CHAPTER II 



SOME DISEASE-BEARING AMERICAN MOSQUITOES 



THE MOSQUITO IN GENERAL 



While mosquitoes have a world-wide distribution, they differ 

 very materially in their habitat, their appearance, their ability 

 to transmit disease, the character of their breeding-places and 

 the mode of continuing their existence from one generation to 

 another. 



From the point of view of habitat, mosquitoes may conven- 

 iently be divided into three general classes: The domestic mos- 

 quito, which breeds largely about homes, as Aedes calopus, the 

 yellow fever mosquito; the fresh-water sylvan mosquito, which 

 breeds in pools, swamps, streams, ponds, etc., as the Anopheles, 

 the malaria-carrying mosquito; and the salt-marsh mosquito, 

 which breeds almost entirely in brackish marshes along the sea, as 

 Culex sollicitans. It is the domestic and fresh-water sylvan 

 mosquitoes which constitute the menace to health. 



Of its own volition, the mosquito seldom travels far. Experi- 

 ments indicate that, as a rule, the inland mosquito does not fly 

 more than half a mile or so from its breeding-place and that the 

 average flight is much less than this distance. The}'' may, how- 

 ever, be wafted considerable distances by the wind, and this fact 

 should be borne in mind in planning anti-mosquito work; the 

 control area should extend, say, a mile or more in the direction of 

 the prevailing wind, while the other side may be reduced in width 

 to half a mile. 



LIFE HISTORY OF THE MOSQUITO 



Although the mosquito is a winged animal, no fewer than 

 three of the four stages of its life are aquatic, and these are the 

 first. The egg is laid in a quiet pool or other suitable breeding- 

 place; if the weather is warm, in a couple of days the eggs hatch 

 out into larvae (wiggletails or wrigglers) ; in 4 or 5 days more the 

 larvae turn into pupae; this stage lasts 2 or 3 days, when the 

 adult mosquito emerges from the pupal shell. Therefore, if 



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