CHAPTER XXI. 

 THE MOSQUITOES. 



MOSQUITOES (Culicidae) are of the greatest importance medically, 

 not only from their influence upon health in general by reason of inter- 

 ference with sleep and possibly from direct transmission of disease, but, 

 more specifically, they are the only means by which it at present appears 

 possible to bring about infection with such diseases as yellow fever, 

 malaria, filariasis and possibly dengue. In addition, many diseases 

 of animals are transmitted by mosquitoes. 



The Culicidae differ from all other Diptera in having scales on their 

 wings and generally on head, thorax or abdomen. 



To identify a mosquito, examine a wing and note the scales; also 

 note the presence of two distinct fork cells and, in addition, that the 

 costal vein passes completely around the border of the wing, making a 

 sort of fringe with its scales. Mosquitoes undergo a complete 

 metamorphosis, there developing from the egg a voracious, rapidly- 

 growing larva; next, a nongrowing, nonf ceding stage the pupa or 

 nymph. There the head and thorax are combined in an oval body, 

 from the back of which projects the syphon tubes; and, tucked in 

 ventrally is a small tail-like appendage. 



The fully developed insect emerges from the pupa. 



The principal mosquito -like, blood-sucking Diptera which are 

 frequently mistaken for mosquitoes none of which have scales on their 

 wings are the following: 



i. Chironomidae or Midges. The blood-sucking species of 

 Chironomidae, which are found in most parts of the w r orld, 

 belong chiefly to the genus "Ceratopogon." These 

 midges are of very small size, about 1/12 of an inch long, 

 are able to get through netting and, usually being in 

 swarms, they are exceedingly troublesome. One of the 



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