STATE OF ILLINOIS DEPARTMENTOF REGISTRATIONAND EDUCATION NATURAL HISTORY SURVEY DIVISION A SYNOPSIS OF THE MOSQUITOES OF ILLINOIS (Diptera,Culicidae) Herbert H. Ross Willbm R. Horsf•,11 IllinoisNatural History Survey BiologicalNotes No. 52 Urbana,Illinois March, 1965 CONTENTS DIAGNOSISOF MOSQUITOES.................... 4 KEYS TO CULICIDAE LARVAE .................... 25 KEY TO CULICIDAE AND CHAOBORIDAE........... 4 Key to Generaof Culicidae(Larvae) .......... 26 Adults (Both Sexes) ....................... 4 Key to Speciesof Aedes(Larvae) ............. 29 Larvae ................................... 5 Key to Speciesof Anopheles(Larvae) ......... 37 LIST OF INCLUDED SPECIES ...................... 5 Key to Speciesof Culex (Larvae)............. 39 KEY TO SEXES OF CULICIDAE ADULTS ............. 5 Key to Speciesof Cullseta(Larvae) ........... 40 Key to Speciesof Orthopodomyia(Larvae) ..... 43 KEYS TO CULICIDAE FEMALES .................. 5 Key to Speciesof Psorophora(Larvae) ......... 43 Key to Generaof Culicidae(Females) ......... 6 KEYS TO CULICIDAE EGGS...................... 44 Key to Speciesof aledes(Females) ............ 8 Key to Generaof Culicidae(Eggs) ............. 44 Key to Speciesof alnopheles(Females) ........ 12 Key to Speciesof Aedes(Eggs) ............... 45 Key to Speciesof Culex(Females) ............ 13 Key to Speciesof Psorophora(Eggs) .......... 47 Key to Speciesof Cullseta(Females) .......... 14 Key to Speciesof Orthopodomyia(Females) .... 14 MOSQUITOESAND DISEASE..................... 48 Key to Speciesof Psorophora(Females) ....... 14 ACKNOWLEDGMENTS.......................... 49 KEYS TO CULICIDAEMALES ..................... 14 SELECTEDREFERENCES ........................ 49 Key to Generaof Culicidae(Males) .......... 15 LITERATURECITED IN THE ILLUSTRATIONS........ 49 Key to Speciesof Aedes(Males) ............. 16 INDEX ...................................... 50 Key to Speciesof Anopheles(Males) .......... 22 Key to Speciesof Culex(Males) .............. 22 COVERDRAWING.--One of the largest Illinois mosquitoesis the "gallinipper,"Psorophora ciliata, which may attain a wing- Key to Speciesof Culiseta(Males) ............ 24 spreadof 15 mm (overhalf an inch). It is a viciousbiter and Key to Speciesof Orthopodomyia(Males) ...... 24 is widelydistributed over Illinois. The larvaeor wrigglersof this speciesbreed in rainpools and have the habit of feedingon larvae Key to Speciesof Psorophora(Males) ......... 24 of other mosquitospecies. A SYNOPSISOF "' THE MOSQUITOES '; OFILLINOIS (Diptera,Culicidae) / Herberr H. Ross William R. Horsfall ............ ß...... •----•.•-• •.•. FIG. 1.--Adult of Aedesaegypti. (From photograph,lent by the U.S. Public Health Service, of model in the American Museum of Natural History.) TO ALL OF US WHO LIVE IN ILLINOIS, mos- of their life histories. All of them,however, have many quitoesare familiaras pests that attackpersons and live- characters and habits in common. The immature form stockout of doorsfrom springto fall. or larva (known as a wriggler) is aquatic,that is, it They may be of greater consequencethan simply livesin water. This form requiresseveral to manydays as biting pests. Somekinds are solelyresponsible for to becomea full-grownlarva. At this time, it transforms transmittingcertain parasites to man and domesticani- into the next life historystage, the pupal (as pupae, mals. Blood parasitessuch as thosethat causemalaria, mosquitoesare called tumblers), and this stage also is yellowfever, dengue, and filariasis must have mosquitoes aquatic. The pupal stage,which lastsonly a few days, to take them from sickto well persons. Severalof the is a transformationstage; within the pupathe tissuesof encephalitis-producingultramicroscopic viruses that at- the larva are transformed into those of the adult mos- tackthe brainand spinalcord are carriedsolely by mos- quito. When the transformationis complete,the pupa quitoesfrom wild animalsto man or from man to man. floats at the surface of the water, its shell cracks and Past control efforts againstmosquitoes have reduced breaksthe surfacefilm, and the wingedadult emerges. someof thesediseases to insignificance.Other diseases Adult mosquitoes(Fig. 1) are entirelyaerial and carriedby mosquitoesstill riseat timesto plagueus. neverenter the water. After a period of feedingand To date,mosquitoes of 55 differentspecies have been mating, the femaleslay eggseither on the surfaceof taken in Illinois. Seven additional species,known in the water or in soil that will be flooded at a later date. neighboringstates from situationssimilar to those in Eggslaid on the waterhatch in a few days;each small this state,may alsooccur in Illinois and are includedin larva emergesdirectly into the water from the end of this synopsis.These 62 species,along with severalhun- the eggthat sticksinto it. Eggslaid in soil hatchwhen dred more in other parts of the world, constitutethe thesoil is floodedand the eggsare covered by the right family Culicidae. This family and a hundredor more kind of water. additionalfamilies of two-wingedflies together comprise This synopsisprovides means for identifyingthe the orderDiptera. mosquitoeslikely to be found in Illinois. It contains The Illinois speciesof mosquitoesdiffer from each keysto eggs,larvae, and adults,because the sanitarian, other in the habitatsthey frequentand in manydetails ecologist,and collectorworking with mosquitoeswill find all stagesof the insectsand may not havethe time This paper is printed by authority of the State of Illinois, or meansto rear the insectsto other stages. It is an IRS Ch. 127, Par. 58.22. It is a contribution from the Section of raunistic Surveys and Insect Identification of the Illinois extensionof the originalreport, The MosquitoesoJ Illi- Natural History Survey. Dr. Ross is head of that section. Dr. YIorsfall is a Professor of Entomology, Department of Ento- nois (Ross1947) in that it includesmore speciesand mology, University of Illinois. The authors wish to express special thanks to James S. presentsa key to eggsof floodwatermosquitoes. Most Ayars, the Survey's Technical Editor, for the creative way in which he has contributed to the production of this Synopsis. of thekeys in thissynopsis have been enlarged from the YIis unstinting and understanding help in simplifying terminol- original report; someof the illustrationsare from the ogy, rephrasing couplets, and clarifying concepts has made this publication useful to a much wider circle. originalreport and some are new. For convenience,the keysto generaand specieshave gateproboscis many times as long as the head, (2) an- beenarranged according to the life historystages of the tennaewhich are much longer than the head and are insects.A personwishing to identifya femalemosquito composedof manysmall, well-separated segments, many will find all the keys for the identificationof females, segmentseach with a ring of hairs, and (3) wings with both to generaand to specieswithin the variousgenera, an arrangementof veins depictedin Fig. 6. A pupa groupedtogether in the samesection. Keys for the is characterizedby being active in water, by having a identificationof males,larvae, and eggsare groupedin curledposture, and by havinga pair of respiratorytubes similar fashion. At the head of each section there is on the dorsumof the thorax (Fig. 2). The pupaeare includeda diagramof the stageconcerned. The dia- gramsare labeledto show the diagnosticareas or parts mentionedin the keys. If only one speciesof a genus occursin Illinois, it is indicatedand treatedin the keys to genera. Eachof the other speciesis treatedin one of the keysto genera;these keys are arrangedalphabeti- callyby genera. Names of certaingenera and speciesmay appearin more than one placei n a key. This practiceallows the useof a large numberof charactersfor recognizingcer- tain distinctivegroups of specieswithin a genusor cer- tain distinctivevariations within a species. The cardinaldirections used for orientingparts of the mosquitobody or appendagesare as follows: apex---Theportion away from the point of attachment; concerningthe abdomenor its segments,the part F•G. 2.--Pupa of mosquito. The two respiratorytubes are more distant from the head. visible in the upper left part of drawing. (After King, Bradley, apical--On or pertainingto the apex. & McNeel 1939.) base--Theportion at the point of attachment;in rela- tion to the abdomenor its segments,the part nearer not diagnosedin this report. A larva of the Culicidae the head. canbe differentiatedfrom other aquatic,free-swimming basal--Onor pertainingto the base. insect larvae by the following combinationof charac- anterior--Forward, toward the head, or in front of. ters: (1) legsabsent; (2) head large and possessinga posterior--Backward,toward the rear, or backof. hard covering; (3) thorax large and wider than the dorsum--Theupper part or back. abdomen;(4) the respiratorysystem opening dorsally dorsal--Onor pertainingto the dorsum. on the next-to-lastsegment of the abdomen;(5) four dorsally--In the directionof the dorsum. blade-like"gills" extendingposteriorly from end of last lateral--Onor pertainingto thesides. abdominalsegment (Fig. 125, 126). In many species, laterally--In the directionof the sides. the larva hasa long or stout,usually hard and dark, air meson--Themidline down the lengthof the animal. tube (Fig. 125). Eggsof mosquitoesare blackor gray mesal--Onor pertainingto the meson. in color,sausage-like or spindle-likein shape,and each renter--The underpart or belly. not morethan 1 mm long. ventral--On or pertainingto the venter. Membersof