Bulletin STATE OF ILLINOIS DEPARTMENT OF REGISTRATION AND EDUCATION DIVISION OF THE NATURAL HISTORY SURVEY STEPHEN A. FORBES, Chief Vol. XIV. BULLETIN Article III. A Study of the Malarial Mosquitoes of Southern Illinois II. OPERATIONS OF 1920 BY STEWART C. CHANDLER PRINTED BY AUTHORITY OF THE STATE OF ILLINOIS URBANA. ILLINOIS November, 1921 SCHNEPP & BARNES, PRINTERS, SPRINGFIELD, ILL. 52443—1,200 ERRATA Page 44, line 1 of text, for "sludge-worms" read midge larvae, and for "larvae of the midges" read slndge-worms. Page 188, line 4, for 3 read 23. Page 216, last line, for "the opposite page" read page .11 'i. Page 267, delete line 13 from bottom. Page 382, lines 3 and 5 from bottom, for "decrease" read change. Article III. — A Study of the Malarial MosqitUocs of Southern Illi- iiois. II. Operations of ig20.. By Stewart C. Ciiandlek. Introduction The mosquito survey of southern Ilhnois, which was begun by the author in the spring of 1918, has been carried forward during the season of 1920 at Herrin, WilHanison county, and vicinity. The object of the work, as fully explained in a former article of the Natural History Sur- vey Division,* is to locate the places which breed mosquitoes, to point out what types of location are especially favorable to the production of the malaria mosquitoes, and to increase our knowledge of the seasonal occur- rence of all mosquito species to be found in southern Illinois. It is hoped that these articles will provide data of use to citizens of communities in- lerested in a reduction of malarial disease through a control of the mos- c|uitoes transmitting it. It is planned to continue the survey, each year in a different locality typical of some considerable area, so that eventually all types will be covered. Before describing the work of the season, it is well to recall a few fundamental facts about mosquitoes and the relation between them and malaria. It is especially important to remember that some body of water, either temporary or permanent, is necessary to the development of the mosquito. Of the four stages through which this insect passes in its life cycle, egg, larva, pupa, and adult, the first three are entirely aquatic. The adult mosquito lays its eggs upon the surface of the water, or failing to find any water it may die without depositing any eggs. The common wigglers or wiggle-tails which hatch from these eggs pass their existence in the water, feeding on the minute organisms which they find there, until they emerge as adults, this entire process requiring from one to three weeks. The dependence of the malarial organism upon the mosquito needs no discussion here, except merely to state that malaria is transmit- ted to man only through the bite of certain species of mosquitoes belong- ing to the genus Anopheles. These mosquitoes are called the Anopheline or malarial mosquitoes to distinguish them from the Culicine species, which do not carry the disease. Description of the Breeding Places at Herrin The situation at Herrin is typical of much of the mining territory in southern Illinois. The town was started at a point between three coal mines and has spread in all directions up to the edges of the mine prop- erties. Close to each mine two kinds of water are to be found, one in ponds cared for by the mining company and used for boilers and washers, •Article XI. volume i;',. \ Stud.v of the Malarial Mo.squitoes of Southern Illi- nois. I. Operatinn.s of 1 ;i I s ;iiicl l!llii. By Stewart ('. Chandler. 24 and the other the waste water from the mines which is allowed to run off where it will as long as it docs not contaminate the other source. There are a few sink-holes in the west part of Herrin, also characteristic of a mining area because they are jjroljably caused by the sinking of the ground over a part of the mine which has been worked out and aban- doned. Just to the northwest of Herrin is a woods swamp, which in rainy seasons covers an area of about half a scpiare mile. Low, swampy, wooded areas are fairly common in the mining sections of ^^'illiamson and Franklin comities ; and in this case the water in the swamp is kept replenished by waste water from the mines. In going carefully over the town and the territory immediately sur- rounding it I found eight breeding places, or series or types of breeding places—including those I have classed as domestic—from which the mos- quitoes to be found in Herrin might be expected to come. All but the latter class are numerically indicated on the accompanying map, and a brief characterization of all of them follows : 25 Nu. J. An open drain through town, known as llic llth St. ditch. This ditch is fed quite largely by waste water from the mines supplement- ed by small tributaries which carry off the rains and natural surface water. No. 2 ( Fi.g. 1 ). Sink-h(jles to he found in the west part of Herrin. the formation of which has alread\' been descrihcd. Fig. 1. Siiil^-liole, M'cst JU it in ; prtirliM-os \fij' IV-w iiiostiuitoes. Fig 2. Woodbind poul, noi-tli t-iluf <'t' lit-r-iin : m;U:irial niosfjuitoc.^i. piolinc bi-fcder' of 26 No. 3 (Fig. 2). The mine pond at Sunnyside, in the southwest cor- ner of Herrin. No. 4. A series of woodland pools to the northwest along a railroad track, and partially formed by the railroad embankment. This track is a feeder to one of the mines and is much frequented by miners, especially when going to fish in the ponds of that vicinity. No. 5. A woods swamp to the northwest of Herrin, described above. No. 6. Mine ponds north, of Herrin. The main pond, marked A on the map, is used for the boilers and washers, and the other, marked B, is a swampy area overgrown with cattails and fed by waste water from the 17th St. ditch. No. 7. A series of mine ponds to tlie east of town. No. 8. Domestic places, such as tin cans, rain-water barrels, wells, and reservoirs. The Production of Mosquitoes Monthly inspections were made at each of the eight series of breed- ing places, and a record of the abundance of mosquito wigglers was kept. Larvae and pupae were collected and reared to the adult stage in the author's insectary at Carbondale. The species were later determined by Dr. C. P. Alexander, of the Natural History Survey. The determinations of two species supposedly foreign to this region and one new species were corroborated by Dr. Harrison G. Dyar, of the United States Nation- al Museum. The accompanying table (Record of Alosquito-breeding at Herrin, 1920) shows the monthly abundance of mosquitoes, both Anopheline and Culicine, in the eight different breeding places watched during the season. It will be noticed that six terms are used in this table to indicate absence or grades of abundance, namely, none, very few, few, fair numbers, many, and very many. In order to give a numerical value to these rec- ords, none is represented by a cipher (U), very few by 1, few by 2, fair numbers by 3, many by -1, and very many by 5. These figtn-es are inserted in the table at the right of the terms to which they apply, thus making it possible to secure totals convenient for purposes of comparison. The totals for each month show the relative danger, throughout the season, of becoming infected through the bite of the Anopheline mosquitoes; and the totals for each breeding place may be useful in distinguishing the types of places which produce the most mosquitoes. The mosquito pro- duction is shown more clearly by the following diagram in which the breeding-place totals from the table are represented by the heights of the columns, the eight columns representing the eight breeding places. Both the Anopheline and the Culicine mosquito records are shown on the diagram for purposes of comparison. 27 ANOPHELIKE CULICIIHE 12345678 12345678 A mere glance al the table ( p. 5.S ) or the diagram will show that there is a great dilTerence in the breeding ])laces in respect to their pro- duction of mosquitoes during the season. It is very evident that an abundance of Anopheline mosquitoes may be produced in a place in which few Culicine species are bred, and z'icc 'c'crsa. It may be dif^cult to ac- count for these variations in the numbers of mosquitoes produced m ditl:"ercnl situations, but a study of conditions at Herrin may help to dis- tinguish the types of places that are most dangerous. COMPAKISON OF BuEliDI NT, Pl,.\rES No. 1, an open ditch, proved to be of little importance for the pro- duction of malarial mosquitoes, but of considerable importance for the other type. In the main channels of this ditch the waste water from the mines seemed to prevent mosquito develoiJment, and (a very important fact) the edges of the ditch were clean, with little or no overhanging vegetation to furnish protection to the mosquito larvae. Those found were in the small feeders or tributaries ; and in most cases contamination of the water in them by the filth of the street made conditions unfavor- able for Anopheles larvae. No. 2, a series of sink-holes, produced relatively few mosquitoes, either Anopheline or Culicine. Many of the pools dried up wholly or partially, the receding waters leaving edges exjjosed and unprotected, so that predaceous enemies could keep the moscpiito larvae and pupae down U) a mininnim. Nos. 3, 4, 5, and T all contained considerable water, had much grass or weeds along their margins, and appeared to contain enough suitable food for the development of malarial mosquitoes. No. 3 is an especially typical breeding place for them. No. did not seem to be favorable to the production of Anopheline mosquitoes. None of either kind were found in Part B, which contained much waste water from the mines, and but a few in Part A, which from its character might be expected to contain Anoj^heles larvae. No. 8, including all sorts of domestic containers of water, prodiiced no Anojiheline mosquitoes whatever, but was resijonsible for some Culi- 38 m — 29 cines. This corroborates statements made by many observers of mos- quito life, that the malaria-carrying mosquitoes do not by choice breed in water found about the habitations of man. Malaria in Herri n In order to secure a monthly record of the number of cases of malaria in Herrin, the physicians were asked to record their cases on blanks furnished them for that purpose. The monthly summary of their reports is given in the following table. Number of Casks of Malaria in Herrin. 1930 Ph.vsician 30 ably due to hold-over cases, which reappeared as the weather wanned up in spring. May June July Aug. Sept. Oot. Hov, Number of cases of malaria (upper line), and abun- dance of Anopheline mosquitoes (lower line). Species of Mosquitoes at Herrin, 1920 The following table gives the species of mosquitoes reared from col- lections at Herrin, the months when collected, and the numbers of the breeding places in which they were found. For example, the first species listed (Anopheles guttidatiis) was bred from lai'vae or pupae collected in August from breeding places Nos. 4 and ."i, in September from Nos. 4 and 7, and in October from Nos. 5 and 6. Of these eleven species, three are worthy of special notice, namely, Anopheles crucians, Aedcs sollicitans, and Ciilc.v degnstator. The first two are distinctly salt-marsh species, very rarely found more than fifty miles from salt water. Dr. Harrison G. Dyar, who confirmed the determi- nations of these species, expressed great surprise that they were found so far inland, and suggested that there might be some salt deposits or salt springs in the vicinity, creating conditions approximating those of the seacoast. This is entirely possible, as those familiar with the history and geology of southern Illinois are well aware. There is certainly much salt under the surface, from Murphysboro east to the Ohio River, as wit- nessed by the salt springs, salt wells, and old salt works which were at one time of commercial importance, and it is possible that the waste water from the mines is a factor in the production of salt-marsh conditions at Herrin. The last of the three species has been taken before in the Mis- sissippi V'alley. It is a new species, and is to be called Cities dcgustator by Dr. Dyar. Spec IKS of Mosqvitoes reared fro.m Imiiati-re Stage.s,* Herrix, 1920 Species. 32 Further data were obtained this season on the relative abundance of Anopheles gittt Ilia tits and A. punctipcnnis. The fact was brought out in the survey work at Carbondale, reported by the author in the operations of 1918 and 1919, that the former species, considered the more effective carrier of malaria, was outnumbered 12 to 1 by the latter; but at Herrin during the season of 1920. there were exactly as man}' gnttulatiis reared from the monthly collections as punctipcnnis. Conclusion Control measures were discussed in full in the report of the opera- tions of 1918 and 1919, mentioned in the introduction to this article. At Herrin, owing to the necessity of maintaining ponds, drainage—one of the best methods of control—can not be employed. It is quite likely that cleaning the edges, stocking the pond with fish ( especially with top-min- now), or applying oil in some way. will be found to be the most practical methods.