Bulletin


ST A TE OF ILLINOIS 

DEPARTMENT OF REGISTRATION AND EDUCATION 

DIVISION OF THE 
NATURAL HISTORY SURVEY 

STEPHEN A. FORBES. Chief 

BULLETIN Article XI. 

AStudy of the Malarial Mosquitoes 

of Southern Illinois 

I. OPERATIONS OF 1918 AND 1919 

BY 


STEWART C. CHANDLER 


PRINTED BY AUTHORITY OF THE STATE OF ILLINOIS 

URBANA. ILLINOIS 

July. 1920 



ERRATA
Page 97, line 17, for first larval read puital.

Page 112, in legend, for jonessi read jonesii.

Page 114, in legend, for or read of.

Page 125, line 4, for Bonosa read Bonasa.

Page 131, in legend, for Jiirundinaceus read hirudinaceus.

Page 138, last line, for coccoon read cocoon.

Plate XII, explanation page, next to last line, for acrivora read aerivora.

Plate XIII, explanation page, next to last line, for WMte-gruhs read White-gruh.

Page 293, Figure 5a was reversed in printing, and the two items of the legend

should change places.

Page 515, second table, for Pelocoris femorata read Pelocoris femoratus.



Article XI.

—

A Study of the Malarial Mosquitoes of Southern Illi-

nois. I. Operations of 1918 and 1919. By Stewart C. Chandler.

Introduction

The Relation of Mosquitoes to Malaria.—The part which mosquitoes

play in the transmission of malaria was established years ago, but we often

find people who never heard of the relation between the two. It is there-

fore important to make clear, at the beginning of this report on mosqui-

toes, the facts in the case. Malaria was at first thought to be carried to

men by damp night air. "Mal-aria," bad air, was the name given to the

disease for that reason. It was later clearly established that mosquitoes

breeding in the swamps and other damp places and biting at dusk are

the sole carriers of the disease. A mosquito, upon biting a malaria pa-

tient in whom the disease parasites have developed for about ten days,

sucks up the parasites into her mouth. Only the female mosquito bites

and is capable of transmitting the disease. The germs now develop for

a period of eight to ten days. In this time they break through the lining

of the stomach wall and get into the salivary glands, from which they are

readily transferred to man by the bite of the mosquito. Not all Isinds

of mosquitoes are malaria carriers. Only three species in this country
(all belonging to the genus Anopheles) are implicated. There are in all

twenty-four species of mosquitoes regional in Illinois.

Malaria in Southern Illinois.—Illinois is not usually regarded as a

state in which malaria is common ; and the northern two-thirds would
not be so classed. Southern Illinois, however, has a reputation not so

enviable. I have found it impossible to secure correct statistics on the

extent of malarial disease. Most physicians whom I have consulted do
not keep records of malaria such that they can say definitely how many
cases they have treated in a year's time. They report irregularly or not

at all on this disease to the State Board of Health. Estimates, of course,

can be secured from them, and I have always found physicians whom
I have consulted very willing to make as careful estimates as possible.

Taking as examples the two towns in which I have done most of my sur-

vey work, Carbondale and Murphysboro, I found that the estimates gave
Carbondale from a hundred and fifty to two hundred cases of malaria
in an average year, and Murphysboro from two hundred to four hun-
dred cases. As these are towns of six and eight thousand population,

respectively, we find that from two to five out of every hundred men,
women, and children are attacked by malaria each year. There are many
other points in southern Illinois, especially along the Mississippi, Wabash,
and Ohio rivers, which are greater malaria centers than the towns men-



308

tioned, but estimates from these places are so widely divergent that I am
not presenting them at this point. The State Board of Health estimated,

for the period of 1909 to 1914, (Vol. II, No. 6 of Illinois Health News,)

that in ten of our southern Illinois counties at least 8 per cent, of the

population was ill from malaria each year. They put the number of

cases for the state at nineteen thousand per annum, and the number

of deaths from malaria at ninety-five per annum. Most of the physi-

cians whom I consulted said that deaths from this cause are becoming

increasingly rare, because of increased drainage in some sections and the

fact that most people now understand the value of quinine and more

of them than formerly screen their houses. The State Board of Health,

in an endeavor to assign a money loss attributable to the disease in the

state, estimates that the average loss to the individual patient due to med-

ical attendance, cost of remedies, and diminished earning power is

$160.00, amounting to over three million dollars for the nineteen thou-

sand cases. There is another form of loss which is not always taken into

account in speaking of a disease, namely, loss of vitality. Very often

the patient is able to work, but only with a greatly decreased vigor,

resulting in a loss, if not to the worker, at least to his employer. This

reduction of efficiency is recognized in southern Illinois especially by big

corporations, like the railroads, which have large numbers of employees.

Object of the Survey.—It was in view of facts of this nature that

the Southern Illinois Medical Society passed a resolution in the fall of

1917 requesting the State Natural History Survey to make a mosquito

survey of southern Illinois in order to locate the breeding-places of

malarial mosquitoes, with a view to eventual efforts for the control of

the insects and the prevention of malarial disease. This work has been

carried on during the seasons of 1918 and 1919 as continuously as was
consistent with the press of other duties. It was thought best to limit

the work to one or two towns chosen as typical rather than to attempt to

cover a large territory more superficially.

It has been the main object of the survey to find the kinds of places in

which malarial mosquitoes breed in southern Illinois and to learn which
kinds are clearly preferred and how continuously and to what extent the

various species abound through the year. From these data, together with
those obtained from physicians, certain conclusions have been drawn
in respect to the relation between the amount of malarial disease on
the one hand and the number of malarial mosquitoes, the proximity of
their breeding-areas, and the distances to which they are capable of fly-

ing, on the other.

Life History.—A brief account of the life history of the mosquitoes
will aid those not familiar with their habits to appreciate the importance
of a knowledge of their breeding-places.

In spring adult mosquitoes appear as the weather warms up, some
as early as March in southern Illinois. The eggs are laid on some body
of water, temporary or permanent, large or small. If the female finds



309

no water, she may die without reproducing, a fact to be borne in mind
when control measures are considered. At least a day is necessary to

bring the eggs to hatching—considerably more in late fall or early spring.

The larval mosquitoes, commonly known as wigglers, are seen swimming
in ponds, creeks, and other breeding-places, or floating at the surface,

which they must visit at frequent intervals for a supply of air. They
feed upon minute aquatic plants and animals. The larval period

varies from one to three weeks, according to season and tempera-

ture. In the pupal stage, which is passed in the water and lasts from one

to five or more days, the head and thorax are much larger than in the

larva. The length of the entire life cycle depends on the time of year

and the species. It is from ten to twenty-five days, being generally a

little longer in the genus Anopheles, to which the malaria-carrying mos-
quitoes belong, than in other genera. One authority* (Howard Dyar,

and Knab) gives twelve to twenty-four days as the total length in May
and June for the Anopheles in Washington, D. C. In planning the treat-

ment of breeding-places, we must remember that the entire life cycle of

the mosquito may be passed in ten days, and that successive generations

will be produced as long as warm weather continues and breeding-places

are available. The stage of hibernation varies with the species, but it is

fairly well established that of Anopheles only the females survive the

winter. I have found these during the winter at Carbondale in cellars,

culverts, and other sheltered places.

Survey Work at Carbondale

Frequency of Malarial Disease.—Four physicians who had practiced

for many years in Carbondale, gave the following estimates of the num-
ber of cases of malaria treated in the town in an average year: Dr. J.

W. Barrow, 200 ; Dr. Roscoe Lewis, several hundred ; Dr. W. A. Bran-
don, 150 ; and Dr. H. C. Mitchell, 150. As the population of the town
is about six thousand, it would appear that at least two or three out of

every hundred are treated for malaria each year.

Mapping the Territory.—A map of Carbondale township^—not re-

produced in this report—was traced, on which I indicated most of the

possible breeding-places of mosquitoes. It was my first intention to

make examinations in the country as well as the town, and I designated
on this map about twenty-five tributaries and feeders of Crab Orchard
Creek, a stream about two miles east of Carbondale. The doctors

whom I interviewed had told me of the continued occurrence of

malaria among the farmers along this creek and I later found malarial

mosquitoes breeding in these tributaries. Lack of time compelled me,
however, to confine my attention to the town and immediate surroundings.
The breeding-places were numbered in my notes and on the map for ease

in recording findings. Larger maps of Carbondale and vicinity were

• "The Mosquitoes of North and Central America."



310

obtained from the Illinois Central Railway division office through the

courtesy of Supt. W. Atwill, and from Mr. C. E. Cox, a former civil

engineer. By means of these larger-scale maps I was able to- indicate

practically every possible breeding-place of mosquitoes which would be
likely to affect the people of Carbondale. Although winds may carry mos-
quitoes for a distance of several miles (as will later be shown in the case
of Anna and Jonesboro) it is usually believed that mosquitoes do not fly

over half a mile from their breeding-places. Most of the places ex-

amined are within half a mile of the edges of town. (Maps, pp. 312, 313.)

Examinations and Collections.—Collections of larvae and pupae were
made once, and sometimes twice, a month during the breeding seasons of

1918 and 1919 (with the exception of September, 1919) and were bred
to the adult for identification. The wigglers were scooped up with a
small strainer with a handle and a screen of about twenty meshes to the

inch. They were removed with a small soft brush, such as is used in

water-color work, and put temporarily into tin pill-boxes together with
a little of the same water in which they were found. The contents of

the pill-boxes were later emptied into glass jars in the insectary and more
water with aquatic vegetation and some of the mud from the bottom was
poured into the jars to furnish food and natural conditions. I usually

secured this water from some one or two breeding-places which seemed
to produce mosquitoes abundantly, taking care to exclude mosquito larvae

and any animals which might be predaceous upon the mosquitoes. Notes
were made as to the pres«ice and abundance of the malarial and non-

malarial mosquitoes in each breeding-place examined, and the species

were later determined by Dr. C. P. Alexander and Mr. J. R. Malloch,

of the Natural History Survey.

The Anopheline and Culicine larvae (carriers and non-carriers of

malaria) are readily distinguished by the positions which they take while

resting at the surface of the water, the Anophelines lying parallel to the

surface while the Culicine larvae hang down at an angle of about forty-

five degrees, with only their long breathing tubes touching the surface.

The pupae are more difficult to distinguish and will not be discussed.

The adults of our Anopheles are easily distinguished from Culex and
other genera by the spots on the wings, the Culicine wing being clear.

The palpi of the female are longer in Anopheles than in Culex. The body
of the Anopheline adult forms an angle with the surface upon which it

rests, while that of the Culicine is parallel to the surface.

BREEDING-PLACES

Mosquito breeding-places at Carbondale are typical of those in many
other towns. In the following description I am grouping them in classes

which will be readily recognized by residents of other places. The breed-

ing-places were numbered, as shown on the maps (pp. 312-313), to facili-

tate the making of records. Plates XXXI—XXXV illustrate a few of

the situations.



311

Class I, Swamps.—The swamps studied are of a type common in the

southern end of the state. Most of them are grown up to cattail, the

density of which will be realized by reference to Fig. 1 and 2. The
water generally contains a great deal of decayed organic matter. Around
the edges usually, and in the main channels (if there are any), the water
is clearer. At Carbondale the railroad shops, round-house, and yards
are in a series of these swamps ( Nos. 54-57, 59, fJl). The physicians

in town have all spoken to me of the large number of cases of malaria

among the railroad men, and I do not doubt that these swamps are partly

responsible.

Class II, Marshes.—-A marsh, as the term is here used, is not as

deep as a swamp, does not contain so much organic matter, and con-

tains a considerable growth of grass besides some cattails. In Carbon-
dale such a place (No. 71) is found opposite the old cemetery near the

negro school. This place (Fig. 3) produced many malarial mosquitoes.

Class III, Ponds.—The ponds at Carbondale are -small bodies of

water artificially formed. No. 58* in the A. & L. Tie Company's yards

and their two "creosote lakes" (Nos. 6G and 67), No. 52 on Chestnut

street, No. 45 east of Freeman street, and the pond on the campus of the

State Normal School (No. 179) are examples. The growth in these

ponds varies from none at all, as in the Tie Plant property, to that of a

swamp.
Class IV, Roadside Ditches.—Especially along built roads there are

often left ditches which contain water and are grown up to grass or cat-

tail. Numbers 62 and 63*, near the Illinois Central yard office, are types.

Many other ditches show no growth at all and, as will afterwards be

shown, yield comparatively small numbers of mosquitoes.

Class V, Creeks and Streams.—Crab Orchard Creek and its tribu-

taries, Pyles Fork and a creek (No. 53) running into the swamps north

of town, are those which I watched most closely.

Class VI, Open Drains through Toivns (Fig. 4, 5, 6, 7).—These

drains may originally have been natural streams, but in the case of the

two watched at Carbondale (Nos. 47 and 48), their courses have been

somewhat altered.

Class VII, Lfl/fe«.—Thompson's Lake (No. 51, Table A) at the south

edge of town is leased by the Country Club and is consequently much
visited by many of the residents. It is also important because of its

proximity to town.

Mosquito-producing Factors of Various Types.—While all of these

kinds of breeding-places yielded Anopheles, it .soon became apparent that

some were much more productive than others.

The cattail swamps might be supposed, from their large area, to breed

more malarial mosquitoes than any other waters, and they are no doubt

important, although they present certain features which seem to decrease

the output. I have found some of them yielding these mosquitoes in

" • No. missing on map. [Continued on p. 317.]



3
1
2



3
1
3



3
1
4



3
1
5

o
o
o

c
e
c
c

c
c

c
.
2

5
.
2
.
2

.
2

°
.
2

c
a
c
c

B
c

c

I
|
B
|

a
s

I

I
I
I
I

I
q
I

I

O
J
"
S
o
o

i
j

e
c
u

c
s

l
l
>

I
S

S
a

"
"
*
a
S

3

e
s
£
c
a

§
;

z
z
'
s

Z
Z
Z

Z
J

s
e
c

5
B
S

t
,

r
t

r
t

S
o

<
Z

a
S
S

l
&
S

S
C
L
C
S

S
o

I
-
)



3
1
6



317

every month of the season, but not in numbers corresponding to their

area. The large amount of organic matter which they contain seems to

be detrimental to Anopheles larvae. At one time during a summer drouth
the common duckweed (Lemna minor) completely covered the surface
of a part of the swamp where cattails were absent, and I could find no
mosquito larvae around the edges of this area.

The marshes (Class II) seem to produce more Anopheles than the
swamps, probably because of a more favorable vegetation, as already
noted.

Ponds (Class III) are dangerous if they contain sufficient vegeta-

tion to give shelter and protection to mosquito larvae. Grass, reeds,

rushes, and cattails favor their escape from small fishes and predaceous
insects. I was never able to find any mosquitoes breeding in Pond No.
58, in the' Tie Plant yard, or in the "creosote lakes," the latter probably be-

cause of the cresote waste emptied into them. No breeding was found in

No. 53 and very little in No. 45. The three Tie Plant ponds and No. 53
have no vegetation along the edges to furnish protection. No. 45 showed
a growth of water-lilies which did furnish some protection, although
not as efl^ective as grass. The pond on the Normal campus (No. 1?9;
Fig. 8 and 9) has a good deal of plant growth along the edges, and I

found some Anopheles breeding there practically every time I looked for

them. As some of this vegetation was cut down in the fall of 1918, it was
not quite so abundant in 1919 as the year before, and Anopheles were also

less abundant. Several physicians have spoken to me of the number of

cases of malaria in the Normal dormitory, and I found Anopheles breed-

ing within twenty feet of it (Fig. 8).

Roadside ditches (Class IV) generally contain less water than the

other types, but they are likely to be mosquito breeders unless they dry up.

Some of them, however, have no vegetation whatever and usually con-

tain few or no wigglers. Numbers 62 and 63, by the Illinois Central yard
office, lined with overhanging grass and filled with other vegetation, hold

their water well through the season and furnish quite ideal conditions

for Anopheles.

In creeks and streams (Class V) mosquito breeding is limited not

only by vegetation and water supply, but also by strength of current and
purity of water. In the main stream of Crab Orchard and Sycamore
creeks and of Pyles Fork I found very little or no breeding except when,
as in the case of Pyles Fork, dry weather reduced the stream to a series

of pools. In the backwaters and in small tributaries with little current,

Anopheles were often quite abundant. Small streams with little current,

such as No. 53, running into the swamps, especially those with grassy
banks,* may be prolific breeders. When waste water of any kind pollutes

the stream it is likely to reduce mosquito production.

Practically the same may be said of Class VI (open drains) as of

creeks and streams. They are, perhaps, more likely to become polluted

See Fig-. 12—a stream at Murphysboro.



318

by garbage or through sewer leaks, in which case I have noticed that the

production of malarial mosquitoes is much more reduced than that of the

non-malarial species. Where drains are left with weedy edges, as in Car-

bondale, they are a serious menace to the health of the town. Figures

4 to 6 show the ideal breeding conditions which these drains afTord, and

records of physicians show frequent cases of malaria in houses situated

close to them. Fig. 6 shows the proximity of one ditch to a city school

building.

The Thompson's Lake (Fig. 10) type of breeding-place is dangerous,

providing there is sufficient protective growth along the edge to mask
wave action, since this seems to be detrimental to the development of

mosquito larvae. I am inclined to think, however, from the past season's

experience, that Anopheles larvae prefer shallower water than is found

even along edges of this lake, and that consequently it is not as important

as some other breeding-places before mentioned. However, I found at

least a few Anopheles upon practically every visit, and as there is a long

shore-line the lake must have some effect on the amount of malaria.

Prevalence of Mosquitoes and Abundance of Malaria.—In the fol-

lowing table I am showing the presence and abundance of the mosquito

larvae in the breeding-places which I was able to watch fairly continu-

ously throughout the year. The six terms used to indicate the numbers

of Anopheles—none, very few, few, moderate numbers, many, and very

many—are given grades of 0, 1, 2, 3, 4, and 5, respectively, and the data

for each month are figured separately, the records for the two years be-

ing combined. This table shows for each month the number of visits at

which each of the six grades of abundance was found, the average abun-

dance per visit for each month, and, in the lowest line of the table, the per-

centages of abundance, taking the highest grade (very many) as the base

of the computation. In April, for example, the average abundance of

larvae of malarial mosquitoes was 2.7 per cent, of "very many;" in May
this average was 30.8 per cent. ; in June, 67 ; and so on.

It was found impossible to obtain accurate figures on the prevalence

of malaria in Carbondale, but from the medical record of the Illinois

Central Railroad employees in town, kept by Dr. H. C. Mitchell, division

surgeon, it is evident that the increase and decrease of the number of

cases of malaria are closely correlated with the abundance and scarcity

of the Anopheles mosquitoes.

Species.—The accompanying table (C) contains a list of the species

of mosquitoes which were either taken as adults, or bred to the adult stage

from larvae and pupae, during the last two seasons. It also shows the

types of breeding-places in which they were found and the months in

which the collections were made. The numbers used are those of the fore-

going description of types, viz. : Class I, cattail swamps ; Class II, marsh

;

Class III, ponds ; Class IV, roadside ditches ; Class V, streams ; Class VI,

open drains ; Class VII, lakes.



3
1
9



3
2
0



331

RELATIVE ABUNDANCE OF MALARIAL MOSQUITOES, CARBONDALE, 1919

A number of writers have raised a question as to the comparative
importance of Anopheles gnttwlahis and A. pimctipennis as carriers of

malarial disease, it being believed by some that guttulatus is the more
active carrier. The preponderance of pimctipennis in my records indi-

cates that this can hardly be the case. In 1918 guttulatus was taken in

only four different collections during the year, while pimctipennis was
taken in nineteen. In 1919 seventy-six adults were obtained at Carbon-
dale and only six were guttulatus. Guttulatus being so rare in Carbon-
dale, I think the other species must be held responsible for most of the

malaria present.

Mr. H. R. Carter and associates, of the U. S. Public Health Ser-

vice,* report that they found guttulatus predominating in Alabama and
South Carolina in their August and September surveys, and punctipennis

in spring to June 15 and in fall. They qualify this, however, by say-

ing that in August and September the live water contains most of the

punctipennis and the bayou water the guttulatus. The following table

shows the relative numbers of adults of each species collected in Carbon-
dale from May to October, 1919.

A. guttulatus...

A. punctipennis.

May



322

wintered eggs; but this may be due to the fact that summers are drier,

and favorable pools rarer, than they are in the North."

Survey Work in Murphysboro

My procedure in Murphysboro was similar to that at Carbondale.

The leading physicians vvhom I interviewed gave two hundred to four

hundred cases of malaria as their estimate for an average year. As the

population is about eight thousand, this would mean that 2J^ to 5 per

cent, of the inhabitants are treated for malaria annually. A map of the

township was traced, and all possible breeding-places were located ; and

examinations and collections were made, but, owing to other occupations,

not very continuously throughout the season.

BREEDING-PLACES

Class I, Cattail Sivamps.—No breeding-places of this type are near

enough' to affect Murphysboro. A large number which are in some re-

spects similar, I am placing in a separate class (No. IX).

Class II, Marsh.—Not found in Murphysboro or immediate vicinity.

Class III, Ponds.—Railroad embankments very often form ponds by

damming up water. One such pond, located close to the Brown shoe fac-

tory, I found to be a breeder of Anopheles. Pleasure and amusement
parks may be mosquito-breeding grounds ; and a few small ponds in the

city park in Murphysboro contain Anopheles. In a ravine very close to

the high school is a representative of this type (Fig. 11).

Class IV, Roadside Ditches.—This type is not noticeable in Murphys-
boro.

Class V, Streams.-—Running through the city park is a slow stream
(Fig. 12) with banks well covered with grass and affording ideal breeding

conditions for Anopheles mosquitoes. The fact that the only park in

town includes this stream is deplorable, as it probably accounts for much
of the malaria. It should be remembered that a park is very often vis-

ited for picnics in the evening, when malarial mosquitoes bite.

Class VI, Open Drains.—One drain in the north end of town is re-

, sponsible for the production of part of the Anopheles mosquitoes in

Murphysboro.

Class VII, Lakes.—The situation at Carbon Lake, belonging to the

Country Club of Murphysboro, is very similar to that at Thompson's Lake
near Carbondale. Stecher's Lake is much more likely to breed Anopheles,
especially because of its grassy edge (Fig. 13). Under the culvert at

one end of the lake I was often able to make large collections of Anopheles
adults.

Class VIII, Temporary Flooded Land.—This type is caused by over-
flow of the flats of the Big Muddy River, at the south edge of town. The
high water lasts, however, for so short a time that I doubt whether many
of the mosquitoes of Murphysboro can be traced to this source.



3
2
3



324

Class IX, Sink-holes.—The last permanent type is composed of breed-

ing-places caused by the sinking of the ground over abandoned coal mines

after the props have rotted down. These sink-holes fill with water, and
grass and cattails spring up around the edges and sometimes in the center

of the pond. Fig. 14 shows one of them. Fig. 15 was taken during the

drouth of midsummer, 1919, when the water was everywhere very low.

In many sink-holes the water-line had receded so far from the cattail

growth that no protection was left for the mosquito larvae. As a conse-

quence of this and of the concentration of predaceous insects and ani-

mals, there were practically no mosquito larvae in such situations. The
significance of this fact will be brought out later under a discussion of

control measures. The accompanying map shows the remarkably large

number of these sink-holes (eighty in all) just north of Murphysboro. A
considerable number are to be found in the vicinity of the Mobile and
Ohio Railroad shops and yards, and Dr. O. B. Ormsby, of Murphysboro,
told me that a rather high percentage of the railroad cases in town were
malarial. While my work here could not be made continuous enough
to warrant definite statements, these sink-holes are at least probably partly

responsible for this condition.

Survey Work in Anna and Jonesboro

Two days in August, 1918, were spent in survey work at Anna and
Jonesboro. Previous inquiries as to the average number of malaria cases

per year brought surprisingly different replies, as follows : for Jonesboro,

300, 2,000, 50; for Anna, 2,000, 1,500, 150, 600. Only one of these physi-

cians makes the blood tests, and this may account for the widely dilTerent

estimates, as this is the only method of certain diagnosis. He estimated

600 cases in Anna. One of the oldest doctors there told me that most
physicians believe that there is likely to be some malaria in every case

they are called upon to treat.

Breeding-places.—A majority of the physicians and of other citizens

interviewed expressed the opinion that most of the malarial mosquitoes in

the two towns were bred in the bottom-lands of the Mississippi, and I

think that this is a source of a part of them. It is a matter of common
knowledge in Anna and Jonesboro that when the wind blows steadily

from the west and southwest for about two days, swarms of mosquitoes
are carried in from the lakes and sloughs in the bottoms. These inva-

sions are always followed, the doctors all told me, by a marked increase

in the number of malaria cases. The fact that the nearest of these bot-

tom-land breeding-places is six miles from town will serve to show the

distance which mosquitoes may be carried by the wind. It also appears
to be a matter of common knowledge that since the recent drainage of

many of the sloughs and lakes, the severity of these periodic attacks by
mosquitoes has been greatly lessened. It should be remembered that many
residents of Anna and Jonesboro go to the Mississippi bottoms to fish



325

and hunt, or to look after their farms, and that they may thus contract

malaria away from the towns.
There are. however, other much closer, and probably more impor-

tant sources of malaria. In both Anna and Jonesboro small streams run-

ning in and close to town contained Anopheles in considerable numbers,

and I do not doubt that these are among the chief sources of mosquitoes.

Ponds in the fair-grounds of both towns and two other small pools exam-
ined, also showed Anopheles, and it is quite likely that such places furnish

most of the mosquitoes in the vicinity.

Survey Work .\t Scott Field, Belleville

Upon request of Captain Bayliss, principal medical officer at Scott

Aviation Field, investigations of the mosquito situation around the camp
were made in the summer of 1918. This field has been located very close

to a large swamp, which at one point was only a quarter of a mile away.

There was an abundant growth of vegetation to shelter mosquito larvae,

and those of Anopheles were found in considerable numbers. The ordi-

nary swamp-land growth (Fig, 16) of trees, brush, and weeds was quite

rank, and arrowhead especially abundant. Owing to an excessively dry

summer the swamp practically dried up later, and no further examina-
tions of it were made.

Within a few rods of the field boundary is a slow stream (Fig. 17).

This was breeding Anopheles, and they were even more abundant a little

later when the stream was reduced by the drouth to a series of pools.

There was no current at that time to hinder development, and there was
grass enough around the edges for protection.

Scouting Work ix other Pl.\ces

General scouting work was done in and around Thebes and Cairo,

and in Williamson county, and additional types of breeding-places were
observed in these places. Some inquiries were made as to the extent of

malaria, and some maps were made.

Control Measures

1. Drainage.—Beyond a doubt, drainage is the most effective meas-
ure for the control of mosquitoes, with the exception of those living in

running streams ; and the first step in a clean-up campaign is the elimina-

tion of standing water.

At Carbondale a special efifort was made to bring this subject to

the attention of those in charge of property containing standing water.

The opinion of the surveyors that the cattail swamps north of town could

be drained into a tributary of Crab Orchard Creek by a ditch a little over

a quarter of a mile long was laid before the division superintendent of the

Illinois Central Railroad Company at Carbondale.



336

The presence of Anopheles in the pond at the Normal School was
brought to the attention of the president, and the subject of drainage was
broached. Objection was made that the water might be needed in case

of fire, and I then suggested cleaning the edges of the pond as the next

most efficient measure of control.

The importance of draining the marsh near the negro school was im-

pressed upon the president of the city Board of Health, and he took the

matter up with the City Commissioners.

2. Cleaning the Edges of Breeding-places.—Where drainage is im-
practicable, the next most effective means is cleaning the edges of pro-

tective vegetation. While some species of mosquitoes do not seem to

care particularly for shade and protection, those of the genus Anopheles
do, and thrive much better in it. Insects, small fish, and other animals

which prey upon mosquitoes, have a much better opportunity to find and
catch the wigglers when the protecting growth is removed. That they may
often be exterminated by such means I am satisfied from the examina-
tions of the Murphysboro sink-holes in the dry months of 1918 already

referred to and illustrated in Fig. 15. As has been suggested, this method
is especially useful with small streams, which of course can not be drained,

and on which the use of the third remedy (oiling) is difficult. Open drains

through town, which are not at all uncommon in southern Illinois, if

they can not be replaced by covered drains, should at least be carefully

cleaned. They should be covered, if possible, as this both removes pro-

tection and usually prevents the laying of eggs. If drains must be left

open through town their beds should be so graded that the water will not

form pools in dry weather.

A special efifort was made in Carbondale to advise the city author-

,

ities on this subject through the Board of Health, and during Health Pro-

motion Week illustrated talks were made by the writer on the local sit-

uation and all phases of control. It should be remembered that the edges

of a pond or ditch should not be cleaned just once, and then left for the

plants to grow up again, but that they should be kept clean continuously.

Neglect of this precaution was illustrated in Thompson's Lake when it

was lowered eight feet to destroy a growth of- pond-lilies and cattails

troublesome in boating. Much of the growth was killed, but so many
plants grew up again that Anopheles bred almost as abundantly as before.

3. Oiling.—Oiling may be used to smother the mosquito larvae in

the water, in conjunction with cleaning operations. The surface film thus

formed prevents the larvae and pupae from reaching the air necessary to

their respiration. A rate of application commonly recommended is an
ounce of oil to fifteen square feet of water surface. Prof. W,. B. Herms,
of California, finds that application of oil by the dipperful is very waste-

ful and uses a knapsack sprayer instead. Flowing streams may be oiled

by means of drip cans so arranged that oil will drip from them at a rate

of about twenty drops a minute. A mixture of kerosene with a heavy
fuel oil, half and half, is better than pure kerosene, because it spreads



327

well, is lasting, and resists the wind, while kerosene alone is easily blown

aside. Oiling should be done every twelve days during the heat of the

summer, but less frequently in spring and fall, according to temperature,

which determines the rate of mosquito development. However, if it is

desired to control other mosquitoes than the malaria carriers, an applica-

tion once a week is necessary. Vegetation should first be removed, if pos-

sible, from the edges of the breeding-places, because it prevents the main-

tenance of a perfect film. Especially when a wind blows the plants back

and forth, the surface film can not be kept unbroken.

4. The Use of Larvicidcs.—A larvicide as used in mosquito control

is a chemical put into the water and which mixes thoroughly with it to

kill the larvae. It has been found satisfactory in some situations, espe-

cially in yellow-fever control work in the Canal Zone. The larvicide most

commonly recommended is one tested out by the Ancon Hospital Board

of Health Laboratory in 1911. The stock solution is made as follows :*

"150 gallons of carbolic acid is heated in a tank to 312° F. Then 150

pounds of powdered or finely broken resin is poured in. Thirty pounds

of caustic soda are then added, and the solution is kept at the same tem-

perature until a perfectly dark emulsion without sediment is formed, con-

stantly stirring after the resin is put in. One part of the emulsion to ten

thousand of water is said to kill the larvae in less than one half hour, and

one part to five thousand in five to ten minutes."

5. Screening.—Screening houses to keep out mosquitoes is very com-
mon, yet there are many houses, especially in the country, which are not

protected by screens, and too frequently those used are torn, or do not fit

tightly, really acting as traps, allowing the mosquitoes to get into the

house but providing no exit which can be readily found. The malarial

mosquitoes begin to bite at dusk, and if one keeps inside of a properly

screened house in the evening, he is quite safe.

6. Fumigation.—Fumigation is of some value when mosquitoes get

into a house or tent. In such cases burning powdered sulphur or a heap
of pyrethrum powder should clear them out. Cresol, about four ounces
to a thousand cubic feet of space, heated in a shallow vessel until vapor-

ized, is often recommended.
7. Use of Palliatives on Mosquito Bites.—Those who are especially

sensitive to mosquito bites will profit by recent experiments of Dr. H. E.

Ewing.* He found rubbing helpful in diffusing the poison. Although
it increased the itching at first it presently caused it to cease. Strong
alcohol and strong ammonia were more useful than dilute alcohol, dilute

ammonia, soap, or bay rum.

Summary

1. Malarial disease is common in southern Illinois, causing some
loss of life and a large loss of time and money.

• Farmers' Bull. 444. U. S. Dept. Agr.
• "The Use of Palliatives for Mosquito Bites," Journ. Econ. Ent., Vol. XI.

pp. 401-404.



328'

2. Malaria is transmitted from man to man only by the bite of

certain kinds of mosquitoes, which are common in the southern part

of the state.

3. The larvae of these mosquitoes are found in all kinds of waters,

but are most abundant in a fairly clean still water with an abundance of

grass and weeds for their protection.

4. Control measures are (1) the drainage of breeding-places; (2)

keeping the margins clear of vegetation; (3) maintaining a film of oil

upon the water; (4) the use of larvicides for killing the larvae; and (5)

the screening of houses. Additional, but much inferior, measures are

(6) the fumigation of rooms to destroy adult mosquitoes ; and (7) the use

of repellents to drive them away. Palliatives may be used to diminish the

effect of their bites.



Plate XXXI

Fig. 1. Portion of cattail swamp.

-j,^5S»i*

^W':t

I

Fig. 2. Near vii \v .. f . itt i



Plate XXXII

Fig. 3. Marsh ; grass and weeds predominating'.

Fig. 4. Open drain tlirougli Carbondale. Prolific breeder of malarial mosquitoes.



P
l
a
t
e
X
X
X
I
I
I



P
l
a
t
e
X
X
X
I
V

H



Plate XXXV



P
l
a
t
e
X
X
X
V
I

1
4



Plate XXXVII

Pig. 13. Stecher's Lake, Murphysboro. The source of many of the malarial
mosquitoes of the town.



Plate XXXVIII

Fig. 15. Sink-hole in vei'y dry weather. Edges clear of protecting vegetation.

Fig. 16. Swamp at Scott Aviation Field, near Belleville.



Plate XXXIX