The Two-winged Flies 



35 



some have aquatic immature stages and some terrestrial; while the larvae 

 and pupa? of all the members of the remaining three live in plants or in the 

 ground, none being aquatic. 



Best known of the aquatic families, and indeed of the whole suborder, 

 is the mosquito family, the 

 Culicidae. While the different 

 kinds of mosquitoes are much 

 alike, so much so indeed that 

 most of us are quite content if 

 we can determine an insect to be 

 a mosquito without carrying the 

 identification farther, there are 

 known in the world at least 300 

 different mosquito species, rep- 

 resenting two dozen distinct 

 genera. In North America 

 nearly 60 species are already 

 known, representing 10 genera, 

 and new ones are being found 

 constantly. In the family Culi- 

 cidae are included two distinct 

 general types of mosquito, one 

 with mouth-parts forming a long, 

 slender, sucking proboscis, pro- 

 vided with sharp, needle-like 

 stylets for piercing (Fig. 411), the 

 other with the mouth-parts short 

 and better adapted for lapping 

 or sucking up freely exposed 

 liquids. The latter type of 

 mouth is possessed by but two 

 genera, all the others being 

 piercers and blood suckers (in 

 the female sex). Of these pierc- 

 ing genera three are of especial 

 importance and interest to us 

 because of their abundance and 



their definitely determined relation to the development, incubation, and dis- 

 semination of certain serious diseases of man. These three genera are Culex, 

 Stegomyia, and Anopheles. To Culex belong the great majority of familiar 

 mosquitoes which pursue and harass us with their songs and bites; to Stego- 

 myia (and Culex) belong the mosquitoes held responsible for the dissemination 



FIG. 413. The life-history of a mosquito, 

 Culex sp A small raft of eggs is shown on 

 the surface of the water, several larvae 

 ("wrigglers"), long and slender, and one 

 pupa ("tumbler"), large-headed, are shown 

 in the water, and an adult in the air above. 

 (From life; much enlarged.) 



