Air tube long and slender; pecten consisting of only 

 a few sclerous teeth on basal por.ion or tube (Fig. 



171A) 3 



3. Head hair 5 usually with 7 or more branches; ventral 

 brush usually with 18 or fewer tufts; head hair 7 

 usually with 9 or more branches minnesotae 



Head hair 5 usually with 5 or fewer branches ( Fig. 

 171B); ventral brush usually with 20 or more tufts 

 (Fig. niA); head hair 7 usually with 8 or fewer 

 branches (Fig. 171B) morsitans 



Key to Species of ORTHOPODOMYIA (Larvae) 



Larvae of these two species live only in tree holes. 

 Head medium to dark brown, body pink; segments 6, 7, 



ANAL 

 SEGMENT 



and 8 usually with dorsal sclerotized plates, the plate 

 of segment 8 frequently extending ventrad to the ven- 

 tral margin of the comb (Fig. 127/4); these sclerotized 



plates may be entirely absent signifera 



Head pale yellow to white, body white to straw color; 

 segments 6, 7, and S without sclerotized plates. . .alba 



Key fo Species of PSOROPHORA (Larvae) 



Larvae of all Illinois species of Punoplidu live in flood- 

 waters, almost invariably in pools which fill after a rain. 



lIG. 176. — Psorophora horrida. larval parts. (After Roth 19-15.; FiG. 1"7. — I'sorophora loiinipalpis. larval j-arts. (After Roth 19)5.) 



43 



