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, nonfeeding stage the pupa or nymph. 

 There the head and thorax are combined in an oval body, from the back of which 

 projects the siphon tubes; and tucked in ventrally is a small tail- like appendage. 



The fully developed insect emerges from the pupa. 



The Culicidae belong to the suborder Nematocera. These have long articulated 

 antennae and include four families: Culicidae Chironomidae, Simulidae, and Psycho- 

 didae. 



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

 frequently mistaken for mosquitoes 'none of which have scales on their 

 wings are the following: 



1. Chironomidae or Midges. The blood-sucking species of Chironomidae, which 

 are found in most parts of the world, 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 trouble- 

 some. The antennas have thirteen joints and the wings are shorter than the 

 abdomen and have only longitudinal veins. One of the. midges, the "jejen" 

 of Cuba, is a great scourge, its small size enabling it to enter eyes and nostrils. 

 The larva of Chironomus is a red worm-like creature; the pupa has a tufted 

 head. 



2. Simulidae or Buffalo Gnats. These are small blood-thirsty insects only about 

 1/8 of an inch in length. The thorax is humped, the legs are short and the 



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