26. Air tube 5 times as long as its width at middle of 



pecten, tapering markedly, so that the width of the 

 apex is about half the width of the base ( Fig. 

 146/4); its apical spine long and dark. Occurs dur- 

 ing spring in marshes fuchi 



Air tube at most 4 times as long as its width at middle 

 of pecten, tapering less than air tube in Fig. 146/J, so 

 that the width of the apex is about three-quarters 

 the width of the base (Fig. 144/4); its apical spine 

 short and inconspicuous 27 



27. Anal segment having 6 or more ventral tufts anterior 



to barred area, the tufts extending to the base of the 

 sclerous saddle. Occurs during spring in grassy 



temporary pools flavescens 



Anal segment having at most 5 tufts anterior to barred 

 area, the tufts extending only one-half to two-thirds 

 the distance to the base of the sclerous saddle, as 

 in Fig. 141/1 and 150/4 28 



28. Anal gills budlike, much shorter than the sclerous 



saddle, as in Fig. 135/4. Occurs in summer in pools 



containing industrial wastes dorsalis 



Anal gills as long as the sclerous saddle, not budlike 

 ( Fig. 144/4 ) 29 



29. Ventral tuft of air tube only about half as long as 



tuft posterior to lateral comb; sclerous saddle of 

 anal segment only slightly longer than deep, extend- 

 ing more than three-quarters distance down sides 

 of segment (Fig. 144/4 ). Occurs during spring and 



early summer in woodland floodplain pools 



sticticus 



Ventral tuft of air tube about as long as tuft posterior 

 to lateral comb; sclerous saddle of anal segment 

 much longer than deep, extending only one-half to 

 two-thirds distance down sides of segment (Fig 

 141/4) 30 



30. Lateral comb containing more than 40 scales. Occurs 



in spring in sphagnum pools communis 



Lateral comb containing 40 scales or less 31 



31. Head hair 6 usually double or single, occasionally 



triple; ventral tuft of air tube usually with 3 or 4 

 hairs (Fig. 141/4). Occurs during spring in wood- 

 land pools in the northern half of Illinois 



stimulans 



Head hair 6 usually double or triple (Fig. 150B), 

 occasionally 4-branched; ventral tuft of air tube 

 usually with 5 to 8 hairs (Fig. 150/4). Occurs 

 during spring in woodland pools in the southern 

 fourth of Illinois grossbecki 



Key to Species of ANOPHELES (Larvae) 



The larvae of the Illinois species of Anopheles live 

 among emergent vegetation and flotage in permanent or 

 semipermanent pools, the edges of lakes, and marshes, ex- 

 cept for those of harheri. which live in tree holes. 

 1. Head hairs 5, 6, and 7 short and simple (Fig. 156); 

 lateral body hairs with only short feathering. . . . 



barberi 



Head hairs 5, 6, and 7 long and plumose (Fig. 158); 



lateral hairs of thorax and first 3 abdominal seg- 

 ments with long feathering ( Fig. 162 ) 2 



Fourth and fifth abdominal tergites with hairs and 2 

 plumose (Fig. 162 ) crucians 



Fourth and fifth abdominal tergites either with hair 

 inconspicuous or with hair 2 only single or 

 double (Fig. 161) 3 



Fig. 161 (left). — Anopheles quaJrimaciilati/s. larva, portion of 

 dorsum. (After Ross & Roberts 1943.) 



Fig. 162 (right). — Anopheles crucians, larva, portion of dor- 

 sum. (After Ross & Roberts 1943.) 



3. Head hair 3 densely plumose, fan-shaped from base, 



with only an inconspicuous basal stalk (Fig. 160); 

 head hair 2 sometimes feathered at tip; prothoracic 



hair 1 sometimes branched walkeri 



Head hair 3 less densely plumose than that in Fig. 

 160, the fan-shaped portion having a long basal 

 stalk ( Fig. 1 59 ) ; head hair 2 never feathered at 

 tip; prothoracic hair 1 rarely branched 4 



4. Hair 1 of the second and fallowing abdominal segments 



having each branch flattened, the whole hair ap- 

 pearing like a short, spread fan (Fig. I6l ) 



quadrimaculatus 



Hair 1 of second abdominal segment with each branch 

 nearly hairlike, as in Fig. 162; fanlike hairs begin- 

 ning on third abdominal segment 5 



5. Bases of the 2 head hairs 2 wide apart ( Fig. 1 'i9 I . . . . 



quadrimaculatus 



Bases of the 2 head hairs 2 close ( Fig. 160) 6 



6. Head hair 2 alway.. ':imple (Fig. 1^8) . . punctipennis 

 At least 1 of the 2 heavl hairs 2 usually with a con- 

 spicuous branch ( I'ig. I 57) earlei 



37 



