle (Figs. 51, 52).

Measurevients

Length 19 mm.
Length of abdomen 14 mm.
Length of gills 9 mm.
Width of gills 1.5 mm.
Length of median lobe 2 mm.
Width of median lobe 5-1.5 mm.

Adult; Male.—Color, dull brown or metallic green and yellow.

Head metallic green and brown, often more or less bronze; me-

dian lobe of the labium subquadrangular, with the usual cleft; prox-

imal segment of the antennae with pale spot at the distal end, the re-

maining segments dark
;
postclypeus dull metallic brown, the anteclyp-

eus, labrum, and the exposed portions of the mandibles, their

trochantins, and the genae, shining yellow ; eyes slate-gray ; occipital

and postgenal regions wholly yellow.

Thorax dull brown and yellow ; caudal margin of the pronotum
entire, the caudal lobe narrow and not convex; cephalic lobe much
longer and possessing a median, circular, black spot ; median lobes with

irregular H-shaped black or dark marks, one to each lobe
;
proepimeron

distinct, pale brown, black on the dorsal margin; mesosupraepisterna

dull metallic brown, sometimes greenish, with the lateral fourth yellow

;

mesopleural suture with a broad yellow stripe ; mesepimeron almost

entirely brown, with the exception of the cephalic shoulder; mesinfra-

episternum with the dorsal half brown or greenish in older specimens

and with a median spot in younger individuals, the remainder of the

sclerite pale ; metepisterna with triangular brown spots adjacent to the

wing bases; metapleural suture and the metepimera pale buff; post-

coxal areas pale yellow, without dark spots ; paraptera crescentic, the

caudal margins faintly emarginate; legs striped, the coxae and the

trochanters buff, the femora pale yellow with two black or dark brown
stripes ; tibiae with a single brown stripe including one of the two rows
of setae; tarsi and claws black; front femoral rows of setae containing

three and eight setae respectively ; wings clear, the postnodal cross-veins

about eleven, and Mo originating between the second and third in the

front wing and between the first and second, usually near the second,

in the hind wing.

Abdomen mostly 3'ellow in recently emerged specimens, dark me-
tallic green or brown in older ones; dorsum of the first tergum brown



496

on the caudal half; terga 2-10 all with brown, dorsal, longitudinal

bands, extending from the cephalic nearly to the caudal margins, the

bands i)eing slightly enlarged at tlie caudal ends; terga 2-in with nar-

row rings of brown on the caudal margins; sterna 3-8 black ; nine and

ten, pale; anal appendages (Figs. 125, 126) consisting of strong su-

periors, coarsely tuberculate on the lateral surfaces rmd hairy at the

ai)ices, the mesal margins possessing a large basal tooth and a number
of smaller ones beyond this to about the distal third; inferior appen-

dages sigmoid, the distal two-thirds curved in an opposite direction to

the superiors.

Female.—Color similar to that of the male.

Head and thorax identical with those of the male.

Abdomen similar to that of the male with the exception of the

dorsa of the cephalic terga, which are as a rule paler in color, and

terga nine and ten, which possess a mesal dark line; ovipositor reach-

ing apex of tenth segment, the lateral valves black below, the ventral

margins serrate or coarsely toothed.

Measurements

Length, $ 39 mm.
Length, 9 35 mm.
Length of abdomen, $ 27. mm.
Length of abdomen, 9 27 mm.
Length of hind wings, $ 21 mm.
Length of hind wings, 9 22 mm.
Width of hind wings, $ 5 mm.
Width of hind wings, 9 5 mm.

A very common species at Urbana, occurring in abundance in

pools north of town. The nymph is easily separated from rcctangu-

laris and forcipatus by means of the shape of the gills. The adult is

also easily separated from rectangularis and forcipatus and seems to

be most closely related to uncatns, from which species it differs mainly

in color though also in the shape of the anal appendages of the male and
the length of the ovipositor of the female. The nymph is more closely

related to uncatiis than to any other species.

The species has a wide distribution in Illinois and flies from early

June to August.

Lestes vigilax Hagen

Nymph.—Color, light brown or green.

Head broad, about twice as broad as long, the caudo-lateral angle

not projecting and without setae; antennae slender and of the usual



497

Lestes tj-pe; labium very slender and when folded extending caudad

about to the metacoxae ; mental setae five or six ; lateral setae three,

two of which are located on the distal segment of the palpus ; marginal

mental spinules apparently wanting or few in numlDer and not extend-

ing proximad to the base of the expanded portion ; the teeth of the

mesal margins of the mesal lobe of the proximal segment of the palpi

are large and square and the furrow representing the median cleft of

the median lobe is conspicuous and extends proximad one-third the

length of the expanded portion.

Thorax slender; legs very slender, the femora and tibiae with

rows of short setae ; femora with subapical rings of brown, the tips

of the tibiae and the distal half of the third tarsal segment also dark
brown ; wing-cases extending about to the middle of the third abdom-
inal segment ; lateral keels with strong apical spines on segments 1-9
inclusive, the seta at the apex of nine especially long; gills (Fig. 48)
very long and slender and of about equal width throughout, the apices

bluntly pointed ; ovipositor of the female nearly reaching the ape.x of

segment ten.

Measurements

Length 21-30 mm.
Length of abdomen 17-22 mm.
Length of gills 13 mm.
Width of gills 1.25-1.75 mm.
Length of median lobe 3.3—

l

nnn.

Width of median lobe 1.5-2 mm.

The nymph is the longest of any species of Lestes. It is easily

recognizable by the slender gills (Fig. 48)- and the apical setae of the

lateral keels.

Described from a single exuvium obtained from Dr. E. M.
Walker and several specimens in the collection of the Illinois State

Laboratory of Natural History from Grass Lake and Havana, 111.

;

dates of collection of the specimens from Grass Lake June 23, 24, 1892.

Adult; Male.—Color, dull metallic green and buff.

Head dull greenish black or black ; median loI)e of the labium sub-

quadrangular, the median cleft shallow; fixed hook of the palpus black

at the apex ; antennae black, the tip of the first segment slightly pale,

the second segment twice as long as the first ; postclypeus black, the

anteclypeus brown ; labrum pale green ; exposed portions of the mandi-
bles, their trochantins, and the genae, pale brown ; front and vertex

metallic green.



498

Thorax metallic green, prothorax largely black, becoming polli-

nose with age; suture between pronotum and the proepimeron indis-

tinct; caudal lobe of the notum much narrower than the cephalic lobe

and considerably widened on the meson ; furrow separating the median

lobes obscure ; cephalic portion of the prescutum small, triangular, and

little depressed ; mesosupraepisterna and mesepimera green, the meso-

pleural suture and the dorsal carina with pale lines which become dark

with age; mesinfraepisternum black, the metapimera, metepisterna

and intersternum pale at first but black or pollinose with age ; legs buff

and black; coxae pale and black, femora almost entirely black, with

a narrow pale stripe between the setal rows on the ventral surface, and

a short stripe on the dorsal surface of the hind femora; rows of front

femoral setae Consisting of two and eight setae respectively; tibiae and

tarsi black ; wings clear, the antenodal cross-veins two, postnodals fif-

teen to seventeen in the front wings and twelve to thirteen in the hind

wings; Mo arising between the fourth and fifth postnodal cross-veins in

the front wings and between the third and fourth in the hind wings;

stigma usually surmounting three cells, light brown or nearly white in

color.

Abdomen metallic green and black ; terga i-6 with narrow lateral

stripes, 7—10 black; sterna of all segments black, the first sometimes

light, but black in older specimens ; superior anal appendages black, the

lateral surfaces tuberculate and the mesal margins with a basal hook
and two indentations between this and the apical third ; inferiors long

and slender, not dilated at the apex (Figs. 129, 130).
Female.—Color, metallic green and black.

Head and thorax similar to those of the male.

Abdomen long and very slender, the dorsum of terga i-io and
apical rings on all terga except the two caudal ones dull brown or

greenish; sterna 2-8 mostly black, ovipositor long and slender, the

prostyles long and the eighth sternites at the base of the cephalic pair

of gonapophyses with a long dorso-caudal projection.

Measurements

Length, S 43-47 mm.
Length, 9 43-45 mm.
Length of abdomen, S 34-38 mm.
Length of abdomen, 9 34—36 mm.
Length of hind wings, $ 21-25 mm.
Length of hind wings, 9 26-27 mm.
Width of hind wings, $ 5 mm.
Width of hind wings, 9 6 mm.



499

Males possessed by the Illinois State Laboratory of Natural His-

tory were collected at Cedar Lake, 111.,—Lake Villa—August 3, 1887.

The female was described from material obtained from Mr. E. B.

Williamson.

The species has not been seen as far south as LTrbana.

Subfamily COENAGRIONINAE
The nymphs have short labia, gradually contracted proximad and

not at all spoon-like. The gills are more or less lanceolate, acutely

pointed at the tip, and the smaller tracheae are commonly well devel-

oped, pigmented, and visible to the naked eye. The abdomen is short

in proportion to its diameter.

The adults are distinguished from the Lestinae by means of the

wing venation, M3 arising nearer the nodus than the arculus. The
femoral and tibial setae are much shorter than those of the Lestinae

and the coloration of the body is frequently bright, the yellows, blues,

and reds being often conspicuous. The anal appendages of the male

are short and the eighth sternites at the base of the cephalic pair of

gonapophyses of the female are reduced to small triangles or are want-

ing.

Key to Genera

NYMPHS

a. Gills half as broad as long (Figs. 58, 63, 67, 68) ; labium without

mental setae
;
proximal segment of the labial palpus with two similar

fixed hooks Argia.

aa. Gills not more than one-third as broad as long ; labium provided

with mental setae; proximal segment of the palpus with a single,

sharp, fixed hook, and a tn;ncate process with teeth at the apex.

b. Caudo-lateral angles of the head projecting and forming a blunt

tubercle, the margins of the head much contracted between the

tubercles and the eyes.

e. Gills (Pig. 59) without cuticular pigment, one-third as broad

as long, the margins thickly provided with setae which extend

from the base to the apex of the gills AmpMagrion.

ec. Gills with cuticular pigment, not more than one-sixth as broad

as long, the margins sparsely setose CTiromagrion.

bb. Caudo-lateral angles of the head not projecting and forming a

blunt tubercle, the margins of the head not contracted between the

tubercles and the eyes.

c. Gills with the tracheal branches much more numerous at the

widest portion of the gill Nelialennia.



500

cc. Gills witli the traclual branches equally distributed throughout
the leiifjth of the y;ill.

d. Gills with long, tapering points, the cutieular pigment, if

present, always in cross-bands; mental setae of the labium
usually four.

e. Gills without cutieular pigment (Fig. 60) ; lateral keels with-

out setae ; n.vniphs of small size, full-grown individuals

rarely more than 14 mm. in length including gills

Anomalagrion.

ee. Gills usually with cutieular pigment in the form of arcuate

cross-bands ; lateral keels with several rows of small setae

;

nymphs larger, when full-grown 18-20 mm. in length in-

cluding gills Ischnura.

dd. Gills with blunt points (Figs. 56, 57, 70-72, 75-77a, 80), or

if with long points, then with cutieular pigment other than in

cross-bands; mental setae usually three (four in E. calverti

and E. cyatJiigerum) Enallagma.

ADULTS

a. Cephalic row of setae of all tibiae twice as long as the spaces between
their bases

;
postnodal cross-veins of the front wings twelve or more

in number; Mo arising between postnodal cross-veins five and nine

in the front wing Argia.

aa. Cephalic row of setae of all tibiae less than twice as long as the

spaces between their bases
;
postnodal cross-veins of the front wings

usually less than twelve in number ; M„ arising between the third and
fifth, rai'ely sixth, postnodal cross-veins in the front wing,

b. Dorsum of the thorax metallic green or bronze ; female pronotum
with the caudal lobe trilobed NeJiaUnnia.

bb. Dorsum of the thorax not metallic green or bronze ; female pro-

notum not with the caudal lobe trilobed.

e.Postocular spots wanting; mesopleural suture without a distinct

black stripe, the sti'ipe not wider than the suture itself.

d. Dorsum of abdominal tcrga 1-6 reddish or buff ; width of the

stigma measured between costa and Sc„-|-R, much greater than

its length ; female with a heavy spine on the caudal margin of

the eighth sternum Amphiagrion.

dd. Dorsum of abdominal terga 1-6, black ; w^dth of the stigma

measured between costa and Scn+Ri not greater than its length

;

female without a heavy spine on the caudal margin of the

eighth sternum Cliroviagrion.

ce. Postoeular spots present ; mesopleural suture usually with a dis-

tinct black stripe, the stripe wider than the suture itself.



501

d. Mo ai'ising between the fourth and sixth pcstnodal cross-veins

in the front wing and between the third and fourth in the

hind Enallagma.

dd. Mo arising between the third and fourth postnodal cross-veins

in the front wing and between the second and third in the hind.

c. Dorsum of the fourth abdominal tergum black, except a

narrow basal ring; stigma of the front wing of the male

not remote from the margin IscJinura.

ee. Dorsum of the fourth abdominal tergum orange or yellow

with the exception of a basal and apical spot in the male

and a small apical spot in the fcnuile; stigma of the front

wing of the male remote from the nuirgin {Fig. 83)

Anomalagrion.

Genus Argia Rambur

The nymphs are characterized by the short thickset form, the

abdomen being as a rule much shorter than that of closely allied genera.

The labium is broad at the proximal end of the median lobe and the

median process of the proximal palpal segment consists of a simple

hook similar to the mesal hook of the same segment. The gills are broad

and oval to elliptical in outline, are heavily pigmented, and the legs

are long and slender, with a number of dark brown rings on the fem-

ora and tibiae. The body is dark in color for the most part, and the

species live either in the mud on the bottom of sluggish streams or

under rocks or debris in the swifter currents.

The adults are distinguishable from other genera by the dorsal

carinae of the femora and the long setae of the front tibiae ; by the

point of origin of vein Mo, which is always beyond the fifth postnodal

cross-vein, and by the number of postnodal cross-veins of the front

wing, the latter ranging from twelve to seventeen in number. The
parameres of the ninth sternum of the male extend caudad to the apex

of the segment, and the sternites at the base of the cephalic pair of

gonapophyses are distinct and subtriangular.

Key to Species

NYMPHS

a. Labial palpi with a single weak seta on the proximal segment ; gills

broad at the tip (Pig. 58), the margins parallel for a considerable

distance, and without light cross-bands and not coarsely spotted

with dark pigment moesta putrida.

aa. Labial palpi with two or more setae on the proximal segment
;
gills

tapering to a point, the margins not parallel or parallel for only a



502

short distance (Figs. 63, 67, 68), and frequently with one or more
light cross-bands and coarsely spotted with dark pigment.

b. Gills broadest beyond the middle, decidedly ovate (Fig. 63) and
frequently with a V-shapod cross-band near the apex ; median lobe

projecting between and distad of the articulations of the labial

palpi much less than one-third the length of the proximal segment
of the palpi (Fig. 11) violacea.

bb. Gills broadest at middle, elliptical (Figs. 67, 68) and never with
a V-shaped mark near the apices; median lobe of the labium pro-

jecting between and distad of the articulations of the labial palpi

one-third or more of the length of the latter ( apicalis.

1 tibialis.

ADULTS

Females

a. Wings smoky fumipennis.

aa. Wings not smoky.

b. Stigma surmounting more than one cell in the hind wing ; mes-

epimera without a broad dark stripe on each, ventrad of the mes-
opleural suture ; mesostigmal plates (Pig. 154) with a sharp median
projection on the caudal margin moesta putrida.

bb. Stigma surmounting a single cell or less in the hind wing ; mes-
epimera with or without (apicalis) a broad dark stripe on each,

ventrad of the mesopleural suture; mesostigmal plates without a
sharp median projection on the caudal margins.

c. Front, vertex, and occiput wholly brown ; caudal margins of the

mesostigmal plates forming a thin blade which projects dorsad. .

.

; sedula.

cc. Front, vertex, and occiput with more or less black pigment

;

caudal margins of the mesostigmal plates not forming a thin

blade which projects dorsad.

d. Black stripe of the mesopleural suture extending more than
half-way to the wing bases from the infraepisternum.

e. Caudal margins of the mesostigmal plates (Fig. 140) not pro-

jecting caudad at the caudo-mcsal angles; terga 1-5 of the

abdomen with the mesal pale line narrower than the black

lines on either side tibialis.

ee. Caudal margins of the mesostigmal plates projecting caudad
at the caudo-mesal angles and forming a rounded lobe (Fig.

142) ; terga 1-5 with the pale mesal stripe much broader

than the black stripe on either side violacea.

dd. Black stripe of the mesopleural suture extending less than half-

way to the wing bases from the infraepisternum apicalis.



503

Males

a. Wings smokj- fumipennis.

aa. Wings not smokj\

b. Stigma surmounting more than one cell in both wings ; abdominal
terga 8-10 black with dorsal spots of brown, or entirely black

moesta putrida.

bb. Stigma surmounting one cell or less; terga 8-10 inclusive or nine
and ten, blue, never black except the eighth, and never with brown
markings.

c. Terga nine and ten blue sedula.

cc. Terga eight, nine, and ten blue.

d. Black stripe of the mesopleural suture extending from the

mesinfraepisternum to the wing bases.

e. Terga 1-5 with the pale color of the dorsum limited to a
very narrow mesal line and narrow basal rings tibialis.

ee. Terga 1-5 with the pale color of the dorsum occupying the

greater portion of the segments, the black confined to small,

apical, lateral spots on 1-4 and an apical ring in addition on
the fifth ' violacea.

dd. Black stripe of the mesopleural suture extending much less

than half-wa.y from the mesinfraepisternum to the wing bases.

.

apicalis.

Argia apicaus (Say)

Nympli.—Color, dark brown.

Head one-third wider than long, pentagonal, the caudo-lateral

angles strongly projecting and armed with heavy setae; eyes black;

antennae dark brown except the first and the last two or three seg-

ments ; labium very broad, the median lobe dark in color, without
mental setae but with about twelve marginal setae; labial palpi with
three or four setae on the proximal segment and with a long movable
distal segment much longer than the fixed hooks; labium, when folded,

extending caudad of the procoxae, but not reaching the mesocoxae.
Thora.x dark in color; legs conspicuously banded, the dark por-

tions consisting of the second segment of the trochanters, two broad
bands on each femur and three on each tibia, the proximal one on
the tibiae being narrow, the next one slightly broader and located

about the middle, and the third nearly equal in width to the median
band and covering the apex; tarsi of the usual form, dark brown in

color ; wing-cases extending caudad to the middle of the fifth abdominal
segment.



504

Abdomen half as broad as long, dark brown in color, the dorsum
with a pale median stripe which widens noticeably on segments eight,

nine, and ten; gills (Fig. 67) elliptical, smoky, frequently possessing

one or two pale transverse bands and usually with a number of

coarse spots of pigment ; apices of the gills bluntly pointed, the margins

hairy, but without heavy setae; ovipositor of the female extending to

the apex of segment ten.

Measurements

Length 14 mm.
Length of abdomen 8 mm.
Length of gills 6 mm.
Width of gills 3 mm.
Length of metathoracic wing-cases. . .4.5 mm.
Length of median lobe 3 mm.
Width of median lobe 1-2 mm

Adult; Male.—Color, light blue (light amparo blue), or bnfi

(warm bufif) and black.

Head : exposed portions of the mouth-parts buff or light blue,

the median lobe of the labium subtriangular, the cleft shallow and

obtuse at the proximal end; proximal segment of the labial palpus

about three times as long as the distal segment ; fixed hook only

slightly longer than the distal segment, black; distal segment black;

antennae black with the exception of the first segment which has a

pale lateral stripe ; clypeus ancl labrum, genal region, exposed portions

of the mandibles, and the front dorsad to the level of the lateral ocelli,

blue ; vertex black ; ocellar area black, the latter sending a black line

ventrad to each antenna; postocular spots present, circular, blue or

brown ; occiput and postgenae yellow with the exception of small black

spots on the postgenae, near the ventral margins of the compound
eyes.

Thorax light blue or buff, black, and sulphur yellow
;
prothorax

black and blue ; caudal lobe of the pronotum black, median lobes with

circular blue spots ; noto-epimeral suture indistinct
;
proepimera blue

or buff, the dorsal margins black; mesopleura and metapleura blue

or olive-buff, and without black markings except a short stripe covering

the dorsal half of the mesinfraepisternum, which extends caudad on

the mesepimeron for about one-fifth of the length of that sclerite;

postcoxal areas buff or yellow; legs striped with black and yellow, a

stripe on each side of the femoral carinae and one on each tibia en-

closing the cephalo-ventral row of setae; tarsi black, the second and



505

third segments frequently yellow above ; wings with twelve to four-

teen postnodal cross-veins, the stigma surmounting a single cell or

less, and Mo arising between the seventh and eighth, or eighth and
ninth, postnodal cross-veins in the front wing and between the sixth

and seventh in the hind wing.

Abdomen blue or buff and black, the black placed as follows

—

a spot on the first tergum, longitudinal dorsal stripes on i-y which

extend well onto the lateral surfaces of terga 3-7 at their apices, and
the lateral margins of terga 8-10 inclusive; the yellow or blue forms
lateral stripes of pale color on terga 1—7, narrow basal rings on 3—7
inclusive, and narrow apical ring on one; dorsum of terga 8-10 blue;

anal appendages (Figs. 151, 152) consisting of short black superiors

and longer bifurcate inferiors, the dorsal emargination of the tenth

tergum about one-third the length of the segment; sterna 2—10 black,

one, pale buff.

Female.—Color similar to that of the male.

Head : cephalic aspect entirely blue or buff with the exception of

black spots ventrad and dorsad of the lateral ocelli and black rings

around the postocular spots.

Thorax as in the male, though usually somewhat lighter in color

;

mesostigmal plates as shown in Figure 153 with a very small caudal

projection near the caudo-mesal angles; caudal lobe of the pronotum
with more or less blue or buff and the mesopleural dark stripes of the

infraepisternum and epimeron paler than those of the male.

Abdomen with the dorsum of the eighth and ninth terga black

with a dorsal yellow stripe and with dark brown or yellow on the

lateral surfaces; tenth tergum dark brown above, paler on the sides,

the dorsal, median emargination extending nearly to the base of the

segment ; anal appendages of the usual form and pale in color ; ovi-

positor with light brown lateral valves, the prostyles darker.

Measurements

Length, $ 38 mm.
Length, 9 36 mm.
Length of abdomen, $ 30 mm.
Length of abdomen, 9 28 mm.
Length of hind wings, S 24 mm.
Length of hind wing.s, 9 23 mm.
Width of hind wing.s, $ 5.5 mm.
Width of hind wings, 9 5.5 mm.

A common species along all large-sized streams in Illinois. The
nymphs live in the mud at the bottom, l)ut when mature approach the



506

banks and hide among dead sul)merged weeds or rubbish. The eggs
are deposited below the water on driftwood, and large numbers of

females may sometimes be seen congregated alxnit an old log at the

water's edge depositing eggs.

Argia FUMiPENNis (Burineister)

Nymph.—Unknown.
Adult; Male.—Color, dull brown and black.

Head: dark brown and black; median lobe of the labium I^uff,

subtriangular ; antennae brown, the first segment nearly globular, the

second segment about twice as long as the first ; clypeus, labrum, ex-

posed portions of the mandibles and their trochantins, genae, and the

front dorsad of the clypeus to the median ocellus, dark brown or buff;

Aertex with a transverse black stripe whicli includes the ocellar area;

there is, however, a large brown spot ventrad of each lateral ocellus and
a narrow median stripe between them

;
postocular spots large, con-

tiguous with the margins of the comjx)und eyes and connected by
means of a broad stripe caudad of the ocelli; occiput and postgenae

buff ; compound eyes brown.
Thorax dark brown, black, and buff; pronotum dark, the cephalic

lobe buff, the median lobes with large, pale, lateral spots ; caudal lobe

dark, with a paler spot on each lateral angle; proepimeron and pro-

epistermun of the propleura not distinct, brown in color, the dorsal

border darker; dorsal carina of the mesothorax covered by a broad

black stripe which also covers about half of each mesosupraepisternum

;

mesepimera with a broad dark stripe ventrad of the mesopleural suture,

the stripe extending cephalad across the infraepisterna and forking

about half-way from the infraepisternum to the wing bases; margins

of the paraptera dark brown, the remainder buff'; metapleural suture

with a dark line; remainder of the meso- and metapleura and the

postcoxal areas buff; femora each with a broad dark brown or blackish

line, the remainder buff; tibiae pale buff above, darker below, the dark

brown color including tlie cephalo-ventral row of setae; w^ings dis-

tinctly tinged with brown
;
postnodal cross-veins sixteen in the front

wing and fifteen in the hind; Mo arising between the seventh and

eighth postnodal cross-veins in the front wing and between the sixth

and seventh in the hind wing; stigma surmounting a single cell or less.

Abdomen dark brown; dorsum of terga 1-7 dark brown, the

lateral margins paler in color; narrow basal rings on the cephalic

margins of terga 3-6 ; terga 8-10 bluish green ; sternum one buff, 3-10
brown; anal appendages (Figs. 143, 144) with the superiors shortest,

inferiors longer, thickset.



507

Female.—Color similar to that of the male.

Head and thorax similar to those of the male except that the color

is paler.

Abdomen : terga 8—g, inclusive, brown with a median buff stripe

and a lateral stripe on each side; tergum ten, buff; ovipositor buff, the

prostyles short and extending caudad of the anal appendages.

Measurcm(:nt>i

Length, $ 33 mm.
Length, 2 34 mm.
Length of abdomen, $ 27 mm.
Length of abdomen, 2 28 mm.
Length of hind wings, $ 20 mm.
Length of hind wings, 2 23 mm.
Width of hind wings, S 5.0 mm.
Width of hind wings, 9 5.5 mm.

This species has not Ijeen reported from Illinois but has been re-

[lorted from Kentucky, and may possibly be taken in southern Illinois.

Described from specimens in the Bolter Collection of the Uni-

versity of Illinois and others in the collection of Mr. E. B. William-

son,—all from Florida.

Argia moesta putrida (Hagen)

Nymph.—Color, dark brown.

Head broad and flat, pentagonal, the caudo-lateral angles project-

ing caudad and possessing a few short setae ; antennal segments dark

except the first, which is pale ; labium very broad, the median lobe but

slightly narrowed at the base and projecting strongly between the labial

paljii ; mental setae wanting, the lateral marginal setae about twelve;

labial palpi with two fixed hooks, both shorter than the sharp distal

segment, the one adjacent to that segment shortest ; setae of the labial

palpi reduced to a single weak hair-like one.

Thorax brown ; the pronotum projecting strongly laterad ; legs

not conspicuously banded as in apicalis, but possessing a faint preapical

ring and with the proximal two-thirds evenly infuscated; tibiae with

dark apices; tarsi mostly pale; femora with indefinite rows of short

heavy setae; wing-cases extending to the middle of the fourth abdom-
inal segment or beyond.

Abdomen uniform brown, the lateral keels feebly developed and
williout setae ; styli of the male very long, nearly reaching the apex of



08

the tenth alKloiuiiial sej,''ment and setose on the ventral margin; apical

margin of the tenth alxlominal tergum cleft nearly to the base, the

margin thicklv beset vvitli short spines; gills (Fig. 58) nniform dark

gray or nearly black, paler at tiie tip, long, broad, and liluntly pointed,

the margins parallel for a considerable distance.

Mcdsurcmcnls (iioun;/ )nfniplis)

Length 14 mm.
Length of abdomen 9 mm.
Length of gills 5-6 mm.
Width of gills 3 mm.
Length of metathoraeic wing-cases ... 4 mm.
Length of median lobe 3.5 mm.
Width of median lobe 1.5-3 mm.

Described from a male specimen in the collection of the Illinois

State Laboratory of Natural History taken from the Kankakee River

six miles below Kankakee, June i, 1901, and several specimens ob-

tained from Dr. E. M. Walker.

Adult; Male.—Color, black and cinnamon-bufT.

Head: median lobe of the labium bufif, subtriangular ; distal seg-

ment of the palpus dark at the tip; antennae black, first two segments

nearly equal, tlie first pale at the apex, the third segment longest ; clyp-

eus and labrum Iniff, the postclypeus with two indefinite black spots

near the fronto-clypeal suture ; labrum with a mesa! spot on the dorsal

margin ; front and genae buff, the pale color extending dorsad to the

ocelli, the black confined to an indefinite ring around the median ocellus

and wedge-shaped marks on the vertex ; occiput black ; the surface

of the head dorsad of the postclypeus and the occiput often becomes
pollinose and obscures the original coloration.

Thorax : prothorax dark brown or black, more or less pollinose

with age; caudal lobe of the pronotum black, median lobes each with

a large, pale, circular, median spot which often becomes pollinose be-

fore the rest of the notum
;
proepimeron pale, the noto-epimeral suture

indistinct though marked by a black stripe ; dorsal carina black and
a black strijjc on each side one-half the width of the mesepisterna;

mesopleural suture lined with black ; mesepimera with a broad sooty

line extending the entire length of the sclerite and more than half as

wide; metapleural suture lined with black, the metepisterna and mete-

pimera and the postcoxal areas usually buff; legs rather short, striped,

the dorsum of all femora with a broad stripe including the cephalo-

ventral row of setae; tarsi and claws black; wings clear, the stigma



509

surmounting cme and one-half to two cells, the postnodal cross-veins of

the front wing sixteen or seventeen, of the hind wing fourteen or fif-

teen ; Mo arising betweeia the sixth and seventh or seventh and eighth

postnodals in the front wing and between the fifth and sixth in the

hind wing.

Abdomen black, with pale basal rings on segments 3-7 inclusive,

faint dorsal and lateral stripes on one and two, and obscure brownish

marks on the last two segments; anal appendages (Figs. 157, 158)
consisting of short club-like superiors and broad inferiors with a

tubercle on the dorsal margin.

Female

.

—Color, light blue (etain blue) or oli\-e-buff, and black.

Head, with front, genae, and verte.x p.ile blue or Initf.

Thorax light blue or buff; pronotuni blue and black, the propleura

with indistinct noto-epimeral suture and without the dorsal marginal

line of brown ; median lobes of the notum with a large pale spot on
each, and another spot about the same size covering the caudo-mesal

angles of the median lobes and the median portion of the caudal lobe;

mesostigmal plate (Fig. 154) with a short, median, acute process

which projects caudad over the cephalic margin of the mesepisternum

;

mesepimera without the broad, longitudinal, dark stripe of the male,

usually blue except the cephalic shoulder which is buff and frequently

pollinose; all of the pleural sutures and the dorsal carina lined with

black.

Abdomen black and blue, the black confined to rather broad dorsal

stripes on terga 1-9, black spots on the caudo-lateral margins of 2-6
and the whole of sterna 1-8; segments nine and ten, with the exception

of a dorsal brown stripe, and the lateral valves of the ovipositor yel-

lowish ; dorsal margin of the tenth tergum with a deep mesal emargina-
tion extending nearly to the base of the segment ; superior anal ap-

pendages, short, dark, and scarcely longer than the blunt inferiors ; ovi-

])ositor with broad ventrally serrated, lateral valves, the prostyles short

and dark.

Measurements

Length, S 42 mm.
Length, 2 41 mm.
Length of abdomen, S 33 mm.
Length of abdomen, 9 31-32 mm.
Length of hind wings, S 26 mm.
Length of hind wings, 2 26 mm.
Width of hind wings, $ 5.,') mm.
Width of hind wings, 2 5.5 mm.



510

Adults of this species have been taken at Oregon in Ogle County,

at Mahomet in Champaign County, and at Muncie and Oakwood in

Vermilion County, hut the species is not espcci;dly abundant in any of

these localities. The nymphs are reported by Needham ('03) as living

under stones in swift currents and by Kellicott ('99) as living on the

piles of docks in Lake Erie.

Argia sedula (Hagen)

Nymph.—Unknown.
Adult: Male.—Color, blue and black.

Head black and blue, the labium pale blue and buff; palpi narrow.

the second segment dark and shorter than the fixed hook, the cleft of

the median lobe obtuse at the base and shallow
;
postclypeus pale except

a black transverse stripe along the dorsal margin ; anteclypeus, labrum,

exposed portions of the mandibles, a transverse area above the clypeus,

and a spot latero-cephalad of each antenna blue ; lateral ocelli with small

yellow spots laterad of each, the remainder of the front and vertex

being black
;
postocular blue spots large and contiguous with the mar-

gins of the compound eyes; occiput and postgenae, with the exception

of rather narrow black stripes caudad of each postocular spot, vellow-

ish buff.

Thorax: pronotum largely black, the median lobe with large sub-

circular spots and the caudal lobe with a pale spot on the extreme

lateral angles, blue
;
proepimera and episterna blue ; mesostigmal plates

subtriangular, not projecting caudad ; dorsal carina of the mesothorax

covered by a broad black stripe which also covers about one-half of

each mesepisternum and is followed by a broad blue stripe which cov-

ers the rest of the mesepisterna ; the blue mesopleural stripe is wider

adjacent to the mesostigma and is gradually narrowed caudad; the

mesopleural suture is covered by a broad black stripe which also covers

most of the mesepimera except the cephalo-ventral shoulders, and is

considerably widened adjacent to the wing bases, enclosing a small blue

spot ; ventral half of the mesinfraepisterna yellow, the remainder black

;

metapleural suture with a narrow black line from wing bases to the

metathoracic spiracles; remainder of the pleura and the postcoxal areas

pale blue or buff ; legs blue and black, the coxae pale, the trochanters

black above, the femora black above and pale below, the front femora,

however, with more or less black between the rows of setae ; tibiae black

below, pale above ; tarsi dark brown, the claws bifid at the tip ; wings

with twelve to fourteen postnodal cross-veins in the front wing and

eleven to twelve in the hind ; Mo arising between the sixth and seventh



511

postnodals in the front wing and between the fourth and fifth in the

hind wing, usually nearer the fifth ; stigma surmounting a single cell

;

paraptera dull velvety l)lack.

Abdcjmen blue and black ; basal half and a spot on the sides of the

first tergum black, the remainder blue ; dorsum and apex of the second

black, the lateral margins blue ; basal rings, and lateral marginal stripes,

extending one-half to three-fourths the length of segments 3—6, in-

clusive, blue ; the remainder of these terga, black ; tergum seven except

a small basal ring, black; dorsum of terga eight, nine, and ten blue,

the lateral margins sometimes darker; first sternum with a black, me-
dian spot, 3-10 entirely black; anal appendages short, black, the in-

feriors longest and bifurcate (Figs. 149, 150).
Pcmalc.—Color, brown and black.

Head : front, vertex, occiput, and postgenae dull brown.
Thorax brown, the mesostigmal plates usually black and the

caudal margins forming a thin blade which projects dorsad ; black

spots present on the mesopleural and metapleural sutures adjoining
the wing bases ; legs similar to the male except that the hind pair are

almost entirely pale brown.
Abdomen dull brown, with indistinct touches of blue, very similar

to that of the male except that the basal rings are not as broad or as

well defined; terga 6-10, inclusive, entirely dull brown; anal appen-
dages short ; ovipositor long and slender, extending caudad of the anal

appendages, pale brown in color.

Measurements

Length, $ 30-40 mm.
Length, 9 34 mm.
Length of abdomen, $ 24-27 mm.
Length of abdomen, $ 27 mm.
Length of hind wings, $ 18-19 mm.
Length of hind wings, 9 21 mm.
Width of hind wings-, $ 4-4.5 mm.
Width of hind wings, 9 5 mm.

Described from a large series of males and females in the col-

lection of Mr. E. B. Williamson.

This species has been reported from Illinois.

Argia tibialis (Rambur)

Nymph.—Color, very dark brown.
Head about as long as broad, pentagonal ; eyes black ; antennae

with all segments except the last two dark on the basal three-fourths,



512

the remainder pale; third antennal se,s:ment longest, the second and

fourth about equal, and the first, fifth, sixth, and seventh successively

shorter; caudo-lateral margins of the head without heavy setae;

labium, when folded, extending caudad between the first and second

pair of coxae ; median lolie nearly as broad as long, and with about

twelve marginal setae; lateral setae of the labial palpi two or three.

Thorax about as broad as long; legs with conspicuous brown
jjands, the femora possessing two—a broad basal one and a narrower

preapical one—the tibiae three, one on l)ase, one on apex, and a liroader

one just proximad of the middle; tarsi with the usual ventral setae and

mostly dark; metathoracic wing-cases reaching the apex of the fifth

abdominal segment in mature nymphs.
Abdomen dark, almost black ; lateral keels feebly developed,

hairy ; dorsum of the first to the tenth terga with a pale mesal stripe

which widens slightly caudad though not as conspicuously as in the

nymph of znolacca or apicalis; gills elliptical, sometimes wholly dark,

or smoky, often possessing a broad, transverse, whitish band about the

middle and a narrower subapical one ; margins densely pilose but with-

out heavy setae and the gills frequently coarsely spotted; female ovi-

positor extending to the apex of segment ten.

Measurements

Length 12.5 mm.
Length af abdomen 7 mm.
Length of gills 6.5 mm.
Width of gills 3 mm.
Length of metathoracic wing-cases. . .3.5 mm.
Length of median lobe 2.5 mm.
Width of median lobe 1.25-2 mm.

Adult; Male—Color, dark purple or warm brown, sulphur-yel-

low, and black.

Head blue or Ijrown ; median lobe of the labium brown, the me-
dian cleft short, obtuse at the base; proximal segment of the palpus

rather narrow, the apical segment black and slightly shorter than the

black fixed hook; antennae black with the exception of the apices of

segments one and two, which are pale ; fronto-clypeal suture lined with

brown ; clypeus, labrum, exposed portions of the mandibles and their

trochantins, genae, and front to the level of the median ocellus brown
or blue ; ocellar triangle, vertex, and the occiput, black, the black area

sending a black stripe ventrad from the verte.x to each antenna, and
another enclosing the median ocellus and extending a short distance



513

ventrad where it meets a short transverse black Hne at right angles

;

clypeus and labrum, front and vertex, thinly pilose, the setae whitish

;

compound eyes slate-colored.

Thorax brown or purple and black
;
pronotum with black caudal

lobe ; median and cephalic lobes also black, the median lobes each with

a small lateral brown spot; proepimera brown, with a broad black

stripe above ; mesostigmal plates black ; dorsal carina covered by a black

stripe, the lateral halves of the stripe covering about one-fifth of each

mesepisternum, the stripes widened at the caudal and cephalic ends

and covering the stigmal plates and paraptera ; mesopleural suture cov-

ered with a broad black stripe which is frecjuently forked near the wing

bases, extends cephalad, and covers all of the mesinfraepisterna except

the caudo-ventral angles and one-third of each mesepimeron

;

metapleural suture with a narrow line of black, the metepisterna and

epimera brown or buff
;
postcoxal areas buff, but frequently with darker

lateral margins and a pair of median spots on the intersternum ; legs

mostly black, the coxae yellowish, with black cephalic surfaces, the

femora black with the exception of the dorsal carinae which sometimes

have a pale stripe ; tibiae with a paler dorsal line ; tarsi and claws black

;

anterior femoral setae eight or nine in the cephalic row, two large and

usuallv two small ones in the caudal row ; wings clear, the postnodal

cross-veins twelve to thirteen in the hind wing and fifteen to sixteen

in the front; Mo arising between the seventh and eighth postnodal

cross-veins in the front wing and between the sixth and seventh in the

hind wing.

Abdomen black, with sulphur-yellow and blue; terga i-8, inclu-

sive, black, the vellow confined to lateral spots, narrow basal rings on

2-7, an apical ring on one, and narrow lines on the lateral margins of

terga 2-7 which extend about one-half the length of each segment from
the base and unite with the basal rings in segments three, four, and

five; in older specimens, however, the lateral stripes are obscured by
more or less brown ; dorsum of the eighth and ninth terga, with the ex-

ception of the black apical margin of nine, pale blue ; anal appendages

(Figs. 155, 156) black, the superiors small and black, the inferiors

black but with a paler dorsal spot.

Female.—Color, pale blue (pale methyl-blue) or bufif (ochraceous

buff) , and black.

Head as in the male but lighter in color, the front lacking the

vertical lines above the antennae and the transverse line below the me-
dian ocellus; postocular spots present and a pale transverse line, with

more or less yellow, on the caudo-dorsal margins of the head
;
post-

genae with yellow adjacent to the compound eyes.



514

Thorax blue or brown and black; caudal and cephalic lobes of the

pronotum with more or less blue or ])rown ; mesostigmal plates ( Fig.

140) without projections on the caudal margins; mesopleural stripe of

black, somewhat narrower than that of the male, separating more dis-

tinctly from the suture at the caudal third, the ventral branch fre-

quently stopping short of the caudal margin of the sclcrite ; legs paler

than those of the male, the femora usually witli two dark stripes one

on each side of the carina, the remainder pale l)lue or brown ; tibiae

with a black ventral stripe between the rows of setae which frequently

includes one of the rows; tarsi often with the proximal segments ])ale.

Abdomen : lateral surfaces, apical ring, and narrow mcsal lines of

the first tergum pale, the black confined to two dorsal basal spots ; sec-

ond tergum with broad lateral blue stripes and a dorsal stripe greatly

contracted and then widened again shortly before the apex, the black

limited to a narrow apical ring and a dorso-lateral stripe on each side

;

segments 3—7 as in the male with the exception of a narrower mid-

dorsal pale line ; tergum nine black with a paler narrow apical line, the

tenth yellowish or blue, with a narrow basal ring, the segment usually

dark below ; anal appendages of the usual type, the superiors black or

dark, the inferiors slightly paler in color; ovipositor, except the ex-

treme tip and the prostyles, dark brown or black.

Measui-ements

Length, $ 34-37 mm.
Length, 9 35-37 mm.
Length of abdomen, S 26-30 mm.
Length of abdomen, 9 28 mm.
Length of hind wings, S 20-22 mm.
Length of hind wings*, 9 24 mm.
Width of hind wings, 3 4.5 mm.
Width of hind wings, 9 5 mm.

The nymphs of this species have been taken beneath rocks in

swift currents. A single specimen has been reared and a comparison

of the nymph with the nymph of apiccJis shows them to be almost

identical. Needham ('03) separates the two species on the character

of the lateral setae, but there is so much variation in apicalis that the

character seems without value.

The adults are common throughout the state and may be found
at almost any point along the banks of clear, swift streams.



b

515

Argia violacea (Hagen)

Nymph.—Color, very dark brown.

Head pentagonal, the caudo-lateral angles nearly rectangular and
provided with a few weak setae ; antennal segments all dark except the

proximal one, which is light in color ; third segment longest and the

second longer than the first; labium short and broad, the width about
two-thirds the length ; lateral setae two or three.

Thorax short, dark brown, with a black stripe on each side; legs

with dark coxae and trochanters, a narrow proximal ring on each

femur which is followed by two broad browni.sh rings, the three divid-

ing the femur into fourths; tibiae with narrow proximal rings and
rings of similar size shortly before the middle, the apices dark; tarsi

dark, though not as dark as the rings of the femora and tibiae.

Abdomen dark brown with a paler mesal stripe on the dorso-

meson ; lateral keels feebly developed and without setae on their lateral

margins; gills ovate, more than half as broad as long, uniform brown
or sometimes having paler V-shaped marks near the apices, the mar-
gins thickly covered with setae arranged irregularly; ovipositor of the

female with sharply pointed lateral valves which extend beyond the

tenth abdominal segment.

Measurements

Length 17 mm.
Length of abdomen 7 mm.
Length of gills 4.5 mm.
Width of gills 2.5 mm.
Length of metathoracic wing-cases ... 5 mm.
Length of median lobe 3 mm.
Width of median lobe 1.25-2 mm.

Adult; Male.—Color, dark brown or purple (Matthew's purple).

Head : median lobe of the labium pale ; distal segment of the labial

palpi black at the tip ; antennae black or dark brown except the basal

segment, which is buff ; clypeus and labrum pale brown, the front, ver-

tex, and postocular regions also largely pale but becoming violet with

age, the black confined to a broad transverse band embracing the two
lateral ocelli, a T-shaped mark ventrad of the median ocellus, and nar-

row lines extending from the ends of the transverse band to the com-
pound eyes and to the caudal margins of the head ; caudo-dorsal mar-
gins of the head with a black line; occipital and postgenal regions

largely yellow ; compound eyes, slate-gray.



516

Thorax brown or violet and black ; caudal lobe of the pronotum

black and brown, the brown in lateral spots on the lateral margins

and in a very small median spot ; median lobes each with a large sub-

circular, lateral buff spot; proepimera buff, with dark lines marking

the dorsal border ; mesothorax with a black line on the dorsal carina

a.nd another just ventrad oi the mesopleural suture and contiguous

with the longitudinal portion of the suture for more than one-half its

length; dorsal third of the mesinfraepisternum black; metapleural

suture with a black line; metepimera and postcoxal areas buff; legs

striped, all the femora with a black stripe on each side of the dorsal

carina and the tibiae with a ventral stripe including one of the rows of

setae ; tarsi dark brown or black, the claws also black ; wings clear, the

stigma surmounting a single cell or less, the postnodal cross-veins of

the front wing thirteen to fourteen, of the hind wing ten to eleven

;

M, arising between the fifth and sixth postnodal cross-veins in the

front wing and between the fourth and fifth in the hind wing.

Abdomen purple and black, or brown and black ; first tergum with

a narrow, basal, black, transverse stripe, the second with large lateral

spots extending from the cephalic margin nearly to the apex; terga

three and four brov^'n or purple, with the exception of a caudo-lateral

spot on each side; tergum five with a dark apical ring and narrow

lateral black stripes, the sixth with the purple confined to a dorsal stripe

and a basal ring, the remainder of the tergum black or dark brown;

seventh tergum entirely black, eighth, ninth, and tenth blue on the

dorsum, black on the lateral surfaces; sterna i-io black; anal appen-

dages (Figs. 145, 146) consisting of short blunt superiors and longer

bifurcate inferiors.

Female.—Color, dark brown or dull violet.

Head similar to that of the male.

Thorax: dorsal mesostigmal plates (Fig. 142) with large

rounded lobes at the caudo-mesal angles.

Abdomen with more black than the male ; terga 2-9 with dorso-

lateral stripes which are broad enough on the seventh and eighth terga

to fuse on the meson ; lateral surface of tergum nine and all of ten buff,

dorsal emargination of the tenth nearly reaching the base of the seg-

ment ; anal appendages and ovipositor of the usual type, the lateral

valves of the ovipositor being serrate on the ventral margin, the pro-

styles, dark.

Measurements

Length, S 32 mm.
Length, 9 31 mm.
Length of abdomen, i 24 mm.



517

Length of abdomen, 2 20 mm.
Length of hind wings, 3 20 mm.
Length of hind wings, 9 20 mm.
Width of hind wings, S 4 mm.
Width of hind wings, 9 5 mm.

This species is common at times along the Drainage Ditch north

of Urbana, and the nymphs may be taken at almost any season in the

black mud on the bottom of the stream. The species has not been col-

lected elsewhere in the state and it does not seem to be as common as

reported to be in Indiana. The nymphs emerge throughout June and the

adults fly as late as the first of September.

Genus Enallagma Charpentier

The nymphs of this genus are characterized by the presence of

three, rarely four, mental setae, and five lateral setae. The gills are

variable but do not possess the long tapering points of Ischnura and
Anomalagrion, being relatively blunt at the tip. The lateral keels are

well developed and setose and in some cases present characters of diag-

nostic value for the species.

The adults in all cases have vein Mj arising between the fourth
and sixth, usually fourth and fifth, postnodal cross-veins in the front

wing and between the third and fifth in the hind wing. The number
of postnodal cross-veins varies from seven to twelve, and the female
always has a long apical seta on the eighth sternum. The eighth

sternites at the base of the cephalic pair of gonapophyses of the female
are visible and are small and subtriangular.

The genus is represented in Illinois by more species than any other

genus of Zygoptera.

Key to Species

NYMPHS

a. Gills without pigment except in the tracheae.

b. Dark tracheal branches in alga-like patches (Fig. 76) Jiageni.

bb. Dark tracheal branches not in alga-like patches.

e. Lateral keel of the first abdominal segment without setae ; axis of
the gills clear.

d. Dorsal marginal setae of the median gill less than twenty in

full-grown nymphs; all of the third antennal segment dark
brown; gills rarely more than 4.5 mm. in length (Fig. 72) ....

geminatum.



518

dd. Dorsal marginal setae of the median gill more than twenty in

full-grown nymphs; only the proximal thii-il of the thii-d anten-

nal segment dark brown
;
gills eommonly 5.5-6 mm. in length.

.

civile.

ce. Lateral keel of the fii'st al)doniinal segment with two to four

heavy setae; axis of the gills ojtaque or slightly smoky,

d. Dorsal setae of the median gill extending beyond the middle

;

mental setae four, the mcso-caudal seta in each row one-half

as long or nearly as long as the remaining setae. .1 cuathigcrum.

I calvcrti.

dd. Dorsal setae of the median gill not extending to the middle

of the gill; mental setae three, the meso-caudal seta in each

row representing a small fourth, but minute and always less

than one-half the length of the three larger setae, cnrunculntmn.

aa. Gills with pigment other than in the ti-acheae.

b. Tracheal branches of the gills in alga-like patches ; distance from
the caudal margins of the compound eyes to the caudo-lateral angles

of the head greater than half the distance between the antenna!

fossae. Abdomen without a median, ventral, black lise.

c. Dark portion of the base of the gills extending less than half

their length (Fig. 55) travintum.

cc. Dark portion of the base of the gills extending' more than half

their length.

d. Length of the gills less than eight times the greatest width

;

gills of mature nymphs with a prominent hinge just caudad
of the middle (Fig. 53) exsuhins.

dd. Length of the gills eight times the greatest width
;

gills of

mature nymphs without a prominent hinge caudad of the

middle (Fig. 54) antennatum.

bb. Tracheal branches of the gills not in alga-like patches ; distance from
the caudal margins of the compound eyes to the caudo-lateral angles

of the head less than half the distance between the antennal fossae.

Abdomen with a median, ventral, black line.

c. Median gill with a bunch of setae proximad of the first dark
transverse cross-band ; distal cross-bands of the same degree of

blackness as the proximal ones (Fig. 56) ; median gill not greatly

expanded distad of the first cross-band ; dorsal setae of the apical

margins of the abdominal terga not prominent signntum.

cc. Median gill without a bunch of setae proximad of the first dark
transvei'se cross-band; distal cross-bands faint, and lighter in

color than the proximal ones (Fig. 57) ; median gill much ex-

panded distad of the first ci'oss-band; dorsal setae of the apical

margins of the abdominal terga very prominent pollutum.



519

ADULTS

Females

a. Eighth abdominal tergum with a large blue or pale spot on each side

side of the meson.

b. Dorsum of the seventh tergum black (Fig. 96) geminatum.

bb. Dorsum of the seventh tergum blue, never with more than a line

of l>laek on the meson (Pig. 95) aspersum.

aa. Eighth abdominal tergum without a large blue or pale spot on each

side of the meson.

b. Longitudinal dark stripe on the dorsum of the second abdominal
tergum dumb-bell shaped ; caudal half of the eighth tergum black or

dark traviafum.

bb. Longitudinal stripe on the second abdominal tergum not dumb-bell
shaped; apical half of the eighth black or dark,

c. Proximal two-thirds of the second antennal segment pale.

d. Dark stripe of the mesopleural suture reduced in width to a

mere line and much less distinct than the dorsal stripe covering
the carina ; color of the thorax above faint blue (tenei-al) or

lemon-yellow (mature) and black pollutum.

dd. Dark stripe of the mesopleural suture not reduced in width
to a mere line and as distinct as the dorsal stripe covering the

carina; color of the thorax above blue (teneral) or orange
(mature) and black signatum.

cc. Proximal two-thirds of the second antennal segment brown or

black.

d. Dorsum of the tenth tergum dark ; mesopleural black stripe

of the suture not divided by a brown stripe immediately above
the suture; caudal lobe of the pronotum without a median
mound-like elevation.

e. M. arising beyond the fourth postnodal cross-vein in the

hind wing.

f. Mesostigmal plates with a diagonal ridge from the caudo-
mesal to the cephalo-lateral angles carunculatum.

ff. Meso.stigmal plates without a diagonal ridge from caudo-
mesal to cephalo-lateral angles.

g. Black color of dorsum of abdominal terga 4r-l always
reaching the cephalic margins (Fig. 92).

h. Mesal half of the caudal margins of the mesostigmal
plates convex (Fig. 212) civile.

hh. Mesal half of the caudal margins of the mesostigmal
plates concave (Fig. 226) doubledayi.



520

gg. Black color of the ilorsuni of abdominal terga 4-7 never
reaching the cephalic margins.

h. Cephalo-mcsal angles of the inesostigmal plates

rounded and hollowed out (Fig. 213) . . .cyathigerum.

hh. Cephalo-mesal angles of the mesostigmal plates not
rounded or hollowed out (Fig. 223) calverti.

ee. Mj arising between the third and fourth postnodal cross-

veins in the hind wings.

f. Mesostigmal plates narrowed at middle (Fig. 227) .ebrium.

ff. Mesostigmal plates considerably widened at the middle
(Fig. 221) " hngeni.

dd. Dorsum of the tenth tergum pale ; mesopleural black stripe

divided by a bi'own stripe innnediately above the suture ; caudal
lobe of the pronotum with a median mound-like elevation (Figs.

219,220).

6. Caudal margin of the mesostigmal plates at right angles to

the dorso-meson exsulans.

ee. Caudal margin of the mesostigmal plates not at right angles

to the dorso-meson I antcnnatuni.

\ divagans.

Males

a. Dorsum of the second abdominal tergum with an apical spot occupy-

ing at most half of the segment ; i-emainder of the tergum blue,

b. Lateral surface of the second abdominal tergum with a short lon-

gitudinal brown or black stripe gcminatiun.

bb. Lateral surface of the second abdominal tei'gum without a short

longitudinal brown or black stripe.

c. Caudal half of the seventh abdominal tergum blue
;
postocular

spots connected with the blue of the occiput aspersum.

cc. Caudal half of the seventh abdominal tergum black
;
postocular

spots not connected with the blue of the occiput,

d. Dorsum of the fourth and fifth abdominal terga more than

half black cnrunculafum.

dd. Dorsum of the fourth and fifth abdominal terga less than half

black.

e. Superior anal appendages bifurcate ebrium.

ee. Superior anal appendages not bifurcate.

f. Inferior anal appendages longer than the superiors,

g. M„ ar-ising between the third and fourth postnodal cross-

veins in the hind wings liageni.

gg. M2 arising between the fourth and fifth postnodal cross-

veins in the hind wings.



521

h. Superior anal appendages blunt ; lateral profile as

shown in Fig. 200 calverti.

hh. Superior anal appendages acute ; lateral profile as

showni in Fig. 201 cyathigerum.

ff. Inferior anal appendages shorter than the superiors.

g. Superior anal appendages with the apical tubercles pro-

jecting noticeably beyond the dorso-caudal angles when
viewed from the side (Fig. 175) doubledayi.

gg. Superior anal appendages with the apical tubercles not
projecting noticeably beyond the doi'so-caudal angles

when viewed from the side (Fig. 198) civile.

aa. Dorsum of the second abdominal tergum wholly black.

b. Second antennal segment pale except the distal third, which is dark
brown or black.

c. Dark stripe of the mesopleural suture paler in color than the

dorsal stripe covering the carina and often reduced to a mere
line pollutum.

ec. Dark stripe of the mesopleural suture not paler in color than
the dorsal stripe covering the carina and never reduced to a line

signatum.

bb. Second antennal segment entirely dark brown or black.

c. Front with the blue color extending dorsad to the median ocellus

;

postocular spots forming an equilateral triangle; black stripe of

the mesopleural suture indistinct or wanting traviatum.

ce. Front with the blue or pale color not extending dorsad to the me-
dian ocellus, not dorsad of the antennal fossae

;
postocular spots

forming a Avedge-shaped figure; black stripe of the mesopleural
suture distinct, never wanting.

d. Superior anal appendages bifurcate.

e. Dorsal arm of the superior appendages shortest ; arms not

widely divaricate (Figs. 203, 210) exsulans.

ee. Dorsal arm of the superior appendages as long as the ventral

;

arms widely divaricate (Figs. 202, 209) antennatum.

dd. Superior anal appendages not bifurcate (Figs. 190, 197)

divagans.

Enallagma antennatum (Say)

Nymph.—Color, brown or greenish.

Head about half as long as wide, the caudo-lateral angles project-

ing strongly caudad and thickly studded with setae; seconci antennal

segment slightly shorter than the first, the first two segments dark and
pilose; labium with three mental setae, four or five lateral ones, and



522

with seven or eight setae on the laternl margins of the median lobe;

labium extending just caudad of the first pair of coxae.

Thorax about half as wide as the head; the femora all with pre-

apical rings on the distal third ; til)iae with the usual apical scales ; tarsi

pale ; metathoracic wing-cases extending beyond the cephalic margin of

the fourth abdominal segment.

Abdomen slender, the lateral keels well developed on segments
1—8 but almost wholly lacking in setae except the seventh, which some-
times possesses a single weak one; gills (Fig. 54) long and slender,

somewhat lanceolate, with a gradually tapering tip ; the smaller

tracheae are collected in alga-like patches, and the gills are always pro-

vided with some dark cuticular pigment ; there is a light spot on the

apical third or fourth of the gill on each side of the axis as in cxsidans

which is often followed by two dark cross-bands, the extreme tip, how-
ever, being light in color ; female ovipositor extending to the middle of

the tenth sternum.

Mmsuremenis

Length 13-14 mm.
Length of abdomen 9 mm.
Length of gill.s 7-8 mm.
Width of gills 1-1.3 mm.
Length of metathoracic wing-cases ... 4 mm.
Length of median lobe 1.6 mm.
Width of median lobe 5-1.2 mm.

The nymph is very similar to cxsidans but may be distinguished

from that species by means of the more slender gills, the cross-bands

at the tij) in older individuals, and l\v the absence of a hinge beyond

the middle.

Adult; Male.—Color, blue or greenish yellow and black.

Head black and orange; mouth-parts buff, the median lobe of the

labium subtriangular, the median cleft shallow, acute
;
proximal seg-

ment of the palpus comparatively narrow, the apical half of the distal

segment dark; antennae dark, the apex of the first two segments some-

times lighter in color; a large portion of the postclypeus and a dorso-

mesal spot on the labrum, black ; anteclypeus, the remainder of the

labrum, exposed portions of the mandibles, their trochantins, the genae,

and a transverse stripe above the clypeus orange ; remainder of the

front and vertex dull black
;
postocular spots cuneiform, connected with

the narrow stripe of the caudo-mesal margin ; occiput and postgenae

yellow except a black stripe caudo-ventrad of the postocular spots;

compound eyes slate-gray.



523

Thorax yellow or blue, and black ;
pronotum blue and black, the

cephalic lobe largely blue, the median lobes black with small lateral blue

spots and with median spots, but only in very recently emerged speci-

mens ; caudal lobe of the pronotum with a small, pale, mesal spot, the

remainder black; mesostigmal plate with a pale lateral spot and a

smaller spot on the caudo-mesal angle ; dorsal carina lined with blue,

on each side of which there is a broad black stripe occupying about half

or more of each mesepisternum ; beyond these dorsal stripes on the

mesepisterna there are narrow, pale stripes; mesopleural suture cov-

ered by a broad black stripe which extends cephalad onto the mesinfra-

episternum and covers one-third of it ; interpleural fold with a black

dash near the wing bases ; remainder of the thorax pale greenish yel-

low.

Abdomen black, greenish yellow, and blue; terga 1-8, inclusive,

and ten with black dorsal longitudinal stripes, the stripes widened sub-

apically on segments 2-5, inclusive, and narrowed to the meson at the

apex of eight ; apical black rings on terga 2-5 and on eight ; lateral sur-

faces of terga 1-8, inclusive, with basal interrupted rings except on the

first, which has an apical pale yellowish green ring ; lateral sur-

face of the eighth tergum and all of the ninth blue; sterna 2-8 with a

black ventral mesal line; superior anal appendages (Figs. 202, 209)
black, bifurcate, the arms about equal and widely divaricate; the in-

feriors shorter, directed obliquely dorsad, mostly buff, the tips black.

Female.—Color similar to that of the male.

Head similar to that of the male.

Thorax similar in color to that of the male
; prothorax with a small

spot on each median lobe near the mes(5n, besides the lateral ones, and
the mesopleural black stripe more commonly divided by a brown line

immediately over the suture.

Abdomen : terga i—10 with broad dorsal brown or black stripes,

the stripes widened subapically on segments two to six and continuous
with a dark apical ring on the same segments ; tergum nine with a nar-

row pale line, sometimes diamond-shaped ; lateral surfaces of terga

2-7 inclusive, greenish yellow; sterna 1-7 or 1-8 with a black mesal
line; eighth sternum with a very long and heavy apical seta and the

anal appendages of the usual type; ovipositor including the prostyles

not extending caudad of the anal appendages, the ventral margins of

the lateral valves serrate; eighth sternites small, triangular.

Measurements

Length, S 34 mm.
Length, 2 32 mm.



524

Length of abdomen, S 28 mm.
Length of abdomen, $ 25 mm.
Length of hind wings, $ 19 mm.
Length of hind wing.s, V 19 mm.
Width of hind wings. $ 4 mm.
Width of hind wings. $ 4 mm.

A relatively rare species which has not been collected outside of

Champaign County. The nymphs are to be found in the same locrdity

where c.vsulaiis is abundant and the two are freciuently taken together.

EnaUvAGma aspeksum (Hagen)

Nymph.—Unknown.
Adult; Male.—Color, blue and black.

Head blue and black ; mouth-parts buff, the median lobe subtrian-

gular and with a shallow acute cleft
;
palpi narrow, the distal segment

pale ; antennae black
;
postclypeus black, anteclypeus and the labrum

brown or buff and a blue transverse stripe above the clypeus to the level

of the antennal fossae; remainder of the front and vertex black; post-

ocular spots blue, the blue connected with the blue of the occiput and

postgenae.

Thorax blue and black
;
pronotum black except the narrow- cephalic

lobe, which is blue; proepimera black alcove, blue or pale below; meso-
stigmal plate narrow and about half blue ; niesothorax with a broad

dorsal stripe, covering the carina and also half of the mesosupraepi-

sterna on either side; this is followed by a blue stripe 'which occupies

most of the remaining portion of the mesosupraepisternum ; meso-
pleural suture covered with a black stripe which is considerably

widened near the caudal margin of the mesinfraepisternum and extends

cephalad over that sclerite, covering the dorsal half or third ; remainder

of the thorax blue or buff: paraptera entirely black; legs black and
buff, the coxae and the trochanters pale, the femora with a stripe on
the cephalic surfaces including one row of setae ; tarsi and claws black,

shining; wings with nine postnodal cross-veins in the front wing and
eight in the hind wing; Mo arising between the fourth and fifth post-

nodal cross-veins in the front wing and between three and four in the

land wing.

Abdomen blue and black ; terga mostly blue, but a very narrow
Ijasal spot on the first tergum, a dorsal apical spot and ring on the

second, the apical three-fourths of the dorsum of the third, dorsum
of the fourth, all of five and six except narrow basal rings, the proximal

lialf of seven, and all of the dorsum of ten, are black; lateral margins



525

of the fourth, fifth, and sixth terga are mostly pale yellow; anal ap-

pendages (Fig. 195) black, the superiors much longer than the in-

feriors and with a ventral basal tubercle, the apices blunt and directed

ventrad; inferiors conical, sharply pointed, and directed obliquely

dorsad.

Female.—Color similar to that of the male.

Head similar to that of the male except that the postocular spots

are not connected with the blue of the caudal portion of the occiput.

Thorax similar to that of the male ; mesostigmal plates black.

Abdomen (Fig. 95) with terga 1-6 as in the male, seven with

dorsal stripe reduced to a mesal line on the basal three-fourths, sud-

denly widened at the apex; eighth tergum black, with a pair of pale

basal spots connecting with the pale lateral margins ; dorsum of nine

and ten black, the lateral surfaces pale ; ovipositor short, the prostyles

blunt and dark, the ventral margins of the lateral valves serrate.

Measurements

Length, S 27-32 mm.
Length, 9 34 mm.
Length of abdomen, S 22-25 mm.
Length of abdomen, 9 26 mm.
Length of hind wings, S 16-18 mm.
Length of hind wings, 9 20 mm.
Width of hind wing's, $ 3-3.7 mm.
Width of hind wings, 9 4 mm.

Described from a specimen taken at Lexington, Ky., August,

19 1 5, and a number of both sexes in the collection of E. B. Williamson.

Reported from Illinois.

Enallagma cam'Erti Morse

Nymph.—Color, bufif.

Head subelliptical, the caudo-lateral margins projecting a little

caudad and with a few setae; antennae of the usual form, the third

segment longest, the second longer than the first ; labium extending

caudad to the second pair of coxae ; mental setae four, lateral setae six,

and the marginal setae on the margin of the median lobe five or six.

Thorax : legs with rows of heavy setae, especially prominent on

the femora, which have several rows and a group of longer setae near

the apices ; tibiae with two ventral rows of long setae, and a thick bunch

of scales at the apices; tarsi of the usual form and with thick ventral



526

rows of setae ; nietathoracic wing-cases extending caiulad to the middle

of the fourth abdominal segment.

Abdomen long and slender, uniff)rm bufif, the cuticle provided

with minute setae; segments 3-10 with dorsal transverse rows of setae

at the caudal margins and segments 3-7 with similar ventral rows, the

setae grouped somewhat conspicuously on the meson; lateral keels

strongly developed, setose, the keel of the first segment witli a number

of heavy setae, usually three, that of th.e second with a row of eight or

nine, and keels of the third to the eighth segments with a row of ten or

twelve, and with groups of two or three at the apices ; ninth segment

with a lateral row of setae in line with the lateral keels; gills (Fig. 80)

very long, somewhat spatulate, the points mostly blunt, and the dorsal

marginal row of setae of the median gill extending much beyond the

middle; three narrow transverse bands sometimes occur just beyond

the middle ; the}^ are placed closely together as a rule, but the bands

may be reduced to one or may be wantmg.

Measurements

Length 15 mm.
Length of abdomen 9 mm.
Length of gills 7 mm.
Width of gills 1.8 mm.
Length of median lobe 2.3 mm.
Width of median lobe 8-1.6 mm.

Described from three specimens in the collection of the State

Laboratory of Natural History, collected at Havana, 111., June 30,

1897. '

'

_

The nymph has not been reared, but the specimens were deter-

mined from a description given by Walker.

Adult; Male.—Color, blue and black.

Head blue and black, hufi below; labium bufif, the median lobe

subtriangular, the apical cleft narrow ; distal segment of the labial palpi

pale
;
postclypeus black except the lateral margins, anteclypeus, labrum,

mandibles, their trochantins, genae, and the transverse area above the

clvpeus blue ; lateral ocelli with a small blue spot cephalad of each, the

remainder of the front and vertex black
;
pale line caudad of the ocellar

area distinct, the ends narrowly separated from the large blue, cunei-

form postocular spots ; occiput pale e.xcept a transverse black line bor-

dering the postocular spots.

Thorax blue and black ; pronotum mostly black, with a large blue

spot on each median hjbe, the caudal margin of the caudal lobe and



527

most of the cephalic lobe blue; proepimera blue, the dorsal border with

a broad black stripe ; mesothorax with a blue dorsal carina, the black

stripe on each side occupying about half of each supraepisternum

;

mesopleural suture covered by a black stripe which is suddenly widened

caudad of the infraepisterna; dorsal third of the mesepimeron black;

metapleural suture with a black spot adjacent to the wing bases

;

paraptera black, the cephalic margins blue ; remainder of the pleura

blue
;
postcoxal areas buff ; legs striped black and blue, the coxae largely

blue ; trochanters blue, dark above ; femora with black stripes occupy-

ing the whole of the dorsum, but not extending ventrad far enough to

include either row of setae ; cephalic margins of all femoral black

stripes emarginate at the proximal end ; cephalic half of the tibiae black,

the stripe including the cephalo-ventral row of setae; tarsi uniform
brown, the segments darker at the distal end; wings with 12—13 post-

nodal cross-veins in the front wing and 10—11 in the hind; Mo arising

between the fifth and sixth postnodal cross-veins or near the fifth in

the front wing, and between the fourth and fifth in the hind; stigma
small, pale brown, and surmounting slightly less than a single cell.

Abdomen blue and black; terga 1-5 inclusive, blue with the excep-

tion of a black spot on the dorsum of one, a subapical dorsal spot and
apical ring on two, and apical spots and rings on 3-5 ; caudal half of the

dorsum of six and caudal three-fourths of seven, black; terga eight

and nine blue ; tenth tergum black above, pale buff on the lateral mar-
gins; first sternum pale; sterna 3-8 black; parameres black and not

reaching the apex of the segment; anal appendages short (Figs. 200,

207), the superiors blunt, shorter than the inferiors, but without the

conspicuous tubercle of ciz'ilc and carunadaHim; inferiors slender,

acute and black at the tips.

Female.—Color, blue, but paler than that of the male.

Head : the blue of the male is replaced by brown or buff.

Thorax similar to that of the male, but the blue is frequentlv re-

placed by brown or bufif.

Abdomen blue and black, the first tergum with a black basal spot

as in the male, spot of the second tergum connected with the apical ring

and a line on the meson extending to the base of the sclerite ; terga

3-6 with narrow dorsal black lines widened suddenly near the apices

of the segments and occupying the caudal three-fourths ; seventh ter-

gum with a similar but broader dorsal line; caudal half of the dorsum
of the eighth, and all of the ninth and tenth black ; lateral margins of
all terga pale; sterna 3-7 black; one, two, eight, and ten pale; ovi-

positor pale, the lateral valves broad.



528

Measurements

Length, S 33-35 mm.
Length, 9 34 mm.
Length of abdomen, S 26 mm.
Length of abdomen, 9 26 mm.
Length of hind wings, S 19 mm.
Length of hind wings. 9 21 mm.
Width of hind wings, S 4 mm.
Width of hind wings, 9 4-4.5 mm.

This species is closely related to carunduatmn, chile, doiihlcdayi,

and cyathigcnim. The adult male is easily distinguished from those

species by means of the anal appendages; the female, less easily, by

means of the mesostigmal plates.

Illinois is within the range of the species and it probably occurs

within the state although there seems to be no record of its presence.

A large number of adults of both sexes have been examined, all

in the collection of Mr. E. B. WilHamson.

Enai^lagma carunculatum Morse

Nymph.—Color, green or buff.

Head about twice as broad as long, the caudo-lateral margins not

projecting strongly, but with a few strong setae ; antennae with the

third segment longest, the second longer than the first, the first two

and the proximal portion of the third darker than the rest ; mental setae

of the median lobe three, and sometimes a small fourth on each side

;

lateral setae six ; marginal setae of the median lobe eight or nine on

each side ; labium extending caudad between the first and second pair

of coxae.

Thorax : legs pale, the femora with very faint or no preapical

rings and distinct rows of m.oderately heavy setae ; tibiae and tarsi

with the usual apical scales and ventral setae ; metathoracic wing-cases

extending about to the middle of the fourth abdominal segment.

Abdomen with well-developed lateral keels, the keel of the first

segment with three or four setae; the second, with eight to twelve;

third, with about eleven; fourth, with thirteen to fifteen; fifth, eighteen

to twenty ; sixth, eighteen to twenty ; seventh, twelve to fourteen ; and

the eighth with about fourteen ; on the fifth and sixth keels the setae

are bunched at the apex, with sometimes as many as three together;

venter of the abdomen entirely without small setae on the cephalic seg-

ments, but usually with long hair-like setae on the dorsum of segments



529

two, three, and four. In mature nymphs there is an indefinite, dark

dorsal stripe extending from near the apex of the third segment to the

seventh or eighth; gills (Fig. 70) transparent, lanceolate, with a broad,

usually pale, opaque stripe along the axis from the base to near the tip;

dorsal marginal setae of the median gills usually more than twenty in

number and extending one-third the length of the gill from the base,

(he ventral setae of the same gill consisting of only a few setae and
extending half as far as the dorsal row; ventral marginal setae of the

lateral gills of similar extent to the dorsal setae of the median gill

;

apical margins usually without setae or hairs; ovipositor of the female

extending to the middle of the tenth abdominal segment and the lateral

valves with about four heavy setae on the ventral margin.

• Measurements

Length 13.5-14 mm.
Length of abdomen 8-9 mm.
Length of gills 5.5-6 mm.
Width of gills 1.2 mm.
Length of metathoiaeie wing-eascs. .3.6 mm.
Length of median lobe 2.5 mm.
Width of median lobe 5-2 mm.

Adult; Male-—Color, dark blue or buff and black.

Head blue or buff and black, the labium buff, the median lobe

subtriangular, the palpus moderately narrow ; antennae entirely black,

the first segment paler at the apex
;
postclypeus with a large, shining

black spot, the ventro-lateral margins pale; anteclypeus, and labrum
except a dorso-mesal black spot and a dorso-lateral spot on each side,

pale; exposed portions of the mandibles, their trochantins, the genae,

and a transverse stripe above the clypeus, pale; remainder of the front

and vertex dull black
;
postocular spots oval, buff or blue, and not

usually connected with the stripe caudad of the ocellar area; occiput

and postgenal regions pale except a black stripe caudo-ventrad of the

postocular spots.

Thorax blue or buff and black, the pronotum dull black with a

transverse median stripe on the cephalic lobe, the caudal margin of

the caudal lobe and small crescentic spots on the lateral margins of the

median lobe buff or blue ; dorsal third of the proepimera black, the

dorsal suture indistinct, the remainder of the sclerite buff or blue ; ceph-

alo-lateral angles of the mesostigmal plates elevated, the elevated por-

tion pale; pale stripe of the mesosupraepisternum regular, the margins
parallel and straight, the stripe extending from the cephalic margin



530

nearly t() the paraptera ; black stripe of the mesopleural suture widest

just caudad of the mesinfracpisternum, extending onto and covering

about the dorsal third of that sclerite, the stripe continuous at the

caudal extremity with a narrow stripe extending ventrad along the

caudal margin of the mesepimeron to the interpleural fold ; metapleural

suture with a black spot adjacent to the wing leases; remainder of the

thorax buff or blue ; legs striped, buff and black, the coxae and
trochanters usually pale, the femora with broad dorsal stripes from
bases to apices; tibiae with dorsal stripes covering about half the dorsal

surface and including the cephalo-ventral row of setae; tarsi and claws

pale, black at the tips, the claws very long; wings with nine to eleven

postnodal cross-veins and with M, arising near the fifth postnodal

cross-vein in the front wing and between four and five in the hind

wing.

Abdomen black and blue or buff; terga i-6, inclusive, blue or

buff, except a small black basal spot on one, a black apical ring and
dorsal spot occupying half the second and third terga. another covering

slightly more than half the fourth, two-thirds of the fifth and sixth,

and all of the seventh except the narrow lateral marginal stripes and
a basal ring; dorsum of the tenth tergum black; eighth and ninth terga

entirely blue or buff; sterna one and 3-8 with a median black line ; anal

appendages (Figs. 194, 205) short, the superiors usually black, blunt,

and with a narrow notch on the dorsum cephalad of but near the dorso-
caudal angle; inferiors paler, the black apices directed strongly dorsad

and frequently in contact witli the superiors.

Female.—Color similar to that of the male.

Head similar to that of the male ; the postocular spots are, how-
ever, considerably smaller.

Thorax similar to that of the male.

Abdomen with the dorsum of terga i— 10 with broad, dorsal dark
stripes, widened subapically on segments 2-4 inclusive, the pale color

occupying the larger part of the lateral surfaces of all terga as lateral

stripes which are continuous with the broad uninterrupted basal rings

on segments 4—7 and the interrupted ring of the third tergum; sterna

1-8 with a mesal black line from the bases to near the apices, the eighth

sternum with a long apical seta ; lateral valves of the ovipositor broad,

pale, the ventral margins serrate from apex nearly to base, the pro-

styles darker on the apical half.

Meaaurements

Length, $ 33 mm.
Length, 2 32 mm.



531

Length of abdomen, $ 26 mm.
Length of abdomen, 9 25 mm.
Length of hind wings, S 19 mm.
Length of hind wing.s, 9 19 mm.
Width of hind wings, S 4 mm.
Width of hind wings, 9 4 mm.

An inhabitant of the lake regions of IlHnois, the nymphs prefer-

ring iloating vegetation or rank growth along the banks of ponds or

lakes of considerable size, though they are occasionally to be en-

countered in the larger and clearer streams. •

The color of the recently emerged adult is buff or cream-color and

biack, and the blue is much slower in appearing than in other species.

Enallagma civile (Hagen)

Nymph.—Color, green or buff.

Head about twice as broad as long, the caudo-lateral angles not

projecting caudad or laterad, but armed with short setae; antennae

with the third segment longest, the first shorter than the second, the

first two segments and the proximal portion of the third dark brown,

the remainder of the third and the distal segments pale; labium ex-

tending just caudad of the first pair of coxae, the median lobe with

three or four mental setae, the labial palpi with five or six lateral setae

and a row of seven or eight small setae on the margin of the median

lobe.

Thorax pale buff or green ; legs very pale, the preapical femoral

rings indistinct, the femora with a dorsal and lateral row of setae and

scales near the tips; metathoracic wing-cases extending caudad to the

middle of the fourth abdominal segment.

Abdomen pale buff or green, frequently with an indefinite darker

stripe on the dorsum of segments 3-7, the cuticle sparsely provided

with minute setae, which are usually lacking on the venter of the

cephalic segments ; dorsum of two, three, and four with long hair-like

setae ; lateral keels well developed and setose, the first without setae,

the second with a row of about eleven, the third with twelve, the

fourth with sixteen, fifth with eighteen to twenty, sixth with fifteen to

sixteen, seventh with twelve to fourteen, and the eighth with a straight

row of about nine setae; gills (Fig. 75) lanceolate, colorless and
usually without pigment except in the smaller tracheae, the margins

very transparent ; dorsal marginal setae of the median gill extending

less than half the length of the gill from tlie base, and composed of

more than twenty setae ; ventral row of the lateral gills slightly longer



532

and about half the length of the gills; female ovipositor extending to

the middle of the tenth abdominal segment, the ventral margins of the

lateral valves setose, the row consisting of about eight stout setae and

a number of hair-like ones.

Measurements

Length 15 mm.
Length of abdomen 10 mm.
Length of gills 6 mm.
Width of gills 1.8-2.1 mm.
Length of metathoracic wing-cases. .4.5 mm.
Length of median lobe 3.1 mm.
Width of median lobe 8-2.3 mm.

Adult; Male.—Color, dark blue and black.

Head blue and black; mnuth-parts buff, the median lobe of the

labium suljtriangular, with a shallow, acute, median cleft, the labial

palpi much broader at the proximal end than at the apex; antennae

dark brown or black; postclypeus with a shining black spot on the

meson ; anteclypeus shining yellow ; labrum shining yellow with a black

dorso-mesal spot; exposed portions of the mandibles, trochantins, and

genae pale, and a pale stripe above the clypeus extending dorsad to the

level of the antennal fossae; remainder of the front and vertex dull

black
;
postocular spots oval or subcuneiform, the pale line caudad of

the ocellar area not distinct ; occiput and postgenae 3'ellow, except a

transverse black stripe caudo-ventrad of the postocular spots; com-
pound eyes dark brown or black.

Thorax blue and black, the black usually metallic
;
pronotum

black, the cephalic lobe with a pale transverse line, the median lobe

with a pale spot on the lateral margins and the caudal lobe also with

pale margins
;
proepimera with black doisal borders, pale below ; meso-

stigmal plates subcjuadrangular, the cephalo-lateral angles somewhat
elevated, though not as much so as in caninculatum, and the lateral

half covered by a yellow spot; dorsal black stripe regular and covering

nearly half of each supraepisternum ; pale stripe of the supraepi sterna

broadest dorsad of the mesinfraepisterna, extending nearly to the

paraptera; mesopleural black stripe of the suture narrowed cephalad

of the wing bases, broadest shortly caudad of the mesinfraepisterna

and extending across and covering about one-third of the latter; caudal

margin of the mesepimera black to the level of the interpleural suture;

metapleural suture with a black spot cephalad of the wing bases ; re-

mainder of the pleura blue, the postcoxal areas buff, becoming polli-

nose; paraptera black, the cephalic margins pale and a pale spot below

the lateral angles ; legs striped, the CLixae and trochanters pale, the



533

femora with stripes on the dorsum, the tibiae with black stripes occupy-

ing half the dorsa, but not reaching the apices of the segments; tarsi

and claws pale, dark at the tip, the claws notched at a considerable dis-

tance proximad of the tip ; wings with nine or ten postnodal cross-veins,

the vein Ma arising between the fourth and fifth postnodal cross-veins,

usually near the fifth, in the front wing, and between the fourth and

fifth in the hind wing.

Abdomen blue and black, the cephalic terga largely blue, the

caudal ones darker and frequently becoming pollinose with age ; terga

1-6, inclusive, blue except a small basal spot on the dorsum of one and

black shield-shaped apical spots and apical rings on 2-6; dorsal black

spot of the sixth tergum occupying about half the dorsum, those of

2-5 about one-fourth ; dorsum of the seventh and tenth terga black

except the lateral margins and a narrow, basal, interrupted ring on the

seventh ; all of the eighth and ninth terga blue ; sterna 2-10 with a black

median line; anal appendages (Figs. 198, 103) short, the superiors

blunt, with a narrow cleft or notch just ventrad of the apex ; inferiors

u.sually black and shorter, the black tips directed obliquely caudad and

dorsad and frequently in contact with the superiors.

Female.—Color similar to that of the male.

Head similar to that of the male.

Thorax similar to that of the male except in the color of the legs,

which are usually lighter, the dorsal stripes of the femora never ex-

tending to the proximal ends of those segments.

Abdomen : the dorsum of all terga have a black longitudinal stripe

from the bases to the apices and a short, narrow, apical, black ring;

margins of all terga yellow or blue, the pale color extending onto the

dorsum at the bases of segments 2-6, but always forming interrupted

rings and never connected across the dorsum (Fig. 92) as in cariin-

cnlatnm (Fig. 91) ; sterna 1-8 with a mesal line from bases to apices,

the apex of the eighth sternum with a heavy seta which is darker at

the tip than at the base; anal appendages of the usual form, the ovi-

positor with yellow lateral valves, the ventral margins of which are

serrate from the apex to near the base
;
prostyles brown, dark at the tip.

Measurements

Length, $ 29-32 mm.
Length, 2 30-32 mm.
Length of abdomen, $ 23-24 mm.
Length of abdomen, 9 23-24 mm.
Length of hind wings, $ 17 mm.
Length of hind wings, S 19-20 mm.
Width of hind wings, $ 3.5-4 mm.
Width of hind wings, 2 3.5-4 mm.



534

A common species at Urbana. It was not taken at Havana, where

carunculatum was abundant, nor at Lake Villa, where both caruncit-

latiiiii and Jiagcni were common. The females of these closely allied

species have been determined from material collected in the al)ove

localities. A study has also been made of specimens taken in Cf)pula.

in tlie collection of Mr. E. B. Williamson.

The imago emerges at Urbana as early as June 13 and apparently

continues to emerge throughout the season. Nymphs taken late in.

July emerged shortly after, and another lot, collected at Le.xington,

Ky., emerged as late as August 18, 1915. There is a possibility that,

the species has two broods a year.

Enallagma cyathicerum (Charpentier)

Nymph.—Color, buf?.

Head elliptical, the caudo-lateral angles rounded and sparsely

setose ; antennae of the usual form, the second segment slightly longer

than the first; labium broad, and extending caudad to the mesocoxae;

mental setae four, the proximal seta of both rows more than half as

long as the remaining ones ; lateral setae five or six ; marginal setae

of the median lobe four or five.

Thorax: femora without conspicuous rows of small setae; wing-

cases extending caudad to the middle of the third abdominal segment.

Abdomen with distinct lateral keels all of which are setose in-

cluding those of the first segment; the size of the setae gradually

increases caudad, and on each, lateral surface of the ninth segment

there is a row of setae in line with the lateral keels with two or

more setae grouped together at the caudal end of the row; gills (Fig.

71 ) clear and without cuticular pigmentation though reported by

Lucas ('00: 103) to have one or more narrow cross-bands beyond

the middle ; dorsal and lateral gills with closely placed marginal setae

which extend more than half-way from the bases to the apices of the

gills ; tracheal branches few in number and usually larger than are

found in civile or carunculainui; ovipositor of the female extending

caudad to the caudal margin of the tenth abdominal segment.

Measurements

Length ..14 mm.
Length of abdomen 9 mm.
Length of gills 5 mm.
Width of gills 1.5 mm.
Length of metathoracie wing-eases. . . .4 mm.
Length of median lobe 2.5 mm.
Width of median lobe 75-2 mm.



535

Described from three nymphal exuvia from France (Martin),

obtained from Mr. E. B. Williamson.

Adult; Male.—Color, pale blue and black.

Head black, blue, and buff; mouth-parts buff; median lobe sub-

triangular, the proximal segment of the labial palpi broad, the distal

segment pale; antennae dark, the second segment much longer than

the first; postclypeus black except the lateral margins and the ventral

margin, the anteclypeus, la1)rum, mandibles, and the transverse stripe

above the fronto-clypeal suture blue
;
genae, pale yellow ; remainder

of the front and vertex black
;
postocular spots large, blue, the margins

of the spots irregular and the spots narrowly separated from the

narrow stripe caudad of the ocellar area ; occiput, except a stripe

caudad of the postocular spots and the postgenae, pale blue.

Thorax : pronotum largely black, the cephalic lobe with the cephalic

half blue, median lobes with large oval blue spots; proepimera and
episterna blue with black dorsal borders ; mesostigmal plates narrow
and more than half pale ; dorsal carina with the black stripe which

covers it also covering one-half of each supraepisternum ; black stripe

of the mesopleural suture narrowed'considerably caudad and covering

ai)out one-third of the mesinfraepisterna ; remainder of the mesopleura,

except a small spot on the mesopleural suture near the wing bases,

pale blue; postcoxal areas yellowish blue; legs with blue coxae and
trochanters, the trochanters dark on the dorsum ; femora with a single

black stripe on each dorsum, the stripe ijroken by a small spot at the

base; cephalic half of the dorsum of the tibiae with black longitudinal

stripes; tarsi pale yellow, darker at the distal ends; wings with twelve

postnodal cross-veins in the front wing and ten in the hind ; stigma

surmounting less than a single cell, pale.

Abdomen blue and black; first tergum with small basal and
smaller lateral black spots; second tergum blue with a subelliptical

apical spot and an apical ring; terga three, four, and five with apical

spots connected with the apical rings; apical half of the sixth and
about four-fifths of the dorsum of the seventh with broad black stripes

expanded caudad but not reaching the margins of the terga ; terga

eight and nine pale; dorsum of ten black, the caudal margin distinctly-

incised on the meson, the lateral surfaces of the segment pale yellow;

first sternum pale, 3-8, inclusive, black; anal appendages (Figs. 201,

208) black and brown, the superiors short, bent ventrad and some-
what acute at the apex ; inferiors much longer than the superiors and
black at the tips.

Female.—Color in general similar to that of the male, the blue,

however, replaced by yellow.



536

Head and thorax similar to those of the male except that they

are somewhat lighter in color ; mesostigmal plates as shown in Figure

213.

Abdomen with broad longitudinal stripes on the second tergum
which are much expanded near the caudal margin ; terga 3-7 with

narrow longitudinal stripes, all of which are expanded near the caudal

margin, the longitudinal stripe of eight much reduced near the cephalic

margin (Fig. 93); anal appendages of the usual type; ovipositor

short, the lateral valves pale, ventral margins slightly serrate; pro-

styles short and blunt.

Measurements

Length, $ 31-32 mm.
Length, 9 31-32 mm.
Length of abdomen, S 24 mm.
Length of abdomen, $ 26 mm.
Length of hind wings, S 19-21 mm.
Length of hind wings, 9 20 mm.
Width of hind wings, 3 4 mm.
Width of hind wings, 9 4 mm.

This species is most closely related to calvcrti, from which the

female differs in having more black on the dorsum of the eighth

tergum and in the characters of the mesostigmal plates. The male

may be distinguished by means of the anal appendages.

Described from a number of both sexes in the collection of Mr.

E. B. Williamson. The species has not been reported from Illinois,

but probably occurs here.

Enallagma divagans Selys

Nymph.—Unknown.
Adult; Male.—Color, blue and black.

Head blue and black ; labium pale, median lobe subtriangular, the

labial palpi including the distal segment pale, the proximal segment

narrow; antennae dark, the first two segments subequal, the first

pale at the tip; postclypeus black, anteclypeus except a small dorso-

mesal black spot, the mandibles, their trochantins, genae, and a trans-

verse area above the fronto-clypeal suture pale blue; remainder of

the front black; vertex with pale subcuneiform postocular spots,

the remainder of the dorsal portion black ; occiput and postgenae pale

blue or buff with the exception of a large black spot laterad of the

occipital foramen on each side.



537

Thorax blue and black
;
pronotum black, cephalic lobe largely blue,

the median lobes with large spots adjacent to the proepimera, and the
caudal lobe with small spots on the lateral angles and one on the meson

;

proepimera distinct blue and with a dorsal, crescentic, black spot;

mesostigmal plates largely blue, the mesal angles black; mesosupra-
episterna black, with blue longitudinal stripes from the cephalic mar-
gins to the wing bases, the stripe slightly widened cephalad, narrowed
at the middle, and widened again caudad ; mesopleural suture covered
by a black stripe which occupies a portion of the supraepisterna and
the epimera, being widest about the middle, narrowed near the wing
bases, extending cephalad across the infraepisterna and covering about
one half of those sclerites; remainder of the pleura blue, with the ex-

ception of spots on the interpleural fold and metapleural suture ad-

jacent to the wing bases ; legs buff or pale blue and black ; coxae blue

with a black basal spot on the cephalic surfaces; dorsum of the

trochanters dark, remainder pale; femora with slight dorsal carina,

the dorsal longitudinal stripes usually covering the carinae, but the

stripes sometimes divided by a paJe line on the carina, and emarginate
at the proximal end ; tibiae mostly pale with faint cephalo-dorsal

stripes or row of dashes, the ventral surfaces with black spots at the

base and apex ; tarsi pale, the segments darker at the distal end ; wings
with twelve postnodal cross-veins in the front wing and ten in the

hind wing ; stigma pale, surmounting less than a single cell ; M^ arising

near the fifth postnodal cross-vein in the front wing and between three

and four in the hind wing.

Abdomen blue and black with a touch of bronze; first and second
terga blue, with black, dorsal, longitudinal stripes, the first with a very
narrow subapical ring of black which does not reach the lateral

margins; longitudinal stripe of the second tergum expanded subapically

and the tergum with a broader apical ring extending from the meson
half-way to the lateral margins; terga 3-7 with dorsal longitudinal

stripes which are contracted to the meson near the cephalic margin,
but widen subapically and unite with the black apical rings; terga
eight and nine entirely blue; dorsum of the tenth tergum entirely

black, the venter pale blue or buff; anal appendages (Fig. 190) short,

black, the superiors bilobed, the dorsal arm knob-like, the ventral

lobe more slender ; inferiors slender, directed obliquely dorsad and
frequently in contact with the ventral arm of the superiors; first

sternum pale, 3-9 black.



5S8

Female.—Color similar to that of the male.

Head similar to that of the male.

Thorax: hlack stripe of the mesoplciiral suture divided by a line

of brown ; mesostigmal plates as shown in Figure 224.

Abdomen: terga 1—7, inclusive, similar to corresponding terga

of the male, the lateral blue stripes of the margin becoming dull

brown on the apical segments; eighth tergum black, with pale blue

lateral spots on the caudal margin; tergum nine blue, with two short

dorso-lateral black stripes which fuse at the base of the meson

;

tergum ten blue; anal appendages dark brow'n, ovipositor pale bufif,

the prostyles short and blunt.

Measurements

Length, S 29-33 mm.
Length, 9 32 mm.
Length of abdomen, S 24-28 mm.
Length of abdomen, 5 26 mm.
Length of hind wings, S 17-18 mm.
Length of hind wings, 9 18 mm.
Width of hind wings, $ 3.5 mm.
Width of hind wings, 2 3.5 mm.

This species is very closely related to c.vsulans, the male differing

principally in the possession of blue on the eighth tergum and in the

character of the anal appendages. The female can not be separated

from c.rsiilans except by the mesostigmal plates. It is, however, a

much more slender and delicate insect.

Described from eighteen males and one female in the collection of

Mr. E. B. Williamson.

A rare species, reported from Ohio, but not yet taken in Illinois

by collectors.

Enallagma doubIvEdayi Selys

Nymph.—Unknown.
Adult; Male.—Color, light blue and black.

Head blue and yellowish and black; antennae uniform brown,

the second segment slightly longer than the first ; anteclypeus and
labrum shining yellow; exposed portions of the mandibles, their

trochantins, genae, and the front dorsad of the clypeus to the level of

the antennal fossae pale ; remainder of the front black
;
postocular spots

small, the narrow stripe caudad of the ocelli distinct ; occiput and post-

genae pale ; compound eyes dark brown.



539

Thorax black, blue, and yellowish green
;
pronotum black, the

cephalic lobe, a small spot on each median lobe, and the caudal margin

of the caudal lobe pale; proepimera and episterna pale, the noto-

epimeral suture indistinct
;
paraptera black ; mesothorax with a broad

black dorsal stripe, the stripe covering about one-third of the meso-

supraepisterna on each side ; remainder of the thorax, including the

postcoxal areas, buff with the exception of small dark spots on the

metapleural sutures near the wing bases ; legs black and yellow, the

coxae and trochanters pale, darker on the cephalic surfaces; femora

each with a broad black dorsal stripe which frequently includes one

row of setae ; tibiae with longitudinal stripes on the cephalic surfaces

;

wings with about ten postnodal cross-veins in the front wing and eight

in the hind one; RL arising between the fifth and sixth postnodal

cross-veins in the front wing and between the fourth and fifth in the

hind wing.

Abdomen blue and black; terga i-io blue except a small basal

spot on the first, a hastate spot on the second, an apical spot and
marginal ring on the second to the fifth, the apical half or two-fifths

of the dorsum of the sixth, dorsum of the seventh (excepting a narrow
interrupted basal ring), and the tenth, which are pale; anal appendages

(Figs. 169,175) similar to those of carunculatnm and civile, but the

superiors differ (compare Fig. 169 with Figs. 176 and 179) in having

a smaller pale tubercle at the end and in being much wider proximad
of the tubercle.

female-—Color, similar to that of the male.

Head similar to that of the male.

Thorax: mesostigmal plates (Fig. 226) similar to those of civile,

but the caudal margins concave, instead of convex as in the latter.

Abdomen : terga i— 10 with broad dorsal dark stripes and basal in-

terrupted rings, the lateral margins pale; anal appendages of the usual

type and the ovipositor pale, the ventral margins of the lateral valves

serrate.

Measurements

Length, 5 31 mm.
Length, $ 31 mm.
Length of abdomen, S 25 mm.
Length of abdomen, 2 24 mm.
Length of hind wings, $ 17 mm.
Length of hind wing.s, 9 18 mm.



540

Described from a number of specimens in the collection of E. R .

Williamson.

This species has not been reported from Illinois. It has been

collected in Ohio and was originally described from Florida. It is

possible that it may occur occasionally in southern Illinois.

Enali,agma ebrium (Hagen)

Nymph.—Not available for study.

Adult; Male.—Color, blue and black.

Head black and blue ; moutli-parts pale, the labium with a sub-

triangular median lobe; labial palpi buff, the distal segment dark at

the apex ; antennae black except the tips of the first and second seg-

ments
;
postclypeus black ; anteclypeus, labrum, exposed portions of

the mandibles, their trochantins, genae, and a transverse stripe above
the clypeus, pale ; remainder of the front and vertex black

; postocular

spots large, subcuneiform, the margins irregular; occiput and post-

genae pale except a transverse black stripe caudo-ventrad of the post-

ocular spots.

Thorax blue and black
;
pronotum black, the cephalic lobe with a

pale transverse stripe, median lobes with pale spots on the lateral and
caudal margins of the caudal lobe; dorsal border of the proepimera
black, the ventral two-thirds pale ; mesostigmal plates elongate, the

lateral angles covered with a pale spot and slightly elevated, though
not as much as in caniiiciilafnm or cizilc; dorsal mesothoracic stripe

occupying about one-third of each supraepisternum, the lateral margins
parallel ; pale stripe of the supraepisterna extending from the cephalic

margin to near the jiaraptera, widest aljove the infraepisternum ; black

stripe of the mesopleural suture widest just caudad of the infraepi-

sternum, and extending across and occupying about one-half of that

sclerite; caudal margin of the metepisterna black and a black spot on
tile metapleural sutures cephalad of the wing bases; remainder of the

pleura blue, the postcoxal areas buff; paraptera l)lack, trapezoidal,

the cephalic margins and a spot just below tlie lateral angles pale;

legs striped, black and buff, the femora and coxae pale, the entire

dorsum of the femora black except a small spot near the base, fre-

quently appearing as an emargination of the black dorsal stripe; tibiae

with a black stripe from base to near the apex, occupying half or less

of the dorsal aspect and often including the cephalo-ventral row of

setae ; tarsi and claws pale, dark at the tips ; wings with nine to ten

postnodal cross-veins in the front wing; vein RL, arising between the



541

fourth and fifth postnodal cross-veins in the front wing and between
three and four in the hind wing.

Abdomen bkie and black ; terga largely blue, with black spots on
the base of the first and the apices of 2-6 inclusive, all of the dorsum
of seven blue except a basal interrupted ring, and all of ten blue;

terga eight and nine blue; sterna 3—8 with mesal lines of black from
the cephalic to near the caudal margins; anal appendages (Figs. 189,

196) short, pale, the superiors bifid, the two arms equal in length;

dorsal arm of the superior appendages black at the tip and forming
a blunt hook ; ventral arm pale and nearly straight ; inferior appendages
pale, dark at the tips and about as long as the superiors.

Female.—Color, black and yellow or blue.

Head similar to that of the male, the blue, however, sometimes

replaced by yellow.

Thorax similar to that of the male ; mesostigmal plates as shown
in Figure 227.

Abdomen with broad dorsal stripes on segments 2-10, the stripes

contracted to the meson on the bases of terga 3-7 inclusive, and
widened subapically on segments 2—y. the widened portion not reach-

ing the lateral margins ; first tergum pale, with a black spot at the

base; sterna 1—8 with black median stripes; ovipositor of the usual

form and not reaching caudad of the tenth segment, the ventral mar-
gins of the lateral valves feebly serrate.

Measurements

Length, $ 29 mm.
Length, 9 29 mm.
Length of abdomen, $ 23-25 mm.
Length of abdomen, 9 24 mm.
Length of hind wings, $ 16-17 mm.
Length of hind wings, 9 18 mm.
Width of hind wings, $ 4 mm.
Width of hind wings, 9 4 mm.

'

The anal appendages of the male distinguish the species from
closely allied members of the genus, and the mesostigmal plates of the

females are also characteristic.

Described from a number of males from Illinois in the collection

of the State Laboratory of Natural History, and from females in the

collection of E. B. Williamson.



542

ExALCAGMA EXSULANS (Hagen)

Nyiiipli.—Color, dark brown or greenish.

Head slightly broader than long, the caudo-lateral angles pro-

jecting caudad and provided with heavy setae; second antennal seg-

ment shorter than the first, the first two darker than the remaining

ones and pilose; labium extending just caudad of the procoxae, mental

setae three in numlier; lateral setae four or five, and six or seven

marginal setae on the median lobe.

Thorax : legs with a few hair-like setae, the femora each with a

preapical ring of brown and the tibiae with the usual scales at the tip

;

apices of the third tarsal segments and the apices of the claws dark;

metathoracic wing-cases extending caudad to the fourth abdominal

segment.

Abdomen slender, the cuticle proxided with minute setae and
minute brown spots ; lateral keels well developed on segments i-8,

the keels on segments 4-8 and the lateral apex of segment nine with

small groups of two to five setae; gills (Figs. 53, yy, yys.) broadly

lanceolate, broadest beyond the middle, usually heavily pigmented on
the proximal two-thirds, the area of infuscation being followed by.

two large clear spots on each side of the axis, the distal end of the

gill being dark, the extreme tip white; marginal setae of the median
gill consisting of a dorsal row extending from the base to the light

spots, or nearly two-thirds the length of the gills, and ventral marginal

setae of the lateral gills of similar extent ; apical margins of all gills

hairy; smaller tracheae forming alga-like patches; ovipositor extend-

ing to the middle of the tenth abdominal segment.

Measurements

Length 12-13.5 mm.
Length of abdomen 9-10 mm.
Length of gills 5.5-7 mm.
Width of gills 1.8-2 mm.
Length of median lo])e 2 mm.
Width of median lobe 6-1.8 mm.

Adult; Male.—Color, pale blue, black, and brown.

Head pale blue and black; median lobe of the labium buff, sub-

triangular, the cleft obtuse at the base; antennae entirely black; post-

clypeus black, shining, the anteclypeus pale and the labrum with a

transverse black stripe on the dorsal margin ; exposed portions of the

mandibles, their trochantins, genae, and a transverse area between



543

the compound eyes and above the clypeus, pale blue ; remainder of the

front, and the vertex, black
;
postocular spots and the postgenae and

occiput yellow.

Thorax blue and black
;
pronotum largely black, the cephalic lobe

blue; large spots on each mesal lobe and a smaller one on each, near

the meson, blue, and a blue triangular mesal spot on the caudal lobe;

proepimera largely blue, the dorsal sutures indistinct and covered with

black; mesostigmal plates elongate, tlie lateral angles covered by a
blue spot; dorsal carina with a broad, black stripe, which covers also

about one-half of the mesfJSupraejMsterna on each side ; the dorsal stripe

is followed on each supraepisternum by a narrower blue stripe extend-

ing from the cephalic margin caudad to near the paraptera, the stripe

being narrowed at both ends; the black stripe of the mesopleural

suture is broad, extends ventrad well onto the metepimera, and in

younger specimens is divided by a brown line which is directly over

the suture ; dorsal third of the mesinfraepisterna, and spots on the

metapleural sutures near the wing bases, dark brown or black ; re-

mainder of the pleura blue, postcoxal areas brownish or buff; legs

pale blue, or brown and black, the coxae and trochanters pale, the

femora each with a faint dorsal carina on one side of which is an indefi-

nite line and on the other a row of spots, the hind femora, however,
often entirely pale ; tarsi and claws pale, dark at the tips ; wings with ten

to eleven postnodal cross-veins and M^ arising between the fourth and
fifth postnodal cross-veins in the front wings and between three and
four in the hind wing.

Abdomen blue and black, the dorsum of terga 1-9 and ten with
longitudinal black stripes from base to apex, widened subapically on
segments 2-7 and narrowed to the meson on the apex of the eighth

tergum ; lateral surfaces of terga 1-8 and ten, all of nine, narrow
apical ring on one, narrow basal ring on three, and a broad basal

ring on four, five, and six, blue or pale ; anal appendages ( Figs. 203,
210) black, the superiors bifurcate, the dorsal arms shortest and with
minute points directed niesad ; inferiors paler and shorter than the

superiors.

Female.—Color, pale green (pale viridine green), black, and
brown, tip of the abdomen bhie.

Head similar to that of the male except that the postocular spots

are connected with the narrow stripe caudad of the ocelli, and the

genae and stripe above the clypeus are usually more or less orange in

color.



544

Thorax with the brown of the mesopleural dark stripe covering'

the suture more conspicuous and persistent than it is in the male;

mesostigmal plates as shown in Figure 220.

Abdomen with broad dorsal stripes on segments 1-8, the stripe

on nine being reduced to two triangular spots at the base of the tergum,

the remainder being blue in color ; tergum ten blue ; lateral surfaces of

terga 2-8 and narrow interrupted basal rings on segments 3-8 pale

green ; sterna 2-8 with black mesal lines, the eighth with a long apical

seta; ovipositor and anal appendages of the usual form, the lateral

valves of the ovipositor blue or pale and serrate on the ventral margins

;

prostyles dark brown.

Measurements

Length, S 35 mm.
Length, 9 32 mm.
Length of abdomen, S 29 mm.
Length of abdomen, $ 26 mm.
Length of hind wings, S 19 mm.
Length of hind wings, 9 20 mm.
Width of hind wings, $ 4 mm.
Width of hind wings, $ 5 mm.

One of the most common and wide-spread species of the state.

The nymphs prefer meadow brooks, but also inhabit small lakes and

ponds. In numbers this species is equal to signatmn. The adults

emerge early and fly throughout the summer.
Specimens have been seen from Dubois, Carbondale, Carmi,

Golconda, Lake Villa, Oregon, and Cook County.

ENAttAGMA GEMINATUM KelHcott

Nymph.—Color, usually green.

Head about three times as broad as long, elliptical, the caudo-

lateral angles not projecting caudad or laterad, evenly rounded, and

possessing only a few setae; third segment of the antennae longest

and the second segment decidedly longer than the first ; segments 1-3 or

1-4, dark in color ; labium extending slightly caudad of the procoxae

;

median lobe with three mental setae and sometimes a minute fourth

;

lateral setae five; median process of the labial palpi with only two

teeth; lateral margins of the median lobe with three or four small

setae caudad of the articulations of the labial palpi.

Thorax : legs without dark rings near the apex or with very faint

ones, the femora provided with rather long setae ; tarsal claws dark at



545

the tips; metathoracic wing-cases extending to the caudal margin of

the fourth abdominal segment.

Abdomen with moderately well-developed lateral keels on seg-

ments one to eight inclusive, the first without setae, the second with a

bunch of three or four, the third with an irregular double row, and
tlie fourth to the eighth possessing irregular single rows, with some-
times two setae at the apices ; segment nine, although possessing no
keel, has an irregular double row of setae in line with the keels of the

preceding segments; gills spatulate to lanceolate (Fig. 72), without

pigment except in the smaller tracheae and sometimes a trace along
tlie axis; dorsal marginal row of setae of the median gill extending
much less than half the length of the gill and containing seventeen or

eighteen setae, the ventral row of the same gill short and composed of

only a few setae ; ventral marginal row of the lateral gills also less than
one-half the length of the gills; the black tracheae of the gills dififer

greatly from those of other clear-gilled species in being fewer in num-
ber and branching from the axis more nearly at right angles ; oviposi-

tor extending caudad to the apex of the tenth abdominal segment.

Measurements
)

Length 11-12 mm. ^

Length of abdomen 9 mm. •

Length of gills 4.7 mm. '

Width of gills 1.3 mm.
Length of metathoracic wing-cases ... 2 mm.
Length of median lobe 2 mm.
Width of median lobe 6-1.5 mm.

Adult; Male.—Color, pale blue (pale methyl-blue), black, and
buff.

Head blue and black, the mouth-parts buff, with a tinge of blue ;

median lobe of the labium subtriangular, the cleft shallow and rounded
at the proximal end; labial palpi with slender distal segments, pale,

and not darker at the tip ; antennae dark brown or black, the tips of the

first and second segments sometimes pale; postclypeus shining black

except the latero-ventral angles, which are blue; anteclypeus and
labrum except a small dorso-mesal black spot, blue ; exposed portions

of the mandibles, their trochantins, genae, and a transverse area dorsad
of the clypeus blue; remainder of the front black; postocular spots

large, blue, rather irregular and frequently serrate on the margins;
pale stripe caudad of the ocelli wanting; occiput and postgenae buff.



546

except a transverse stripe caudad of each postfKular spot ; compound
eyes dark Ijfovvn above, the brown area inchuliiig a crescent-shaped

paler stripe, the eyes pale yellow Iielow.

Thorax blue and black, buff below
;
pronotum black, the narrow

cephalic lobe and the caudal lobe largely blue, the median lobes entirely

black; proepimera largely blue; mesostigmal plates narrow, the lateral

angles and the caudal margin with a broad i)lue stripe ; black stripe

of the dorsal carina covering one-third to one-half of each mesosupra-

epistcrnum; supraepisternal blue stripe somewhat irregular, not reach-

ing tlic caudal margin of the sclerite, contracted at the caudal third

or fourth, and occasionally interrupted, forming an exclamation point

;

mesopleural black stripe of the suture widest adjacent to the infra-

episternum and covering the dorsal thirtl of tliat sclerite; at the cautlal

extremity the stripe extends ventrad along the caudal margin of the

mesepimera to the interpleural fold ; metapleural suture with a black

line; remainder of the pleura, including the ventral half of the mes-

epimera, all of the metepisterna. and the epimera, blue
;
postcoxal

areas pale or buff; legs striped, black and blue or buff, the coxae and

the trochanters mostly pale, the coxae sometimes with dark spots;

femora each with a broad dorsal stripe from base to the apex and
tiie tibiae with a brown or black stripe occupying half the dorsum and
frequently including the cephalo-ventral row of setae; tarsi and claws

black, the claws deeply bifid at the tip ; wings with seven to nine post-

nodal cross-veins and with Mj arising between the fourth and fifth

pcstnodal veins in the front wing and between three and four in the

hind wing.

Abdomen blue, buff, and black ; first tergum blue, a black liasal

spot occupying half the dorsum, and the caudo-lateral margin black

;

second tergum blue except a subapical dorsal spot, an apical ring,

and a longitudinal stripe near the lateral margin, which are black;

segments 3—7 with longitudinal black stripes on the dorsum from
near the bases to the apices, the stripes widened subapically, connecting

with the apical rings and extending to the lateral margin of the terga;

entire dorsum of tergum ten and a narrow lateral marginal stripe from
bases to apices of terga eight and nine black or dark brown, the

whole of the dorsum of the eighth and nintli terga pale blue ; lateral

margins and basal rings of terga 3—6 pale yellow or blue, the lighter

color connecting across the dorsum on the bases of the third and

fourth terga and extending onto the dorsum but interrupted on the

meson in terga 5-7; anal appendages (Figs. 204, 211) black and buff',

the superiors black, with paler tips, and curved ventrad and caudad;



547

inferiors slightly longer than the superiors, yellowish buff with black

tips, the tips directed mesad.

Female.—Color, similar to that of the male.

Head similar to that of the male except that the dorsal half or

third of the labrum is usually brown.

Thorax similar in all respects to that of the male; mesostigmal

plates as shown in Figure 216.

Abdomen with broader dorsal stripes on terga 2-7, all of which

extend to the bases of the segments; terga nine and ten entirely brown

except the pale lateral margins ; tergum seven brown, with large blue

spots occupying the larger portion of the sclerite and separated from

one another only by a mesal line of black; dorso-apical margin of

seven and eight blue; sterna 2-8 with a black mesal line, the eighth

with a long apical seta; anal appendages of the usual type, the lateral

valves of the ovipositor broad and serrate on the ventral margins;

prostyles dark brown, short.

Measurements

Length, $ 26-27 mm.
Length, 9 26-27 mm.
Length of abdomen, $ 21 mm.
Length of abdomen, 9 21 mm.
Length of hind wings, $ 15 mm.
Length of hind wings, 9 16 mm.
Width of hind wings, $ 3.5 mm.
Width of hind wings, 9 4 mm.

This species is characteristic of the smaller lakes and larger

ponds, the nymphs inhabiting floating vegetation, and the adults flying

near the surface of the water close to the habitat of the nymphs. The
nymphs do not live in meadow brooks or swift streams.

Both nymphs and adults were taken at Havana, Illinois, and at

Lake \"illa during the latter part of June and the first of July.

Enallagma hageni (Walsh)

Nymph.—Color, buff or greenish.

Head subelliptical, the caudo-lateral angles projecting slightly

caudad and armed with a few heavy setae; antennae with the third

segment longest, the second longer than the first ; labium, when folded,

extending caudad to the second pair of coxae, the mental setae of the

median lobe three, the lateral setae usually five, and the marginal

setae of the median lobe usually three or four.



548

Thorax nearly uniform in diameter throughout, the prothorax

somewhat smaller ; legs with faint preapical femoral rings of brown,

and the usual apical scales present on the tibiae ; tarsi and claws pale

;

metathoracic wing-cases extending to the middle of the fourth ab-

dominal segment.

Abdomen slender, and with a row of spots on the cephalo-lateral

angles of the terga and sterna of segments 2—9; lateral keels strongly

developed, setose, the first keel usually without setae, the second,

third, and fourth with a bunch of four or five at the apices, the fifth

with about five apical setae and a weaker row extending to the base

of the segment ; sixth, seventh, and eighth keels with six setae at the

apices and a proximal row of about nine setae on each ; segment nine

without lateral keel, but with a row of setae along tlie line of the lateral

keels, composed of two heavy setae near the caudal margin and a

straight row of six smaller setae extending cephalad to the margin
of the segment; cuticle of the abdomen without dark spots at the

bases of the minute setae which cover the surface ; dorsum of seg-

ments two and three and the base of four with long hairs; gills (Fig.

76) lanceolate, almost colorless, widest beyond the middle and rather

obtusely pointed; tracheae pigmented in certain areas which form
about twelve alga-like patches around the margins of the gills; dorsal

marginal setae of the median gill extending half-way from the base

to the tip and composed of more than twenty setae ; ventral setae of

the lateral gills extending more than half-way from the base to the

tips of the gills; apical margins of all gills with a few scattered hairs.

Measurements

Length 14-15 mm.
Length of abdomen 9 mm.
Length of gills 5 mm.
Width of gills 1.8 mm.
Length of metathoracic wing-cases. .3.6 mm.
Length of median lobe 2 mm.
Width of median lobe 7-1 mm.

Several specimens obtained from Dr. E. M. Walker have been

studied. Specimens of this species are also present in the collection of

the Illinois State Laboratory of Natural History and have been iden-

tified by comparison.

Adult; Male.—Color, pale blue and black.

Head black and yellowish, the mouth-parts bufif, the median lobe

of the labium subtriangular ; antennae black or very dark brown;



549

postclypeus largely black, the anteclypeus and the labrum shining

yellow; exposed portions of the mandibles, their trochantins, genae,

and a transverse stripe dorsad of the clypeus yellow; remainder of

the front black; the oval postocular spots and the narrow transverse

stripe caudad of the ocelli green; occiput and postgenae pale; com-
pound eyes dark brown.

Thorax black, blue, and yellowish green
;
pronotum dull black,

the cephalic lobe, a small spot near the lateral margin of each median
lobe, and the caudal margin of the caudal lobe yellowish green; pro-

epimera pale, the noto-epimeral sutures indistinct ; mesostigmal plates

with a pale lateral spot; paraptera black; mesothorax with the usual
dorsal stripe, a broad pale stripe on each supraepisternum, and a black

stripe covering the mesopleural suture, extending over the infraepi-

sternum, and covering about one-third of that sclerite; remainder of
the thorax, including the postcoxal areas, yellowish green or blue with
the exception of a small dark spot on the metapleural suture just

cephalad of the wing bases; legs black and yellow, the coxae and
trochanters pale, the femora each with a broad black dorsal stripe

from base to apex, and the tibiae with a similar stripe on the cephalic

surfaces, which frequently includes one of the rows of setae; tarsi

and claws brown, black at the apices ; wings with ten postnodal cross-

veins in the front wing and about eight in the hind one; M2 arising

between the fourth and fifth postnodal cross-veins in the front wing
and between the third and fourth in the hind wing.

Abdomen blue and black; terga i-io blue except a small black

basal spot on the first, an apical spot and marginal ring on the second
to the fifth, the apical half or two fifths of the dorsum of the sixth,

the dorsum of the seventh except a narrow interrupted basal ring,

and the dorsum of the tenth, which are black; anal appendages (Figs.

161,162) short, the inferiors subcorneal, the superiors slightly shorter,

broad and flat, subquadrangular when seen from above, pointed, and
similar in appearance to the inferiors when seen in lateral profile.

Female.—Color, yellowish green and black.

Head similar to that of the male.

Thorax also like that of the male; the mesostigmal plates (Fig.

221) are characteristic, being short and broad and having the caudo-
lateral angles distinctly elevated ; the blue of the male thorax is usually
replaced by a yellowish green.

Abdomen black and yellow; terga i-io black except the lateral

surfaces and an apical ring on the first, lateral surfaces of 2-10, and
interrupted basal rings on 3-6 inclusive, which are pale blue or green-



550

ish ; anal appendages of tlie usual type ; the lateral valves of the ovi-
'

positor are pale yellow, the prostyles light brown ; apex of the eighth

sternum with a long seta.

Measurements

Length, $ 30 mm.
Length, 9 30 mm.
Length of abdomen, $ 23-24 mm.
Length of abdomen, 9 23-24 mm.
Length of hind wings, S 17 mm.
Length of hind wings, 9 17 mm.
Width of hind wings, S 3.5 mm.
Width of hind wings, 5 4 mm.

A common species in the lake region of Illinois, hut not observed

as far south as Urbana. The adult female is closely related to caniiicii-

latiim and cknlc, from which it may be separated by means of the

wing venation, the vein Mj usually arising between the third and
fourth postnodal cross-veins, by the narrower pale abdominal rings at

the bases of the terga, and by the character of the mesostigmal plates.

The males are easily separated from caniiiciilatuiii and ciz'ilc by means
of the anal appendages.

Enallagma pollutum (Hagen)

Nymph.—Color, pale green or buff.

Head elliptical, about twice as broad as long, the caudo-lateral

angles slightly projecting and furnished with but few setae ; antennae

of the usual form as regards length of the segments, the first two
segments, however, being much thicker than the distal ones and the

second usually shorter than the first; first antennal segment dark in

color, the remaining ones paler; labium extending slightly caudad of

the first pair of coxae, with three mental setae ; five lateral setae and
three or four marginal setae on the median lobe.

Thorax about twice as long as broad; legs light in color, with

a few scattered setae, the femora with preapical rings of brown, the

tibiae sometimes with a dorsal row of black dashes ; metathoracic

wing-cases reaching the middle of the third abdominal segment.

Abdomen slender, the lateral keels strongly developed and setose,

the setae being grouped conspicuously near the apices of the keels,

especially on segments 2-6; dorsa of segments 4-10 with apical trans-

verse rows of small setae, the row on the tenth interrupted on the

line of the meson, and those on 2-5 irregular, and consisting of several



551

rows together ; ovipositor extending to the middle of the tenth ab-

dominal segment, the ventral margins of the lateral valves with a

sir.gle row of setae; venter of the abdomen without the median black

stripe of signatum, but with a double row of black spots near the

apical margins, two on each of segments one to six and sometimes
on seven also; gills (Fig. 57) lanceolate, freciuently much and suddenly

widened beyond the middle, conspicuously banded, usually with two
darker cross-bands (more or less fused) near the proximal third

and three lighter crescentic ones which are sometimes wanting, axis

dark, the median gill without dorsal marginal setae, the ventral margins

of the lateral gills with a thick row extending slightly more than

one-third the length of the gills from their bases, or extending from
the base to the point where the first dark cross-band reaches the margin.

Mcasuremenis

Length 15.5 mm.
Length of abdomen 9 mm.
Length of gills 5.5 mm.
Length of metathoraeie wing-eases. . .4.1 mm.
Length of median lobe 1.8 mm.
Width of median lobe 5-1.5 mm.

Adult; Male.—Color, lemon-yellow (strontian yellow) or very

pale blue, and black ; the majority of specimens are yellow, the blue

tenerals being infrequent.

Head yellow and black ; labium pale yellow, median lobe subtri-

angular; antennae brown and pale, the first segment and basal two-
thirds of the second pale, the remainder dark brown; postclypeus

with a large black spot occupying almost the whole of it and within

which are two small yellow spots; anteclypeus and labrum yellow

except a median, dorsal, brown spot on the labrum ; exposed portions

of the mandibles, trochantins, genae, and a transverse area above
the clypeus extending dorsad to the level of the median ocellus, yellow;

remainder of the front black except a small transverse stripe

cephalad of the median ocellus and small spots cephalo-ventrad of
the lateral ocelli; postocular spots large, cuneiform, connected with
the narrow stripe caudad of the ocellar area ; the black of the vertex

extends along the margin of the compound eyes a short distance

caudad and ventrad of the postocular spots and sends mesad a broad,

short band ; remainder of the occiput and postgenae pale yellow.

Thorax yellow and black
;
pronotum yellow and black, the broad

cephalic lobe mostly yellow, the median lobes each with a large yellow



552

spot and a smaller one mesad of it; caudal lobe with a yellow caudal

margin; proepimera yellow, with very little black or brown; mesostig-

mal plates subtriangular, yellow, with a small brown spot near the mesal

margin, the caudo-mesal angles slightly elevated, dorsal carina covered

by a broad black stripe, the lateral margins of which fade into brown;
black stripe of the mesopleural suture reduced to an indefinite pale

brownish area near the middle of the horizontal portion of the suture

;

black spots adjacent to the dorsal margin of the mesinfraepisterna

and small spots just cephalad of the wing bases; dorsal third of the

mesinfraepisterna marked with small, crescentic, black spots; meta-

pleural sutures with small black spots just cephalad of the wing bases;

remainder of the mesopleura yellow; paraptera black with yellow

cephalic margins and pale spots ventrad of the lateral angles; legs

mostly yellow, the coxae and trochanters pale, the femora with a

faint dorsal line, the tibiae with a faint indefinite dorsal line or row
of dashes, and the tarsi and claws tipped with brown; wings with

nine to eleven postnodal cross-veins and with Mo arising between the

fourth and fifth postnodal veins in the front wing and between three

and four in the hind wing.

Abdomen yellow and black, the dorsum of terga i-8, inclusive,

with black longitudinal stripes from near the base to the apex of

each; lateral stripes on terga 1-7, narrow basal rings on 3-7, and a

very narrow apical ring on the first tergum, yellow; all of the ninth

and tenth terga blue except a narrow mesal line on the tenth; sterna

3-8 with a mesal line of black; anal appendages (Figs. 186, 193)
brown, the superiors much longer than the inferiors, broad at the

apices, and with the caudo-dorsal and caudo-ventral angles folded

mesad; inferiors small and yellow, the black apices directed mesad.
Female.—Color, lemon-yellow or very pale blue, and black.

Head similar to that of the male.

Thorax of slightly paler tint than in the male ; mesostigmal plates

(Fig. 225) with a large lateral black spot, the lateral margins rounded,

and the plates contiguous with the mesinfraepisterna.

Abdomen yellow and black, the terga similar to those of the

male with the exception of nine and ten, which are usually yellow,

the ninth having a triangular black spot at the base; sterna 2—8 with

a mesal line of black, the eighth with a long seta at the apex; lateral

valves of ovipositor yellowish, serrate on the ventral margins, the

prostyles brown.

Measurements

Length, $ 34 mm.
Length, $ 34 mm.



553

Length of abdomen, S 28 mm.
Length of abdomen, 9 27 mm.
Length of hind wings, S 19 mm.
Length of hind wings, 9 21 mm.
Width of hind wings, $ 4 mm.
"Width of hind wings, 9 3.5 mm.

A species of apparently local distribution, occurring in the lake

region of Illinois. Several collections of nymphs and adults were
made at Lake Villa, July 13 and 14, 1915, and a number of adults

were reared from the nymphs.
While closely related to signatmn, the nymph shows a great dif-

ference in the gills, making it recognizable at sight. It is quite different

from the species figured by Walker as />o//;(f;/;u ('13; pi. i,fig. 10), and
his description also differs from the specimens obtained at Lake Villa.

Enallagma signatum (Hagen)

Nymph.—Color, buff or greenish.

Head elliptical in outline, the caudo-lateral angles not projecting

strongly, but thickly studded with short setae ; first two segments of

the antennae dark in color, nearly equal in length, the second slightly

shorter, the third longest, and the remaining ones decreasing succes-

sively in length ; labium, when folded, extending just caudad of the

procoxae, with three mental setae, five lateral, and three or four

smaller ones on the margin of the median lobe.

Thorax : legs light in color except a dark ring on the apical third

of each femur and the tips of the third tarsal segments; femora with

a few small setae and scattered hairs; metathoracic wing-cases extend-

ing nearly to the fourth abdominal segment.

Abdomen : the segments of the abdomen appear to have a greater

transverse diameter near the apical fourth on account of the projecting

lateral keels; the keels are well developed and setose, the setae being

grouped mainly at one point near the apex of the keel; dorsum of

segments 4—8 with short apical rows of small, heavy setae, terga

nine and ten with longer rows, usually extending onto the venter;

sterna two, three, and four with a cluster of small thick setae on the

apical third, and the venter with a black line extending from the basal

segment to segment nine; gills (Figs. 56, 69) lanceolate, the dorsal

marginal setae of the median gill grouped mainly at one point, usually

just proximad of the point where the first transverse band reaches

the margin; beyond the ventral marginal row of setae the margins
of the lateral gills are distinctly emarginate ; the pigmentation of the



554

gills consists of three to five broad, black cross-bands and a broad

axial band from the bases to the apices ; ovipositor extending to the

middle of the tenth abdominal segment.

Measuremeyits

Length 16-18 mm.
Length of abdomen 10.5-12.5 mm.
Length of gills 5.5 mm.
Width of gills 1.6 nun.

Length of mctathoracie wing-cases. . . .4 mm.
Length of median lobe 2 mm.
Width of median lobe 5-1.8 mm.

Adult; Male.—Color, pale blue or orange, and black.

Head blue or orange, and black; mouth-parts bufY, the median

lobe of the labium subtriangular, the palpi pale ; first two segments

of the antennae pale, at least much paler than the distal ones, the

second segment darker at the tip; postclypeus black, sometimes with

a pair of median pale spots, one on each side of the meson ; anteclypeus

pale; labrum pale, the dorsal margin with a mesa! black spot and

two lateral ones, or with a transverse stripe of black including the

three spots; exposed portions of the mandibles, their trochantins,

genae, and a transverse stripe above the clypeus extending slightly

dorsad of the antennae, orange or blue ; remainder of the front and

vertex black; postocular spots large, cuneiform, and yellow or blue;

postgenae and the occiput largely yellow.

Thorax orange or blue, and black; pronotum black, the cephalic

lobe, a subcircular spot on each median lobe, and the entire caudal

lobe blue or yellow ; the spots on the median lobes are variable, being

frequently subcircular with an emargination on one side; in younger

individuals there are also two smaller spots mesad of the large spots

on each mesal lobe ;
proepimera blue or yellow, the dorsal margins

covered by a black stripe; stigmal plates triangular, the caudo-mesal

angles elevated, and the caudal margins with a blue or yellow stripe

;

dorsal carina covered by a black stripe, the margins of which are

parallel and very straight ; mesopleural suture also with a broad stripe

which is widest just caudad of the mesinfraepisternum and extends

cephalad and covers the dorsal third of that sclerite; remainder of the

thorax pale blue or orange, buff-colored below; paraptera trapezoidal,

black, the cephalic margins and a spot below the lateral angles pale

;

legs usually buff, the femora with an indefinite dorsal brown line and

a row of spots, the tibiae with a faint dorsal line or row of dashes

;



555

tarsi pale, darker at the apices; wings with ten postnodal cross-veins

in the front wing and eight in the hind one ; M, arising near the fifth

postnodal vein in the front wing and between the fourth and fifth

or between the third and fourth, usually near the fourth, in the hind

wing.

Abdomen orange or blue and black ; dorsum of terga i-8 inclusive,

black, except interrupted basal rings on 3-7, lateral surfaces of one

and two, and the lateral margins of 3-8; all of tergum nine and the

lateral surfaces of the tenth orange or blue, the dorsum of ten being

black; anal appendages (Figs. 185,192) dark brown, the superiors

much longer than the inferiors, blunt at the apices, the lateral surfaces

convex, the mesal surfaces somewhat concave; inferiors about half

as long as the superiors and subconical, the tips black and directed

mesad.
Female.—Color, pale blue or orange, and black.

Head similar to that of the male.

Thorax similar in all particulars to that of the male; the orange-

colored females are, however, less frequent; mesostigmal plates (Fig.

214) long, the lateral margins rounded, and a diagonal pale stripe

crossing the plates.

Abdomen blue or orange, and black ; terga 1-9 with black, dorsal,

longitudinal stripes from the bases to the apices, the stripes widened

near the ape.x on 2—7 and narrowed on the ape.x of nine ; lateral surfaces

of all terga, basal rings on 3-7, and an apical ring on one, yellow or

bluish ; all of segment ten yellow or blue ; sterna 3-8 black ; anal ap-

pendages of the usual form ; ovipositor with the lateral valves pale

and serrated on the ventral margins, the prostyles brown.

Measurements

Length, <J 34-35 mm. •

Length, 9 34-35 mm.
Length of abdomen, S 26-28 mm.
Length of abdomen, 9 28 mm.
Length of hind wings, S 17 mm.
Length of hind wings, 5 20 mm.
Width of hind wings, $ 3.5 mm.
Width of hind wings, 9 4 mm.

One of the commonest species in Illinois, occurring in all localities.

Ne.xt to Ischnura verticalis it may be considered as the most abundant.

The nymphs may be collected in slow streams, permanent ponds,

or lakes, and prefer the clear water. They emerge in central Illinois



556

as early as the tenth of May and the greatest number of adults apjjear

on the wing about June i. The latest emergence which is recorded
is one on June 25, 191 5. This gives a period of emergence of at least

a month and a half.

Specimens have been seen from Havana, Lake Villa, Muncie,
Peoria, and Urbana.

Enallagma traviatum Selys

Nymph.—Color, very dark brown.
Head about one-third as long as broad, dark in color ; caudo-

lateral margins projecting caudad, studded with short setae ; antennae
very slender, the first two segments with setae and of much greater

diameter than the remaining ones, the third segment longest, the

second decidedly shorter than the first ; labium extending slightly cau-

dad of the first pair of coxae ; mental setae two, with sometimes a rudi-

mentary third, lateral setae four; marginal setae of the median lobe

six or seven.

Thorax : lateral portions of the prothorax and the metapleura
darker than the dorsum of the thorax ; legs slender, the coxae dark
brown, femora almost wholly devoid of setae, but with very distinct

preapical brown rings; tibiae with setae which are rather closely set,

especially towards the apices ; tarsi pale.

Abdomen brown, darker immediately above and below the lateral

keels ; cuticle with a few minute setae, but lacking minute black spots

entirely ; lateral keels feebly developed and without heavy setae, there

being instead a few setae near the apices of the keels; gills (Fig. 55)
rather narrowly lanceolate, the median gill entirely without heavy
setae on the dorsal margin ; lateral gills with the ventral marginal row
of setae extending one-half or less of the length of the gills; basal

two-fifths or one-half of the gills uniform dark brown, the pigmented
area followed by a broad white or clear band extending from margin
to margin and including the axes ; beyond the clear portions there are

frequently one or two brown transverse stripes, the apex of the gills

being without pigment; ovipositor extending caudad to the apex of

the tenth sternum, the ventral margins of the lateral valves with one
or two heavy setae and a number of hairs.

Measurements

Length 11 mm.
Length of abdomen 8 mm.
Length of gills 6 mm.
Width of gills 1 mm.



557

Length of metathoracic wing-cases. . .3.5 mm.
Length of median lobe 2 mm.
Width of median lobe 5-1.3 mm.

Adult; Male.—Color, pale blue and black.

Head blue and black ; labium buff, the median lobe with a broad

median cleft; distal segment of the labial palpi pale; antennae brown,

the first segment sometimes with the cephalic half blue; postclypeus

blue with a small black spot on each side ; anteclypeus blue ; labrum blue

with a black dorso-mesal spot; exposed portion of the mandibles, their

trochantins, genae, and the front from the fronto-clypeal suture dorsad

to the median ocellus, blue ; lateral ocelli with small blue spots ventrad

of them, and a similar spot between the ocelli ; remainder of the front

black; postocular spots v'ery large, forming equilateral triangles and

occupying most of the dorsal portion of the occiput, the spots bounded

caudad by a very narrow black band and separated from the com-
pound eyes by a band of similar width; the narrow stripe caudad of

the ocellar area is indistinct ; occiput and postgenae pale blue.

Thorax blue and black; pr.onotum blue and black, the cephalic

lobe with a transverse line of blue on the caudal margin, the median

lobes with elongate blue spots, contiguous on the meson, and semi-

crescentic spots of the same color
;
proepimera and proepisterna brown

or pale ; mesothorax with the narrow black stripe covering the dorsal

carina but frequently divided there by a line of brown; black stripe of

the mesopleural suture reduced to a line on the suture; mesinfraepi-

sterna with black crescentic marks on the dorsal borders ; remainder

of the pleura blue with the exception of small spots on the interpleural

folds and metapleural sutures adjacent to the wing bases; postcoxal

areas pale; paraptera black, crescentic, the cephalic margins and lateral

angles blue; legs striped, pale blue or buff and black, the coxae and
trochanters blue, the femora blue with broad dorsal black stripes which
are frequently interrupted at the base by a pale spot ; tibiae pale blue and
buff with a short dorsal black stripe or none, the tarsi pale, black at the

tips ; claws deeply bifid and black at the tips ; wings with ten postnodal

cross-veins in the front wing and eight in the hind one; Mj arising

between the fourth and fifth postnodal cross-veins in the front wing
and between three and four in the hind one ; stigma small, subellip-

tical, and surmounting less than a single cell.

Abdomen blue and metallic black, the dorsum of the first tergum
with a small black basal spot about half the length of the tergum; sec-

ond tergum with a black, apical, shield-shaped spot, the spot extending

to the cephalic margin and narrowed at this point to a line on the me-



558

son ; lerj^a ^rl^ inclusive, witli Icinj^itudinal l)lack stripes widened subap-

ically and narrowed basally, the lateral margins of the terga pale ; terga

eight and nine usually entirely blue, the eighth sometimes with a basal

spot on the dorsum; tenth tergum black; anal appendages (Figs. 199,

206) short and black, the sujicriors slightly longer than the inferiors

and appearing slightly knobbed at the apices when seen in lateral pro-

file; viewed from above, the superior appendages are seen to have
broad basal lobes which are often contiguous on the meson ; inferior

api)endages short, subconical, and directed obliquely dorsad; first

sternum pale, 3-8 black, the tenth pale.

Female.—Color similar to that of the male.

Head similar to that of the male except that the front is paler

and the spots ventrad of the lateral ocelli are larger and connect with

the pale color of the ventral portions of the front; the black borders

of the postocular spots are narrower than those of the male.

Thorax : dorsal stripe divided by a line of brown on the carina

;

mesostigmal plates pale blue, the lateral angles elevated (Fig. 214),
and a sinuate dark stripe on the supraepisterna just caudad of the

plates ; mesopleural suture with a distinct spot cephalad of the wing
bases and the black of the infraepisterna reduced to narrow dorsal

lines
;
postnodal cross-veins of the front wing ten to eleven, of the

hind wing nine to ten.

Abdomen : dorsum of the first tergum with a black basal spot,

2—7, inclusive, with narrow dorsal longitudinal stripes, widened sud-

denly near the caudal margins and narrowed to the meson near the

cephalic margins ; tergum eight blue with a narrow dorsal stripe ex-

tending a little over half the length of the tergum from the base,

(Fig. 94) ; ninth and tenth terga blue; anal appendages of the usual

form; ovipositor with broad, blue, lateral valves; first and second

sterna pale, with black mesal lines, 3-8, inclusive, black.

3Ieasurements

Length, S 31 mm.
Length, ? 31 mm.
Length of abdomen, S 25 mm.
Length of abdomen, 9 25 mm.
Length of hind wings, S .17 mm.
Length of hind wings, 2 18.5 mm.
Width of hind wings, S 3.25 mm.

. Width of hind wings, 9 3.5 mm.



559

This species was collected at Carbondale, 111., June, 1915, and
was reared at that time. It has not been reported elsewhere in the

state but doubtless occurs about glacial lakes and ponds.

The nymph differs from that of cxsiilans chiefly in the darker

color. In all the specimens studied the labium has only two men-
tal setae as compared with three in exsnlans. The gills show con-

siderable difference in the shape and pigmentation, particularly of the

apical portions.

The adult is most closely related to cxsulans, but both sexes may
be distinguished by the reduced amount of black on the mesopleural

suture, the greater amount of blue on the front, and the exceedingly

large postocular spots.

Genus Nehalennia Selys

The nymph of the only representative of this genus occurring in

Illinois is characterized by its peculiar type of gills, in which the

tracheae are much more numerous near the widest portion of the gill

than elsewhere.

The dominant color of the adult is metallic green or bronze, the

mesepisterna being entirely without pale stripes and the pronotum
without pale spots. The female lias the caudal lobe of the pronotum
trilobed and the eighth sternum is without the ventral apical seta.

The sternites at the base of the cephalic pair of gonapophyses arc

minute and scarcely visible.

NehaeEnnia IRENE Hagen

Nymph.—Color, brown or green.

Head oval in outline, the caudo-lateral angles with but few setae

;

antennae with the second segment longer than the first, the second

segment and proximal third of three dark in color ; labium, when
folded, extending nearly to the mesocoxae, with a single large mental

seta and a smaller one alongside; lateral setae five, and the lateral

margins of the median lobe with about five small setae.

Thorax : femora and tibiae with rows of sparsely placed setae,

the preapical rings of brown on the femora very indistinct ; apical

tibial scales present ; wing-cases extending nearly to the apex of the

fourth abdominal segment.

Abdomen slender, with feeble lateral keels, the cephalic two or

three without setae, the caudal ones with not more than six or seven

;

cuticle of the abdomen with small whitish spots on a darker back-

ground
;
gills (Fig. 61) much broader lieyoncl the middle, the lateral



560

gills with ten to twelve black cuticiilar spots on the margins and a

distinct arcuate cross-band just beyond the middle ; tracheal branches

much more numerous beyond the middle of the gill; marginal setae

large and widely separated, the ventral row of the lateral gills ex-

tending about half the length of the gill from the base and the distal

setae much farther apart than the proximal; ovipositor usually ex-

tending beyond the apex of the tenth segment.

Measurements

Length 10-11 mm.
Length of abdomen 8 mm.
Length of gills 4-^.5 mm.
Width of gills 1 mm.
Length of median lobe 1.5-1.7 mm.
Width of median lobe 1.25 mm.

Described from three specimens obtained from Dr. E. M. Walker,
and labeled Toronto, Ont., May 31, 1913.

Adult; Male.—Color, metallic green and pale blue.

Head metallic green above, buff below ; median lobe buff, the cleft

large and rounded at the base ; distal segments of the labial palpi dark
at the tips ; antennae black, the second segment with a pale ring at

the middle; postclypeus shining black, the anteclypeus buff; labrum
pale yellow with a dorsal, transverse, shining black stripe about one-

third the width of the piece; exposed portions of the mandibles, the

trochantins, genae, and the front from the fronto-clypeal suture dorsad

to the antennal fossae, shining yellow ; remainder of the front, vertex,

and a large portion of the occiput, metallic green; postgenae black,

with a pale stripe beneath the compound eyes which is continuous with

the yellow of the genae ; compound eyes brown.

Thorax metallic green and pale blue
;
pronotum metallic green

without paler spots, the margin of the caudal lobe entire; proepimera
buff-colored ; dorsal carina and the mesopleural suture lined with
black; mesosupraepi sterna and the mesepimera except the cephalo-ven-

tral shoulders metallic green ; dorsal margin and about the ventral half

of the mesinfraepisterna pale, the remainder metallic green ; remainder

of the mesopleura and metapleura except a green triangle adjacent

to the wing base on the metepimera, buff or pale blue
;
postcoxal

areas buff or pale blue ; legs pale, striped with black ; coxae and tro-

chanters pale, all the femora with dorsal stripes extending from the

apices nearly to the bases, and the front femora with a short cephalo-



561

ventral stripe including the cephalo-ventral row of setae ; tibiae with
long dorsal stripes extending from a point slightly distad of the femora
to near the apices of the segments; tarsi and claws pale except at

the apices; wings short, the postnodal cross-veins ten in the front

wing, nine in the hind wing; Ma arising between the fourth and fifth

postnodal cross-veins in the front wing and between three and four
in the hind wing.

Abdomen metalHc green and pale blue; terga 1-7, inclusive,

metallic green above, with broad, lateral, pale stripes on one and two,
and narrow lateral stripes and interrupted basal rings on 3-7; eighth

tergum green on the dorsum except at the apex, where there is a tri-

angle of blue, the lateral angles of which are continuous with the

broad blue stripes on the lateral surfaces ; ninth and tenth terga blue

with green basal triangles on each side of the meson ; anal appendages
(Figs.

1 59, 1 60) with the superiors small and tuberculate, the inferiors

much larger than the superiors and toothed at the apices.

Female.—Color, metallic green or bronze, and yellow.

Head similar to that of the male except that within the dark
area of the front there is a pale- spot ventrad of each antennal fossa.

Thorax differing from that of the male in having the caudal

lobe of the pronotum emarginate on each side of the meson, the

piece being trilobed ; the mesostigmal plates (Fig. 182) have the mesal
margins strongly elevated and projecting dorsad ; the front wings have
nine to ten postnodal cross-veins, the hind wings usually nine.

Abdomen with terga 1—8, inclusive, greenish bronze, the lateral

margins pale ; ninth tergum green above, with an apical blue triangle

and blue lateral stripes ; tergum ten blue, with two small green tri-

angles at the base; anal appendages of the usual type; ovipositor, in-

cluding prostyles, extending beyond the apices of the anal appendages,

the prostyles dark.

Measurements

Length, $ 27 mm.
Length, 9 26 mm.
Length of abdomen, $ 21.5 mm.
Length of abdomen, ? 21 mm.
Length of hind wings, $ 15 mm.
Length of hind wings, 9 15 mm.
Width of hind wings, $ 4 mm.
Width of hind wing.s, 5 4 mm.

The species is apparently limited to the northern third of the

state. It was abundant at Lake Villa, July 13, 191 5, and was also

taken at Freeport July 8, 19 15.



562

Genus Amphiagrion Selys

The nymph of the only species of the genus known to occur

in Ilhnois is easily distinguished from other genera by means of the

projecting caudo-lateral angles of the head. The gills are without

cuticular pigment and are decidedly ovate in shape.

The adults are red or brf)wn in color. The stigma of botli front

and hind wings is turned ol)li(|ueIy to the long axis of the wing and
the width is much greater tlian its length. The eighth sternum of

the female possesses a long seta, and the sternites at tlie base of the

cephalic pair of gonapophyses are small but \-isible with moderate
magnification. The superior anal appendages of the male are much
sliorter than the inferiors and the parameres of the ninth sternum do

not reach the apex.

Amphiagrion saucium (Burmeister)

Nyiiiph.^ColoT, dark brown.

Head pentagonal and characterized by having the caudo-lateral

angles projecting strongly and forming a short blunt tubercle; an-

tennae composed of seven segments, the distal segments being short

and similar to those of the nymphs of the genus Argia ; labium broad,

when folded extending to the metacoxae, the median lobe with three

or four mental setae and six lateral setae, and the margins of the

median lobe with ten to twelve setae.

Thf)rax brown; legs without brown rings and uniform in color;

femora indistinctly carinate; tibiae with rather closely set slender

setae; wing-cases extending caudad to the fourth or fifth abdominal

segment.

Abdomen thickset, the lateral keels absent or feebly developed

and without setae ; ovipositor of the female nearly reaching the apex

of the tenth segment in full-grown nymphs; caudal gills (Fig. 59)
transparent, ovate-lanceolate, the apices gradually narrowed to a sharp

point; margins of the gills setose from the proximal to the distal end,

the setae placed closely together and increasing in length towards the

apices ; tracheal trunks sometimes subdividing and forming a number

of large branches near the proximal fourth of the gill.

Mcnsurcments

Length 11-14 mm.
Length of abdomen 7-10 mm.
Length of gills 4.5 mm.
Width of gills 1.5 mm.



56o

Length of metatlioracic wing-eases. . .3.5 mm.
Length of median lobe 1.75-2.0 mm.
Width of median lobe 1.25-1.5 mm.

Described from a single specimen taken at Muncie, 111., April 25,

1914, and several specimens obtained from Dr. J. G. Needham, col-

lected at Galesbtirg, 111., June 3, 1897.

Adult; Male.—Color, very dark brown and deep orange-red.

Head black or dark above, pale below ; labium pale, the median

lobe subtriangular, the cleft shallow and broad at the base; antennae

dark brown, the first two segments subequal in length, the first with

a pale apical ring; postclypeus dark brown; anteclypeus, labrum, ex-

posed portions of the mandibles, their trochantins, genae, and a trans-

verse stripe on the front above the fronto-clypeal suture, pale buff,

the pale area of the front extending dorsad along the margins of the

compound eyes to the level of the antennal fossae ; remainder of the

front and vertex very dark brown, nearly black ; occiput and postgenae

pale.

Thorax dark brown to brick-red and yellowish buff; pronotum

dark
;
proepimera also dark, nearly black ; dorsum of the mesothorax,

including the supraepisterna and the epimera and the caudo-dorsal

angles of the metepisterna, black or dark brown; remainder of the

meso- and metathorax yellowish red ; intersternum projecting ventrad,

conspicuous from the side, and provided with long black setae; legs

yellowish buff, the coxae and trochanters yellowish, the femora slightly

darker above but without distinct stripes ; tibiae entirely pale and the

tarsi pale except at the tips ; femora with rounded dorsal carinae

;

wings with ten postnodal cross-veins in the front wing and about

eight in the hind wing; Mn arising between the fourth and fifth post-

nodal cross-veins in the front wing and between the third and fourth

in the hind one ; stigma reddish, small, surmounting a single cell.

Abdomen red and black ; terga 1-6 dull red, with the exception

of small caudo-lateral black spots on the dorsum of 1-6 inclusive,

and subapical spots on five and six ; terga 7-10 black on the dorsum,

the lateral margins and a broad basal ring on seven reddish; anal

appendages (Figs. 174,178) reddish, the superiors shorter than the

inferiors, flat and the dorsal surface depressed ; inferiors longer, acute,

subconical, the tips directed dorso-mesad ; apical margins of the tenth

tergum emarginate on the dorso-meson and depressed at this point,

forming a deep rounded pit.

Female.—Color in general similar to that of the male but usually

considerably lighter.



564

Head similar to that of the male but lighter in color.

Thorax buff, and not blackish on the dorsum as in the male;
mesostigmal plates as shown in Figure i8r.

Abdomen : terga 1-4 red ; terga 5-7 red with two black spots on
each near the caudal fourth ; terga eight and nine with two longitudinal

black stripes extending from the cephalic margins to within a very
short distance of the caudal margins; tergum ten pale buff; sterna
i-io buff; eighth sternum with a long seta; ovipositor with broad,
buff, lateral valves, the ventral margins serrate

;
prostyles short, brown.

Measurements
I

Length, S 26 mm.
Length, 9 26 mm.
Length of abdomen, S 21 mm.
Length of abdomen, 2 21 mm.
Length of hind wings, S 16 mm.
Length of hind wings, 9 16 mm.
Width of hind wings, S 3.5 mm.
Width of hind wings, 2 3.5 mm.

Adults have been collected at Urbana during the latter part of

May and early part of June, but the species has at no time appeared

in great abundance, and attempts to secure the nymphs from this

locality have failed.

Genus Chromagrion Needham

The nymphs of this genus are characterized by the projecting

caudo-lateral angles of the head and the extremely long and slender

gills, which are without conspicuous marginal setae. The median lobe

of the mentum is provided with mental setae and the proximal seg-

ments of the labial palpi have a single sharp fixed hook and a blunt

process with teeth at the apex. The lateral keels are not well developed

and are without heavy setae.

The adult is characterized by the absence of postocular spots, by
the long, somewhat forcipate, anal appendages of the male, and by
the peculiar formation of the pronotum of the female—as shown in

Figure 170. The parameres of the male extend to the apex of the

ninth sternum.

The genus is represented in North America bv a single species.



565

Chromagrion coNDiTUM (Hagcn)

Nymph.—Color, dark brown.
Head half as long as wide, the caudo-lateral angles projecting

strongly; labium, when folded, extending caudad to the procoxae;
mental setae three and sometimes a small fourth ; lateral setae five

;

proximal segment of the palpus with a distinct hook at the apex of
the mesal process and the median lobe with a slight notch at the apex.

Thorax : femora with two dark rings and a double row of setae

on the ventral surfaces; tibiae with a single basal ring of brown;
wing-cases reaching caudad to the fifth abdominal segment.

Abdomen slender; lateral keels feebly developed and without
setae; gills long and slender, widening gradually to near the apices,

then suddenly contracted, the margins setose, the setae far apart and
increasing in size distad; color of gills uniform dark brown, except

that the tips are light; indistinct blotches of darker pigment occur
around the margins of the gills; smaller tracheae transparent and
indistinct.

Measurements

Length 17 mm.
Length of abdomen 10 mm.
Length of gills 6 mm.
Width of gills 1 mm.
Length of median lobe 2 mm.
Width of median lobe 6-1.6 mm.

Described from fragments of several exuvia obtained from Dr.

J. G. Needham, and the description completed from data given by
Needham in his description of the species ('03: 247).

Adult; Male.—Color, blue, black, and yellowish orange.

Head black and dark brown and buff; mouth-parts yellowish, the

labium pale, the median lobe subtriangular in outline, the cleft broad
and deep ; labial palpi pale, the distal segment also pale ; antennae nearly

black, the first segment nearly as long as the second
;
postclypeus black,

the anteclypeus, labrum, mandibles, their trochantins, genae, and the

front above the clypeus to the level of the antennal fossae, greenish

blue; remainder of the vertex, occiput, and postgenae black.

Thorax black and blue, the pronotum largely black, the cephalic

lobe, a small spot on the lateral margins of the median lobes, and the

lateral margins of the caudal lobe, pale
;
proepimera and pro-

episterna bluish green, the dorsal borders black; mesostigmal
plates long and triangular, the lateral angles pale ; mesepisterna with a



r)66

broad l)lack stripe which, adjoining tlie wing Ijases, is exactly the width

of the two mesepisterna togetiier, Init contracts suddenly shortly

cephalad of this, and again ahout half-way to the cephalic margin of the

mesothorax ; mesinfraepisternuni with an indefinite black spot on the

cephalic border; caudal margins of tlie mesepimera and metepisterna

black, shining, the sclerites themselves pale blue ; metepimera lemon-

yellow, the cephalic half of the ventral margins frequently dark
;
post-

coxal areas vellowish bufY, lateral margins of the intersternum darker;

legs black and greenish jjuff, the coxae usually lilack on the cephalic

surfaces; trochanters black on the dorsum, the femora with a broad,

shining black, dorsal stripe, which encircles the segment at the apex
and is narrowed basally on the front femora; femoral setae of the

front femora, seven and four in the two rows respectively; tibiae

pale buff, with a darker stripe on the ventral surfaces between the

rows of setae, the tips dark; tarsi shining black; wings with eleven

postnodal cross-veins in the front wing and ten to eleven in the hind

one ; stigma surmounting a single cell and much longer than Inroad.

Abdomen blue and black, the first tergum with a short basal

black spot on the dorsum and latero-cephalic angles; terga 2-6, in-

clusive, blue with cephalo-lateral spots of black; second tergum with

an apical shield-shaped spot and an apical ring; terga 3-6 with dorsal

longitudinal stripes, narrowed to a line at the cephalic margins and
widened to the lateral margins at the caudal end of the segment

;

terga eight and nine blue, with narrow lateral stripes on the lateral

margins and mesal stripes from the base to the distal fourth and
small spots on each side of the distal extremity of the lines; tenth

segment entirely black except the small blue spots on the dorsum, one

on each side of the meson; first sternum pale, with a black median spot,

2-g black; anal appendages (Figs. 102,106) black, the superior ap-

pendages longer than the inferiors, slightly swollen at the apices, and

the mesal surfaces densely hairy; inferiors short, pointed at the tip,

the dorsal surface flat, the ventral surfaces convex.

Female.—Color : the blue of the male is replaced by yellowish

buff; the yellow is the same as that of the male.

Head similar to that of the male.

Thorax: pronotum curiously modified, the caudal margins of

the caudal lobe not continuous (Fig. 170) and the median lobe with

a flat lateral projection on each side; proepimera entirely pale; meso-

stigmal plates broad, the caudal margins convex, the lateral angles

more or less acute, and the latero-caudal margins slightly elevated.

Abdomen hufi and black, the first tergum with a black basal spot

and a cephalo-lateral spot on each side ; dorsum of the second tergum



567

with a broad black band from the base to the apex which is widened
subapically, and a narrow apical ring ; terga 3-7 with small dark spots

near the cephalo-lateral angles, broad dorsal longitudinal stripes, nar-

rowed at the base but not to a line, and widened at the apex but not

reaching the lateral margins of the sclerites except on terga five, six.

and seven; terga 7—10 with pale lateral margins and black dorsal

stripes, the stripes narrowed at the caudal end ; anal appendages of

the usual type ; ovipositor short, brown, the prostyles short and blunt,

the eighth sternites at the base of cephalic pair of gonapophyses

large and subtriangular ; sterna 2-7 black, the eighth with a black

median line but without an apical spine.

Measurements

Length, S 35 mm.
Length, 9 36 mm.
Length of abdomen, 3 29 mm.
Length of abdomen, 9 30 mm.
Length of hind wings, $ 21 mm.
Length of hind wings, 9 22 mm.
Width of hind wings, 3 4 mm.
Width of hind wings, 9 4 mm.

Described from a number of specimens in the collection of Mr.

E. B. Williamson. Reported from northern Illinois by Needham
('03:247)-

Genus Ischnura Charpentier

The nymphs of this genus have gills with long tapering points

and one or more arcuate cross-bands. The labium is moderately

broad and the median lobe possesses four or five setae and five or

six, usually six, lateral setae.

The adults may be distinguished from other genera by the pres-

ence of postocular spots, by the origin of vein Mo, which is between

the third and fourth postnodal cross-veins in the front wing and be-

tween the second and third in the hind wing, and by the presence in

the males of a short apical projection of the dorsum of the tenth

tergum, which is, however, not as long as the segment. The sternites

at the base of the cephalic pair of gonapophyses of the female are

very small and do not project beyond the caudal margin of the large

basal sternite of the eighth segment. The parameres of the male do

not extend caudad to the margin of the ninth segment and the anal

appendages are short, the superiors being about as long as, or shorter

than, the inferior appendages.



568

Key to Species

NYMPHS

a. Gills with foin' distinct arcuate cross-bands and a blotch on the tip

of the gill; dorsal marginal setae of the median gill extending one-

third the length of the gill from the base; lateral setae of the labium,

five posUa.

aa. Gills with one or two cross-bands or none, never with four ; dorsal

marginal setae of the median gill extending one-half the length of the

gill from the base; lateral setae of the labium usually six. .vcrticalis.

ADULTS

a. Mesopleural pale stripe of the supraepisterna interrupted at the caudal

third and fonning a distinct exclamation point; eighth sternum of

the female with a long spine posita.

aa. Mesopleural pale stripe of the supraepisterna not interrupted at the

caudal third and not forming a distinct exclamation point; eighth

sternum of the female without a long spine.

b. Seventh tergum with more or less blue on the dorsum. . . .kellicotti.

bb. Seventh tergum black on the dorsum verticalis.

IsCHNURA KELucoTTi Willlamson

Nymph.—Unknown.*
Adiili; Male.—Color, blue and black.

Head blue and black ; labium pale buff, the median lobe subtri-

angular; labial palpi broad, the second segment pale; antennae dark

brown, with a small pale blue spot on the condyle of the scape
;
post-

clypeus black, anteclypeus blue; labrum blue except a black dorsal

marginal line ; exposed portions of the mandibles, their trochantins,

genae, and the front above the fronto-clypeal suture to the antennal

fossae, blue; the blue area of the front is divided by a short black line

on the meson and the blue color extends dorsad above the genae to

the antennal fossae; remainder of the front and the vertex black;

postocular spots large and blue and connected with the blue of the

occiput ; occiput and postgenae except medium-sized black spots on

each side of the occipital foramen, pale blue.

Thorax blue and black
;
pronotum largely black, the cephalic lobe,

caudal margin of the caudal lobe, and four small spots on the median

lobe, near the meson, blue; proepimera blue and black, the caudal

half being largely blue; mesostigmal plates with blue lateral angles;

mesothorax with black supraepisterna which possess narrow longi-

tudinal blue stripes, the stripes narrowed conspicuously at the middle



569

and widened at both ends but not extending: caudad to the paraptera

;

dorsal half of the mesepimera black, the black stripe covering that

portion suddenly widened by a ventral projection just caudad of the

mesinfraepisternum; mesinfraepisterna black except the caudo-ven-

tral angles; remainder of the pleura blue, the interpleural fold and

the metapleural suture, however, lined with black
;
postcoxal areas

mostly pale; legs blue and black; coxae largely blue, the cephalic sur-

faces sometimes spotted with black ; trochanters blue, black above

;

femora with broad dorsal stripes, blue beneath ; tibiae, tarsi, and claws

brown and without stripes ; wings with eight or nine postnodal cross-

veins in the front wing and seven in the hind wing ; stigma subelliptical,

black or blue in the front wing, pale in the hind wing; Mo arising

between the third and fourth postnodal cross-veins in both wings.

Abdomen black, blue, and buff; first tergum blue with the cephalic

half black; second, blue with a broad black lateral stripe on each side

and a narrow apical ring, the stripes extending from the base of the

segment to the caudal third and the two uniting on the meson at the

caudal ends ; terga 3—6 black, with narrow, blue, interrupted basal

ring and lateral marginal stripes; seventh tergum black with pale

lateral stripes and a bkie apical spot on the dorsum ; eighth and ninth

terga blue with broad, black, lateral stripes; tenth tergum black, oc-

casionally with indefinite blue dorsal spots ; anal appendages dark, the

superiors broad, laterally compressed and the ventro-mesal angles hook-
like ; inferiors slightly longer than the superiors, subconical, the tips

black; sterna i-io black.

Female.—Color similar to that of the male.

Head similar to that of the male except that the pale area of the

front is not divided by the mesal black line.

Thorax: the blue of the male is replaced by buff; pale spots of

the pronotum large and occupying nearly the whole of it; pale stripe

of the mesosupraepisterna extending caudad to the paraptera; legs

similar to those of the male, but usually paler in color ; stigma of both
wings brown.

Abdomen : first tergum similar to that of the male ; second, blue,

with a dorsal black spot near the caudal margin and the lateral mar-
gins pale; terga 3-6 black with pale lateral margins; terga 7-10 pale

blue with black lateral margins; anal appendages of the usual type;

ovipositor with broad lateral styles.

Measurements

Length, $ 32 mm.
Length, 9 31 mm.



570

Length of abdomen, S 25 mm.
Length of abdomen, 9 25 mm.
Length of himl wings, S 27 mm.
Lengtli of hind wings, 9 28 mm.
Width of hind wing.s, S 3.5 mm.
Width of hind wings, 9 3.5 mm.

Tills species has not been taken in Illinois, but has been collected

in Indiana by Mr. Williamson, and the above description has been

made from specimens in his collection.

IscHNURA posiTA (Hagen)

Nymph.—Color, usually dark brown.
Head oval or elliptical in outline, the caudo-lateral angles not pro-

jecting and with only a few setae; antennae of the usual form, the

first two segments dark in color, the second light at the tip ; labium

extending between or slightly caudad of the procoxae; mental setae

four and sometimes a small fifth on each side ; lateral setae five ; lateral

marginal setae of the median lobe four.

Thorax about equal in diameter throughout ; femora with rows
of ?etae which become heavier tow-ards the apices ; tarsi pale, the apices

of the third segments brown ; metathoracic wing-cases extending cau-

dad to the fourth abdominal segment.

Abdomen: cuticle provided with numerous black spots usually

bearing a single minute seta ; lateral keels without setae e.xcept those

of the caudal segments; gills lanceolate (Figs. 64, 66), broadest beyond
the middle, usually with four crescentic brownish bands of which the

apical ones are somewhat paler than the proximal, the median gill with

a dorsal row of about fourteen setae extending one-third the length

of the gill from the base ; ovipositor extending to the apex of the tenth

abdominal segment.

Measurements

Length 11.5 mm.
Length of abdomen 7.5 mm.
Length of gills 5-5.5 mm.
Width of gills 1.6 mm.
Length of metathoracic wing-cases. .3.0 mm.
Length of median lobe 2.0 mm.
Width of median lobe 5-1.6 mm.

The nymph is very closely related to verticalis but may be sep-

arated from the latter by means of the shape and figuration of the



571

gills. The lateral setae of the labium do not often exceed five, whereas

there are usually six in vcrticalis.

Adult; Male.—Color, black and sulphur-yellow.

Head black and yellow ; mouth-parts buff, the median lobe sub-

triangular; palpi narrow, the distal segment pale; antennae uniform

dark brown, the second segment considerably longer than the first;

postclypeus shining black ; anteclypeus pale, labrum pale, with a trans-

verse dorsal black stripe which has a slight ventral projection on the

meson; remainder of the labrum, exposed portions of the mandibles

and their trochantins, genae, and the front dorsad of the fronto-clyp-

eal suture to the level of the antennal fossae, shining yellow ; re-

mainder of the front and vertex black, the postocular spots yellow and

circular ; a short yellow line caudad of the ocelli
;
postgenae and occiput

yellow.

Thorax black and yellow
;
pronotum black except the cephalic

lobe, which is yellow; caudal lobe with yellow spots on the lateral

angles ; mesostigmal plates with large oval yellow spots ; mesosupra-

episterna with short yellow stripes and spots adjacent to the parap-

!era, the two together forming anexclamation point on each side of

the dorsal carina ; black stripe covering the mesopleural suture on
each pleuron contracted near the wing bases ; dorsal half of the mes-

infraepisterna and a stripe on the metapleural sutures black, the re-

mainder of the metathorax and the postcoxal areas yellow ; legs black

and yellow, the coxae, trochanters, and femora pale, the femora with

a dorsal stripe on each from base to apex, the stripe widened subapi-

cally ; tibiae with a dorsal black stripe from base to apex which fades

into brown towards the apex ; tarsi and claws pale, darker at the tips

;

wings short, the postnodal cross-veins six to eight and ]\'L arising

between the third and fourth postnodal cross-veins in the front wing
and between the second and third in the hind wing.

Abdomen black and yellow; terga i-io dull black with the excep-

tion of a narrow basal ring on segments 3-7, the stripes narrowed
conspicuously on two and widened on the apices of segments 3—6
inclusive; lateral margins of all terga pale yellow; sterna 3-8 lined

with black on the meson; apex of the tenth tergum with a mesal eleva-

tion at the apex, the elevated portion forming two small tubercles;

anal appendages (Figs. 173,177) small, orange, the superiors large

and blunt and bent ventrad, the inferiors also large, blunt, and bifur-

cate, the arms feeljly divaricate and the dorsal arm with a number of

heavily chitinized teeth.

Female.—Color, pale blue and black.

Head similar to that of the male except that the postocular spots

are blue.



572

Thorax pale blue and I)lack, lacking the black stripes on the meta-

pleural sutures, and the femoral black stripes almost wanting or re-

duced to short sul)apical lines.

Abdomen with the pale and black markings similar to those of

the male; anal appendages of the usual type, the ovipositor with pro-

styles extending caudail to the apex of the anal appendages.

Measurements

Length, 3 24 mm.
Length, ? 29 mm.
Length of abdomen, $ 19 mm.
Length of abdomen, 9 18-22 mm.
Length of hind wings, S 12 mm.
Length of hind wings, 9 13-16 mm.
Width of hind wings, S 2.5 mm.

. Width of hind wings, 5 2.5-3.5 mm.

A common species in southern and central Illinois, occurring in

the same localities where vcrticalis is abundant. The adults appear

usually somewhat later than vcrticalis, and the earliest reared speci-

mens in my collection bear the date June I2, 1915.

Specimens have been seen from Havana, Peoria, and Urbana.

ISCHNURA VERTICALIS (Say)

Nymph.—Color, pale green, buff, or dark brown.

Head broader than long, subelliptical, the caudo-lateral angles

with strong setae ; antennae with the first two segments and the prox-

imal third of three dark, the remainder pale; first two segments sub-

equal, the third as long as the first two together; labium, when folded,

extending slightly caudad of the procoxae, with four or five mental

setae and six lateral setae, the lateral marginal setae of the median
lobe six or seven in number.

Thorax nearly equal in diameter throughout ; front femora with

a strong row of setae on the cephalic surface and all the femora with

preapical rings of brown ; tibiae with several rows of apical setae,

two of which extend far proximad ; wing-cases extending caudad to

the fourth abdominal segment.

Abdomen cylindrical and with feeble lateral keels on segments
T-8, the margins and ventral surfaces being thickly studded with short

setae; cuticle of the abdomen with small dark spots from which minute

setae usually arise, one to each spot; gills (Figs. 62. 65) with long



573

tapering points, the dorsal marginal setae of the median gill usually

extending nearly half the length of the gill from the base, the ventral

row of the same gill consisting of about seven strong setae, consider-

ably farther apart than those of the dorsal row; ventral marginal

setae of the lateral gills extending slightly farther from the base of

the gills than the dorsal row of the median gill
;
pigment of the gills in

the form of one or two arcuate cross-bands near the middle of the

gill; these, however, may be wanting; ovipositor extending to the

middle of the tenth abdominal sternum.

Measurements

Length 13-14 mm.
Length of abdomen 9-10 mm.
Length of gills 6-7 mm.
Width of gills 1-1.3 mm.
Length of median lobe 1.8 mm.
Width of median lobe 6-1.6 mm.

Adult; Male.—Color, black or dark metallic green and pale green.

Head black and yellowish green ; mouth-parts buff, the median
lobe of the labium subtriangular, the cleft short and acute at the prox-
imal end ; antennae black or very dark brown

;
postclypeus black, shin-

ing; anteclypeus, labrum, exposed portion of the mandibles and
their trochantins, genae, and the front above the clypeus, yellow;

postocular spots large and subcircular; vertex, and front except the

stripe above the clypeus, dull black ; occiput black and greenish yellow.

Thorax greenish black and greenish yellow; pronotum shining

black with a transverse yellow stripe on the cephalic lobe ; caudal lobe

of the pronotum with a distinct transverse carina; noto-epimeral suture
indistinct, the proepimera and episterna largely yellow; mesothorax
shining black with a yellow stripe just above the mesopleural suture;

ventral half and cephalic shoulder of the mesepimera yellow; paraptera
trapezoidal, with a yellow spot just ventrad of the lateral angles, the

remainder black; mesostigmal plates black, the caudal margins ele-

vated and lined with yellow ; metathorax including the postcoxal areas,

pale green or yellowish; legs black and yellow, the coxae and tro-

chanters pale with some darker marks on the sutures; femora all with
a broad dorsal stripe, the tibiae with narrower dorsal stripes extending
from near the bases to near the apices ; tarsi and claws pale, dark at

the tips ; wings short, the postnodal cross-veins seven to nine, and M,
arising between the third and fourth postnodal cross-veins in the front

wing and between the second and third in the hind wing.



574

Abdomen shining black or green, and yellowish green; dorsum-
of tcrga 1-7, inclusive, shining black or green with narrow apical ring

on the first, interrupted Ijasal rings on 3-6, and the lateral margins
of j-t) yellow; dorsum of terga eight and nine blue, with short lateral

black stripes on each side about half the length of the segment ; tergum
ten black, the lateral margins pale, the caudal margin with a short

forked process on the meson; sterna 3—9 with a mesal line of black;

anal appendages (Fig. 168) short, the superiors flat and placed nearly

vertically ; inferiors longer, and with a dorsal, basal knob and a larger,

subconical ventral lobe.

Female—Color, orange and black or entirely black.

Head similar to that of the male except that the yellowish green

markings are replaced with orange.

Thorax orange and I)lack
;
pronotum with an orange spot on each

median lobe ; margin of the caudal lobe with orange spots ; mesostigmal
plates (Fig. 180) with caudal elevated margins orange in color; meso-
pleural pale stripe of the supraepisterna orange and much broader

than the pale stripe of the male ; dorsal third and caudal margin of

the mesinf raepisterna black, the remainder pale orange ; metathorax
orange ; legs orange and black, the femora entirely pale except at the

tips, the tibiae with the usual dorsal stripes.

Abdomen orange and black, the first two segments entirely pale

except a narrow ring on the caudal margin of the second ; terga three

orange with an apical spot and ring; dorsum of terga 4-8 black, with

pale basal rings on 4-6 and the apical third of eight also pale ; terga

nine and ten indefinitely marked with black, there being an orange

spot and apical ring of orange on nine and a dorso-mesal line on the

same; lateral margins of all the terga orange; sterna 1-8, inclusive,

with a mesal black line, the eighth sternum with a heavy spine; anal

appendages of the usual type ; the ovipositor with dark brown pro-

styles and pale lateral valves.

In older specimens the orange color becomes black and pollinose

so that it is difficult to distinguish the species on the wing from some
of the Enallagmas whicii also have a tendency to become dark.

Measurements

Length, S 20 mm.
Length, 9 30 mm.
Length of abdomen, S 22 mm.
Length of abdomen, 9 23-24 mm.
Length of hind wings, $ 14 mm.
Length of hind wings, 9 17 mm.
Width of hind wings, 3 3.5 mm.
Width of hind wings, 5 3.5 mm.



575

The commonest species in Illinois, occurring practically where-

ever there is enough permanent water for the nymphs to live. The
adults appear early in May and continue to emerge until September

and possibly later.

Specimens have been seen from Dubois, Carbondale, Golconda,

Havana, Lake Villa, Mahomet, Muncie, Peoria, Urbana, and Vienna.

Genus Anomalagrion Selys

The nymphs of this genus are characterized by their unusually

small size, by the presence of a very slender tip to the gills, and by

the absence of setae on the lateral keels.

The male adults are unique in having the stigma of the front

wing removed from the margin and in the possession of a long process

on the dorsum of segment ten. The sternites at the base of the cephalic

pair of gonapophyses of the female are wanting, and the parameres of

the ninth sternum of the male do not reach the apex of the segment.

Anomalagrion hastatum (Say)

Nymph.—Color, green or buff.

Head with the caudo-lateral angles rounded and without setae;

antennae with the first two segments dark brown, the remaining ones

light in color; second segment about as long as the first or slightly

longer; labium not extending caudad of the procoxae and about as

broad as long; mental setae four, lateral setae five.

Thorax narrower than the head ; legs without dark rings and with

few setae, the tibiae with the usual apical scales ; wing-cases extending

nearly to the fourth abdominal segment.

Abdomen uniform in color; lateral keels feebly developed and
without setae; gills (Fig. 60) lanceolate, with a long point; marginal

.-etae of the median gill consisting of a thick dorsal row, extending

about one-third the length of the gill from the base, and a scattered

ventral row at the base ; ventral marginal row of setae of the lateral

gills slightly longer than the dorsal row of the median gill; ovipositor

extending to the caudal margin of the tenth abdominal sternum.

Measurements

Length 9.5 mm.
Length of abdomen 5.5 mm.
Length of gills 4.5 mm.
Width of gills 1.0 mm.
Length of median lobe 1.6 mm.
Width of median lobe 0.5-2.0 mm.



576

Adult; Male.—Color, pale lemon-yellow and black.

Head lemon-yellow and metallic black; mouth-parts buff, the
median lobe with a wide cleft which is oljtuse at the proximal end;
antennae dark brown except the proximal segment, which has a pale
stripe from the base to the apex

;
postclypeus shining black ; anteclypeus

pale ; labrum with a transverse black stripe on the dorsal margin, the

remainder yellow ; exposed portions of the mandibles, their trochantins,

the genae, and the front above the fronto-clypeal suture to the antennal
fossae, yellow; remainder of the front and the vertex metallic bronze
with the exception of very small postocular spots, a small yellow
spot ventrad of the median ocellus, and a narrow yellow stripe caudad
of the ocellar area.

Thorax greenish yellow and metallic black ; cephalic lobe of the
pronotum with a yellow transverse stripe ; median lobes metallic black

;

caudal lobe black with three short marginal dashes; noto-epimeral
suture indistinct; dorsal carina of the mesothorax feebly developed,

the mesothorax largely black with a narrow yellow line just dorsad
of the mesopleural suture ; dorsal half of the mesosupraepisterna black

;

metepisterna and epimera yellow or buff; paraptera trapezoidal, the

cephalic margins with a pale line ; coxae pale yellow, the femora pale,

with dorsal black stripes widened distad ; tibiae pale, with short, prox-
imal, dorsal and ventral dark stripes, the tarsi and claws pale except

at the tips ; setae of the front femora few, about three in each row, the

distance between them much greater than their length ; wings (Figs. 82,

83) very short; postnodal cross-veins six in the front wing and five in

the hind ; M2 arising near the third postnodal vein in the front wing
and between the second and third in the hind wing ; stigma of the front

wing ovoid, remote from the margin, the stigma of the hind wing
rhomboidal and in contact with the margin of the wing.

Abdomen yellow and orange, the black confined to longitudinal

dorsal bands on terga 1-3 and six, the stripe on three and the one on
six being conspicuously widened subapically; basal and apical black

spots present on the fourth and fifth terga, and a dorsal stripe on seven
which is about three-fourths the length of the segment; the narrow
basal ring on segments 1-7 is interrupted on the meson in all except
the first; tenth tergum with a dorsal process about as long as the

segment and bifurcate at the apex; anal appendages (Figs. 166, 167)
small, the superiors bifurcate, and with a broad mesal lobe extending
caudo-ventrad and a conical lateral one projecting caudad; inferiors

conical, slightly longer than the superiors.



577

Female.—Color, orange and black or dark brown.

Head orange and black, differing from that of the male in having

the black of the postclypeus reduced to a dorsal line and that of the

labrum to lateral spots
;
postocular spots wanting, the caudal margins

of the head with a broad orange stripe ; occiput and postgenae pale.

Thorax : prothorax as in the male except that the black of the

pronotum does not extend as far onto the lateral aspect ; dorsal black

stripe of the mesothorax extending on each side of the dorsal carina

one-half the width of the supraepisterna; mesopleural suture with a

black line, the remainder of the thorax orange and buff ; mesostigmal

plates as shown in Figure 164.

Abdomen orange, with narrow basal black rings on terga 2—4
inclusive, a longitudinal dark stripe on the caudal three-fourths of

five, similar stripes extending the full length of six, seven, and eight,

and two triangular spots at the base of the ninth; dorsum of the

tenth tergum with a short blunt projection; anal appendages short;

ovipositor long and extending caudad of the anal appendages
;
prostyles

short and blunt.

Measurements

Length, $
.' 23 mm.

Length, $ 24.5 mm.
Length of abdomen, S 17 mm.
Length of abdomen, 9 19 mm.
Length of hind wings, $ 10.5 mm.
Length of hind wings, 9 14 nam.

Width of hind wings, $ 1 mm.
Width of hind wings, 2 2-2.5 mm.

This species is rather more common in the southern half of the

state than in the northern. It appears on the wing as early as June 20
at Urbana, but has been taken at Carmi, June 14, 1915.

BiBUOGRAPHY

The following bibliography has been made as complete as possible

in literature dealing with the nymphs. The remaining portion is in-

tended to include the works referred to in the preceding pages and
also the more important systematic publications, such as monographs
and catalogues. To persons beginning a study of the Odonata, Mutt-
kowski's "Catalogue of the Odonata of North America" and Calvert's

''Progress in our Knowledge of the Odonata from 1895 to 1912"
should be considered indispensable. In these two works, most of the

literature appearing previous to 1912 is cited. A number of important



578

articles have appeared since tliat date, and an attempt has also been
made to include tliese in this bibliography.

NYMPHS
Backhoff, Paul

'lo. Die Entwicklung des Copulati<Misapparates von Agrion. Ein
Beitrag zur postembryonalen Entwicklungsgeschichte der Odo-
naten. Zeit. wiss. Zool., 95: 647-706, pi. 21.

Bal four-Browne, F.

'09. Life-history of the agrionid dragonfly. Proc. Zool. Soc. Lon-
don, 1909: 253-285, pis. 22>, 24.

Bervoets, R.
'13. Sur le systeme tracheen des larves d'Odonates. Ann. Biol.

Lacustre, 6: 15-32, figs. 1-3.

Borner, C.

'09. Neue Homologien zwischen Crustaceen und He.xapoden. Die
Beissmandibel der Insekten und ihre phylogenetische Bedeu-
tung. Archi- und Metapterygota. Zool. Anz., 34 : 100-125.

Brimley, C. S.

'04. Note on duration of larval stage of Odonata. Ent. News,
15:136.

Butler, Hortense
'04. The labium of the Odonata. Trans. Am. Ent. Soc, 30 : 1 1 1-

134, pis. 2-7.

Calvert, P. P.

'00. Moults in the Odonata. Entomologist, 33 : 350.
'11. Studies on Costa Rican Odonata. Ent. News, 22:49-64,

pis. 2, 3.

'15. Studies on Costa Rican Odonata. Ent. News, 26: 385-395,
pis. 15-17.

Forbes, S. A.
'88. On the food relations of fresh-water fishes. Bull. 111. State

Lab. Nat. Hist, 2 : 485.

Gilsnn, G., and Sadones, J.

'96. Larval gills of Odonata. Trans. Linn. Soc. London, 25 : 413.

Hagen, H.
'80. Essai d'un synopsis des larves des Caloptervgines. Ann. de

la Soc. Ent. de'Belgique, 23 : LXV-LXVIL



579

Heymons, R.
'96. Grundziige der Entwickelung und des Korperbaues von Odo-

naten und Ephemeriden. Anhang zu den Abhandl. Konigl.

Preuss. Akad. Wiss. Berlin, 1896. 66 pp., pis. i, 2.

'04. Die Hinterleibsanhiinge der Libellen und ihrer Larven. Ann.
k.k Naturhist. Hofmus., 19 : 21-58, pi. i.

Kennedy, C. H.
'15. Notes on the life history and ecology of dragonflies (Odo-

nata) of Washington and Oregon. Proc. U. S. Nat. Mus., 49:
259-345-

Lucas, W. J.

'12. Early stages of British Odonata. Rep. Lancash. Ent. Soc,
35: 17-24-

Lyon, Mary B.

'15. The ecology of the dragon-fly nymphs of Cascadilla Creek.

Ent. News, 26: 1-15, pi. i.

Needham, J. G.

'03. Life histories of Odonata, suborder Zvgoptera. Damsel
flies. Bull. N. Y. State Mus., 68: 2 18-279,' pis. 11-19.

'11. Descriptions of dragonfly nymphs of the subfamily Calop-
teryginae. Ent. News, 22: 145-154, pis. 4, 5.

'iia. Notes on a few nymphs of Agrioninae (order Odonata) of

the Hagen collection. Ent. News, 22: 342-345, pi. 11.

Pierre, I'Abbe

'04. Sur I'eclosion des ceufs de Lcstcs viridis. Ann. Soc. Ent.

France, 73 : 477-484. pl- 4-

Riley, C. F. C.

'12. Observations on the ecology of dragon-fly nymphs : reactions

to light and contact. Ann. Ent. Soc. Amer., 5 : 273-292.

Ris, F.

'09. Odonata. Die Siisswasserfauna Deutschlands, Heft 9.

Rousseau, E.

'09. fitude monographique des larves des Odonates d'Europe.
Ann. Biol. Lacustre, 3 : 300-366, figs. 1-47.

Sadones, J.

'95. L'appareil digestif et respiratoire larvaire des Odonates. La
Cellule, 1 1 : 273-324, pis. 1-3.



580

Tillyard, R. J.

'06. Life history of Lcstcs Icda Selys. Proc. Linn. See. N. S.

Wales, 31 : 409-423, pis. 32, 33.
'11. On the genus Corduleplwa. Proc. Linn. Soc. N. S. Wales,

36:388-422, pis. II, 12.

'12. On the genus Diphlebia, with descriptions of new species and
life histories. Proc. Linn. See. N. S. Wales, 36: 584-604, pis.

19-20.

Van der Weele, H. W.
'06. Morphologie und Entwicklung der Gonapophysen der Odo-

naten. Tijdschr. v. Ent., 49:99-198, pis. 6-8.

Walker, E. M.
'13. New nymphs of Canadian Odonata. Can. Ent., 45 : 1 61-170,

pis. I, 2.

'14. The known nymphs of the Canadian species of Lestes. Can.

Ent, 46: 189-200, pis. 13, 14.

'14a. New and little-known nymphs of Canadian Odonata. Can.

Ent., 46: 349-357. 370-377. pis. 23, 25.

Warren, A.
'15. A study of the food habits of the Hawaiian dragonflies or

pinau. College of Hawaii Publications, Bull. 3, pis. 1-4.

Wesenburg-Lund, C.

'13. Odonaten-Studien. International Revue, 6: 155-228, 373-
422.

ADULTS
Banks, N.

'92. A synopsis, catalogue, and bibliography of the neuropteroid

insects of temperate North America. Trans. Am. Ent. Soc,

19
: 327-373-

Brandt, A.
'69. BeitrJige zur Entwickelungsgeschichte der Libelluliden und

Hemipteren, mit besonderen Beriicksichtigung der Libelluliden.

Mem. Acad. Imp. des Sci. St. Petersb., sen 7, 13 : 1-33, pis. 1-3.

Brauer, F.

'68. Verzeichniss der bis jetzt bekannten Neuropteren im Sinne

Linne's. Verhandl. d. k.-k. zool.-bot. Gesell. Wien, 18:359-

416, 711-742.



581

Calvert, P. P.

'93. Catalogue of the Odonata (dragonflies) of the vicinity of

Philadelphia, with an introduction to the study of this group of

insects. Trans. Am. Ent. Soc, 20: I52a-i52d; 153-272, pis.

'08. The composition and ecological relations of the odonate fauna

of Mexico and Central America. Proc. Acad. Nat. Sci. Phila.,

60: 460-491.
'08a. Odonata. Biol. Centr.-Amer., Neuroptera, pp. V-XXX, 17-

410, pis. 2-10.

'12. Progress in our knowledge of the Odonata from 1895-1912.

Trans. Sec. Intern't'l Congr. of Ent., pp. 140-157.
'13. The species of Nehalennia (Odonata). Ent. News, 24: 310-

316.

'13a. The fossil odonate Phenacolestes, with a discussion of the

venation of the legion Podagrion Selys. Proc. Acad. Nat. Sci.

Phila., 65 : 225-272, pi. 14.

Calvert, P. P., and Hagen, H. A.
'02. (See Hagen and Calvert)

Hagen, H.
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'75. Synopsis of the Odonata of North America. Proc. Bost. Soc.

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Hagen, H. A., and Calvert, P. P.

'02. Illustrations of Odonata : Argia, with a list and bibliography

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Handlirsch, A.
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Kellicott, D. S.

'99. The Odonata of Ohio. Ohio State Acad. Sci., Special Pa-

pers, No. 2. 114 pp., figs. 1—39.

Kennedy, C. H.
'02. A list of the dragonflies of Winona Lake. Proc. Ind. Acad.

Sci., 1902 : 159-164.
'02a. A new diagnostic character for the species of the genus

Argia. Proc. Ind. Acad. Sci., 1902: 164-169, pis. i, 2.



582

Kirhy, W. F.

'90. Synonymic catalogue of Neuroptera Odonata, or dragonflies,

with an appendix of fossil species. 202 pp. London and Berlin.

Lucas, W. J.

'00. British dragonflies (Odonata). 356 pp., 27 pis. London.

Marshall, W. S.

'14. On the anatomy of the dragonfly, LihcUula qnadrimaciilata

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755-786, pis. 69, 70.

Morgan, Anna H.
'13. A contribution to the l)iology of the May-flies. Ann. Ent.

Soc. Amer., 6: 371-413, pis. 42-54-

Muttkowski, R. A.
'08. Review of the dragon-flies of Wisconsin. Bull. Wis. Nat.

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'10. Catalogue of the Odonata of North America. Bull. Pub.

Mus. City of Milwaukee, Vol. i, Art. i. 207 pp.

Needham, J. G.

'03. A genealogic study of dragon-fly wing venation. Proc. U. S.

Nat. Mus., 26: 703-764, pis. 31-54.

Packard, A. S.

'68. On the development of a dragon-fly (Diplax). Proc. Bost.

Soc. Nat. Hist., 11 : 365-372.

Poulton, E. B.

'06. Predaceous insects and their prey. Trans. Ent. Soc. London,

1906:323-409.

Ridgway, R.
'12. Color standards and color nomenclature. 43 pp., 53 pis.

Washington.

Ris, F. ,

'96. LTntersuchung iiber die Gestalt des Kaumagens hei den TJbel-

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Scudder, S. H.
'90. The tertiary insects of North America. Rep. U. S. Geol.

Surv. Terr., XHL 663 pp., 28 pis.

Sellards, E. H.
'06. Tvpes of Permian insects. Am. Jour. Sci., ser. 4, 22 : 249-

258.'



583

Selys-Longchamps, Edm. de
'62. Agrionines. 2'"° Legion.-Lestes. Bull, de I'Acad. Roy. des

Sci., des Lettres, et des Beaux-Arts de Belgique, ser. 2, 13.

291-338.
'65. Synopsis des Agrionines- [Argia]. Idem, 20 : 375-417.
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41 : 247-322, 496-539- 1^33-1309; 42:490-531. 952-991-

Selys-Longchamps, Edm. de, and Hagen, H. A.

'54. Monographic des Calopterygines. 291 pp., 14 pis.

Snodgrass, R. E.
'09. The thorax of insects and the articulatifin of the wings. Proc.

U. S. Nat. Mus., 36: 51 1-595, pis. 40-69.

Thompson, O. S.

'08. Appendages of the second ahdnminal segment of male dragon
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figs. 17-28.

Walsh, B. D.
'62. List of the Pseudoneuroptera of Illinois contained in the cab-

inet of the writer, with descriptions of over 40 new species, and
notes on their structural affinities. Proc. Acad. Nat. Sci. Phila.,

1862: 361-401.

Williamson, E. B.

'00. The dragonfhes of Indiana. Dept. Geol. and Nat. Resources,

Ind., Rep. 24: 233-333, pls. 1-7.

'00a. Notes on a few Wyoming dragonflies. Ent. News, 1 1 :

453-458, pi. 9.

'12. Hetacrina titia and tricolor (dragonflies-Odonata). Ent
News, 23: g8-ioi.

'12a. The dragonfly Argia inocsta ;md a new species (Odonata).
Ent. News, 23 : 196-203.

Wilson, C. B.

'09. Dragonflies of the Mississippi valley collected during the pear'

mussel investigations on the Mississippi River, July and August.

1907. Proc. V. S. Nat. Mus., 36: 653-671.



584

TNDKX TO GENEEA AND SPECIES

Aoshna, 463.

Agiioii, 412, 417, 421, 442, 465, 466,

472.

apquabilc, 46"), 467-469.

yakima, 438, 467.

maculaluiii, 438, 465, 467, 468, 469-

471.

viigo, 439.

.Vmphiagrioii, 465, 499, 500, 562.

sauciuni, 465, 562-564.

.\i!ax Junius, 412.

Anoinal;if;rion, 465, 500, 501, 575.

hastatiim, 465, 575-577.

Argia, 417, 421, 430, 444, 465, 499,

500, 501, 562.

apicalis, 445, 465, 502, 503-506, 507,

512, 514.

fumipennis, 465, 502, 503, 506-507.

moesta putrida, 438, 465, 501, 502,

503, 507-510.

piitrida, 440.

sedula, 46.5, 502, 503, 510-511.

tibialis, 440, 465, 502, 503, 511-514.

violacea, 465, 502, 503, 515-517.

Calopteryx, 413, 442.

Virgo, 439.

Chromagrion, 427, 465, 499, 500, 564.

eonditum, 465, 56.5-567.

Cora, 451, 457.

Knallagma, 42.3, 465, 500, 501, 517.

anteiinatum, 438, 445, 465, 518, 520,

521-,524.

aspersiiiM, 465, 519, 520, 524-525.

ealverti, 465, 476, 500, 518, 520, 521,

525-528, 536.

carunculatiim, 442, 465, 476, 518,

519, 520, .527, 528-531, 532, 533,

534, .539, 540, 550.

civile, 445, 465, 476, 518. 519. 521,

527, 528, 531-534, 539, 540, 5,50.

Enallagma

—

continued.

cyathigerum, 465, 500, 518, 520, 521,

528, 534-536.

divagans, 465, 476, 520, 521, 536-

538.

doubledayi, 465, 476, 519, 521, 528,

538-540.

ebrium, 465, 520, 540-541.

oxsulans, 442, 465, 518, 520, 521,

522, 524, 538, 542-544, 559.

gcminatum, 442, 465, 517, 519, 520,

544-547.

hageni, 439, 445, 465, 517, 520, 534,

547-550.

piscinarium, 465.

pollutiim, 465, 518, 519, 521, 550-

553.

pukhcllum, 439.

signatum, 438, 443, 465, 518, 519,

521, 544, 553-556.

tiaviatum, 465, 518, 519, 521, 556-

559.

Enphea, 457.

Oomphus, 430, 463.

Hetaerina, 417, 426, 434, 435, 444,

46.5, 466, 467, 471.

americana, 445, 465, 471—474, 475.

titia, 465, 471, 474-^76.

tricolor, 476.

Ischnura, 435, 465, 500, 501, 567.

elegans, 439.

kellicotti, 465, 568-570.

posita, 465, 568, 570-572.

verticalis, 423, 438, 439, 440, 442.

443, 445, 465, 555, 568, 570, 571,

572-575.

Le.stps, 418, 421, 422, 427, 430, 435,

438, 439, 440, 442, 444, 451, 465,

477, 485, 492.

congener, 465, 477, 478, 479-482.



58o

Lestes

—

continued.

ilisjiinctus, 465, 476, 478, 479, 4S1,

482-483, 485, 487.

ourinus, 465, 478, 479, 483-4S5.

forcipatus, 465, 476, 478, 479, 483,

485-487, 490, 492, 494, 496.

inaequalis, 46.5, 478, 479, 485, 487-

489.

rt>ctai)giilaris, 443, 465, 478, 479,'

483, 487, 489-492, 494, 496.

inu-atus, 465, 477, 478, 479, 492-

494, 496.

iingiiiculatus, 465, 478, 479, 492,

494-496.

visila-x, 445, 465, 478, 479, 485, 489,

496-499.

Nohalpnnia, 427, 465, 499, 500, 559.

irene, 46.5, 559-561.

Sympetrum striolatum, 439.



r)HG

ABBREVIATIONS USED IN LETTERING PLATES

A, anal vein

Ai-A,„ abdoMiiual segments 1-11
aai, anal appendages of adult-inferior

aas, anal appendages of adult-superior

ag, accessory genitalia of male
ane, antenodal cross-veins

ant, antennae
arc, arculus

awp, anterior wing-process
br, bridge
bsp, basilar space

C, costa

cd, cardo

ce, comjiound eyes

ei, eerci

cl, cardella

cly, clypeus

cr, chitinous rod of the subnientum

Cui, Cuj,cubitus-branches of

cw, claws

ex, coxa
cxp, coxal process

dc, dorsal carina

epcs, epicranial furrow
epm, epimeron .

f, front

fe, femur
fi, fureal invaginations

fl, furcella

fs, femoral setae

g, gills-eaudal

ga, galea

gb, genital lobe

gd, gills-dorsal

glc, galea-lacinia

gn, genae
hm, hamiiles

^

hp, hypopharj'nx

ieps, infraepisternum

insu, interpleural suture

ints, interstermim

lb, labium
Ibr, labrum
le, lacinia

Ik, lateral keel

Ip, labial palpus

Ipi, lp2. labial palpus-first and second seg-

ments
Is, lateral setae of labial palpus

M, media
M,,-M4, media, branches of the

mapl, metapostseutellum

masi.



Fi-



587

pn,



PI.ATE LVllI



Plate LIX

Nijmplutl Structures

Fig. 14. Lcstcs rcctangularis, wing-case.

Fig. 15. Hetaerina americami, wing-case.

Fig. 16. EnaJlagma signntum, wing-case.

Fig. 17. The same, young nymph, wing-case.

Fig. 18. IxdiHuru verticdlis, caudal end of the abdomen
with the two lateral gills removed.

Fig. 19. EudUagmu exsulans, tarsus.

Fig. 20. The same, leg.

Fig. 21. I.schnura vertical is, dorsum of mcso- and
metathorax.

Fig. 22. Agrion macuhitum, maxilla.
Fig. 23. Hetaerina americana, dorsum of the prothorax.
Fig. 24. Isclmiira verticalis, ventral aspect of thorax

and cephalic segments of abdomen.
Fig. 25. The same, lateral aspect of thorax and ab-

domen.
Fig. 26. Enallagma sp., cross-section of gills.



Plate LIX

'eps mcp^ mtcp



Plate LX
Nymphal and Adult Structures

Fig. 27. Isclinura verticalis, adult, ventral asjx'ct of ])ro-

thorax.

Pig. 28. The same, adult, maxilla.

Fig. 29. Hctaerinn anu rirana, adult, ventral aspect of pro-

thorax.

Fig. SO. Iscltnura vcrUciiIi.s, adult, eaudal a.s])eet of head.
Fig. 31. Pleeoptera nymph, maxilla.

Fig. 32. Isclinura verticals, adult, cephalic aspect of head.
Fig. 33. Hetaerina americana, adult, ventral view of the

second abdominal segment of the male.
Fig. 34. The same, adult, anal ai)])endages, dorsal view.

Fig. 35. T.'^rlinura verticalis, adult, leg.

Fig. 36. The same, adult, lateral view of ]irotlioi'ax.

Fig. 37. The same, adult, labium.
Fig. 38. Hetaerina americ<nia, adult, latei'al view of anal

appendages.
Fig. 39. The same, adult, lateral view of prothorax.



Plate LX

cxp



Platk LXI

Tliofdcic >Sirucl iir<s of AiJiiUs

Fi.n'. 40. IIcldcriiKi (ntu ricdiid. vciitr;il aspect of the niesii- and ineta-

thorax.

Fig. 41. Hctaerina iUin, ddi'sal a.speet of nicso- aiul iiictathorax.

Fig'. 42. Isclinura veHicdlis, ventral aspect of mcso- and inctathorax.

Fig. 43. The same, lateral aspect of nieso- and metatliorax.

Fig. 44. The same, dorsal aspect of meso- an<l iiietathorax.

Fig. 45. Hcfdcrina umi rivmid. lateral aspect of nieso- and meta-

thorax.

Fig. 46. The same, dorsal view of meso- and metatcrga.

Fig. 47. Isclinura veriiciilis, dorsal view of meso- and mcTiiterga.



Plate LXI



Plate LXII

Caudal Gills of Nymplis*

Pig. 48. Lestes vigilax. Fig. 53. Enallogma exsulans.

Fig. 49. Lestes forcipcdus. Fig. 54. Enallagma antcnnaium.
Fig. 50. Lestes congener. Fig. 55. Enallagma iraviatum.

Fig. 51. Lestes imguiculatus, Fig. 56. Enallagma signafum.
normal gills. Fig. 57. Enallagma pollutum.

Fig. 52. The .same, dark gills.

*ODe of the lateral gills removed in most cases.



Plate LXII

,JB*<-



Plate LXIII

Caudal Clills of XiiJiiplis'^

Fifi-. 58. Arjjia niocila pulrida. Fig. 05. [.sclntiini vciiicalis,

Fig. 59. Amphiacjrion sauciutn. young nymph.
Fig. 60. Anomahigrion liasfafiim. Fig. 66. Ischnu7-a posita.

Fig. 61. Nclialennia ireiic. Fig. 67. Argia apinills.

Fig. 62. Isrlniurd vcrlicalls. Fig. 68. Argia lihialis.

Fig. 63. Argia viohicen. Fig. 69. EnaUagma signfifiim,

Fig. 64. Isclniura posita. variations in pig-

mentation.

*One of the latPiMl gills lemoveil in cases where the gills are attached to the
3b<lonieii.



Plate LXllI



Plate LXIV

Caudal Gills of Nymphs* and Wings of Adnlfs

Fig. 70. Enallagma caritnculatum,

gills.

Fig. 71. Enallagma cijatJiigerum,

gills.

Fig. 72. Enallagma gcminatum,
gills.

Fig. 73. Agrion acquahile, wings.
Fig. 74. Iletacrina amcricana,

wings.
Fig. 75. Enallagma civile, gills.

*Onc of the Iriteral yills reinoveil in cases where the K''"s are attached to the

abdomen.

Fig. 76. Enallagma liagcni, gills.

Fig. 77. Enallagma cxsulans, dark
and light gills.

Fig. 77a. The same, abnormal gills.

Fig. 78. Hetaerina amcricana,
male, wings.

Fig. 79. The same, nymphal skin.

Fig. 80. Enallagma (?) calverti,

lateral gill.



Plate LXIV



Plate LXV
Wings of Adults

Fig. 81. Isclinurd vcrticdlis. Fiu'. SO. Tsclinura jMsitn.

Fig. 82. Annnuildyrion lutstdtuin, Fi^'. 87. En<dl<t<jm(i luigcnl.

female. Fig. 88. XelmJcnnia ircnc.

Fig. 83. The same, male. Fig. 89. Ampliitigrion sditcimn.

Fig. 84. Chromagrion conditiim. Fig. 90. Argia apicalis.

Fig. 85. Lesies rcctangularis.



Plate LXV

Ri»SC2,

RitSCa ^St



Pl.\te LXVI

Abdominal Structures of Adults

Fig. 91. Enallagma carunculutum, female, dorsal view of alxlonicii.

Fig. 92. Enallagma civile, female, dorsal view of abdomen.
Fig. 93. Enallagma cj/athigcrum, female, dorsal view of abdomen.
Fig. 94. Enallagma' iravialnm, female, dorsal view of abdomen.
Fig. 95. Enallagma aspirsnm, female, dorsal view of alxlmncii.

Fig. 96. Enallagma gcminalum, female, dorsal view of abdc.iiicn.

Fig. 97. Enallagma caninrulal um, male, penis.

Fig. 98. Enallagma cijathigerum, male, penis.

Fig. 99. Enallagma carunculatmn, female, caudal abdominal segments.
Fig. 100. Anomalagrion liastatum, female, caudal alidominal segments.
Fig. 101. Enallagma liageni, male, penis.

Fig. 102. Clironiagrion conditum, male, anal appendages.
Fig. 103. Enallagma civile, male, anal appendages.
Fig. 104. Isclinura vcrticalis, fenuilc, caudal al)dominal segments.
Fig. 105. Enallagma civile, male, penis.

Fig. 106. Clnrimagrion conditum . male anal appendages.
Fig. 107. Enallagma ehrium, male, penis.

Fig. 108. Enalleigmn calverti, male, penis.



Plate LXVI



Plate LXVII

Abdominal Strtictures of Adults

Fijr. 109. AgriuH vutcuhtium, female, caudal end of abdomen.
P^ig. 110. Acjrion aequabile, female, caudal end of abdomen.
Pig. 111. Hciaerina iitia, female, caudal end of abdomen.
Fig. 112. Heiaerina amcricann , female, caudal end of abdomen.
Fig. 113. Lesies uncdlus, female, caudal end of abdomen.
Fig. 114. Lestes forcipalus, female, caudal end of abdomen.
Fig. 115. Lestes rectdngjilaris. female, caudal end of abdomen.
Fig. 116. Argia vwesta putrida, female, eatidal end of abdomen.
Fig. 117. Agrion aequabile, male, anal appendages.
Fig. 118. The same, male, sternum of the ninth segment.
Fig. 119. Heiaerina titia, male, anal appendages.
Fig. 120. Lestes elisjinutus, male, second abdominal segment,

from side.

Fig. 121. Heiaerina amcricana, male, .sternum of the ninth seg-

ment.
Fig. 122. Lestes forcipatus, male, second abdominal segment,

lateral view.



Plate; LXVII

111

113 114

120



Plate LXVIII

Anal Append IIgcs of Adults

Fig. 123. Lcsles congener. Fig. 132. Lesies inaequalis.

Fig. 124. Lestes congener. Fig. 133. Lesfex disjunct un.

Fig. 125. Lestes unguiculntus. Fig. 134. Agrion aequahik.

Fig. 126. Lestes nni/uicutntus. Fig. 135. Lestes unaitus.

Fig. 127. Lestes reetiingularis. Fig. 136. Lestes iincatus.

Fig. 128. Lestes rcctanguhiris. Fig. 137. Lestes foreipatus.

Fig. 129. Lestes vigilax. Fig. 138. Lestes foreipatus.

Fig. 130. Lestes vigilax. Fig. 139. Agrion maculatiim.

Fig. 131. Lestes inaequedis. Fig. 139a. Agrion mavuhitum.



Plate LXVIII

128 134
139



Plate LXIX

Thoracic ami Ahdounmil Slniclurcs of Adiilix

Fis'. 140. Arcjia tibialis, female, iiiesostigmal ]ilates.

Fig. 141. Arcjia sedula, female, mesostigmal jtlates.

Fig. 142. Argia violac(<i, female, mesostigmal ])lates.

Fig. 143. Argia fumipciinis, male, anal apiieiulages.

Fig. 144. The .same, male, anal apiiendages.
Fig. 145. Argia violacea, male, anal appendages.
Fig. 146. The same, male, anal appendages.
Fig. 147. Argia apicalis, male, ninth sternum.
Fig. 148. Aryia fttmipennis, female, mesostigmal plates.

Fig. 149. Argia sedida, male, anal appendages.
Fig. 150. The same, male, anal appendages.
Fig. 151. Argia apicalis, male, anal appendages.
Fig. 152. The same, male, anal appendages.
Fig. 153. The same, female, mesostigmal plates.

Fig. 154. Argia moesta putrida, female, mesostigmal plates.

Fig. 155. Argia tibialis, male, anal appendages.
Fig. 156. The same, male, anal appendages.
Fig. 157. Argia moesta putrida, male, anal appendages.
Fig. 158. The same, male, anal api)endages.



Plate LXIX

144 150

146 161
157

146 152 168



Fig.

Fi

Fi

Fi

FiK.

Fi^'

FIk
Fi-
Fit?.

Fig
Fig

Fig.

Fig.

Fig.

Fig
Fig
Fig.

Fi

Fi

Fi
Fig.

Fig.

Fig.

Fig.

Fig

Plate LXX
Tlwriiiic (Dill Alxliniiihiil Stnicturai of Adidl.s

159. Xiliiili iniiit Irene, iiiale, nnal ai)pendages.

ICO. Tlie same, iiialc, anal apix'udages.

161. EiuiUdf/nui lidf/cni, male, anal appendages.
162. The same, male, anal ai>i)endages.

163. laclinurd pitsilii, female, mesostignial i)lates.

164. Anomdldfjrion hdsiatum, female, mesostignial plates.

165. EnitUaymd dspersum, male, ninth sternum.
166. Anomulafjrion luistutmn, male, anal appendages.
167. The same, male, anal appendages.
168. Isclinura vcrticdlis male, anal appendages.
169. Eudlhiynui douhUddiii, male, right superior appen-

dage seen from the left and above.

170. Chrontdgrion condifum, female, mesostigmal plates

and dorsum of prothorax.

171. Ischnura ponitd, male, ninth sternum.
172. Anomeddgrion liastedum, male, ninth sternum.
173. Ischnurd posita, male, anal appendages.
174. Ampludf/riini sducuim, male, anal apjiendages.

175. EiudJdgmd douhJcddifi. male, anal ap])endages.

176. EndUiigmd cdruncididum, male, I'ight sujjei'ior ap-

pendage seen from the left and above.

177. Isclinuni positd, male, anal appendages.
178. AmpliUigrion .•iducium, male, anal appendages.
179. Eudlhigmd civile, male, right superior appendage

seen from the left and above.

180. TscliHurn verticedis, female, mesostigmal jdates.

181. Ampliiitgrion sducium, female, mesostigmal jdates.

182. Ncludennid irene, female, mesostigmal plates.

183. The same, male, ninth alidominal sternum.



Plate LXX

159

.\V
-"^"""^lee 173 177



Plate LXXI

Anal Appendages of Adults

Pig. 184. Isclinura hdlkotti. F
Fig. 185. EnaUagma signafuvi. F
Pig. 186. EnaUagma poUutum. F
Fig. 187. EnaUagma caruncxda- F

turn. P
Pig. 188. EnaUagma aspersum. F
Pig. 189. EnaUagma cbriitm. F
Pig. 190. EnaUagma divagans. F
Fig. 191. Isclinura keUicotfi.

Fig. 192. EnaUagma signatum. F
Pig. 193. EnaUagma poUutmn. F
Fig. 194. EnaUagma caruncula- P

turn. F
Fig. 19.5. EnaUagma aspersum. F
Fig. 196. EnaUagma. ebrium. P
Pig. 197. Emdlagma divagans.

r. 198.

(.199.
r. 200.

f.
201.

^ 202.

',. 203.

',. 204.
r. 205.

J. 206.
r. 207.
r. 208.
r. 209.

;. 210.

' 211.

Emdlagma
Emdlagma
EnaUagma
EnaUagma
EnaUagma
EnaUagma
EnaUagma
EnaUagma
turn.

Emdlagma
EnaUagma
En(dlagma
EnaUagma
EnaUagma
EnaUagma

civile.

traviafum.
calverii.

cyatkigermn.

antennatum.
exsulans.

geminaium.
caruncula-

iraviaium.

calverii.

cyatliigerum.

antennatum.
e.rsulans.

geminaium.



Plate LXXI

204
211



F



Plate LXXII

213

220

221

223

215 224

216

218

219

^225"^

226

^
227



Plate LXXIII

Nymphs

Fig. 217. IscJinura verficalis.

Fig. 222. Agrion maculatiim.
Fig. 228. Lestes forcipaius.



Plate LXXIII

v.-i- tSsX

^:**.^:5»^^

217

«*«^l^;#^
"4'

s,.

wiSEs

I I

«!^'
y/

«Ln-

> %
/ A f N

228