FLIES, MOSQUITOES, AND MIDGES 



223 



forked abdomen. They breathe through the respiratory tube pro- 

 jecting upward from the abdomen, which is thrust through the 

 surface of the water as the wriggler rests at the surface. The 

 wrigglers feed on bits of organic matter and microorganisms. 

 The pupa has the head and thorax very remarkably enlarged, and 

 there are two breathing tubes which project from the back of the 



FIG. 352. Wing of a mosquito (Mansonia titillans Walk.) enlarged, showing 

 scales on veins, and a portion of same further enlarged 



(After Felt) 



thorax. The pupa stage lasts from one to three days, the whole life 

 from egg to adult requiring from eight days to two or three weeks. 

 Not only are mosquitoes exceedingly annoying, rendering some 

 sections almost uninhabitable, but it has been shown that malarial 

 fever is transmitted only by mosquitoes of the genus Anopheles, 

 and that the dreaded yellow fever is similarly carried only by species 

 of the genus Stegomyia, which has resulted in an entire change in 

 the methods of controlling these diseases. Very much can be 



