42 AGRICULTURAL EXPERIMENT STATION. 



often of considerable extent. When the air is full of moisture, 

 evaporation is slow and an occasional shower, even if light, 

 serves to keep up the supply. The heat favors the development 

 of the micro-organisms in the water, the wrigglers that will be 

 found in the pools within forty-eight hours after their formation 

 have an abundance of food, and in six to eight days from the 

 egg, adults appear. This applies to all kinds of mosquitoes, 

 whether inland or on the salt marsh, and a spell of such weather 

 may produce a brood of the marsh species where no tide has 

 covered the meadows for weeks. Clear, drying weather always 

 checks development even if there be no actual drought. So there 

 might easily be a season with plenty of rain, yet not well adapted 

 for mosquito breeding. On the other hand, no matter how dry 

 the weather, a high tide on the salt marsh may start the develop- 

 ment of a brood ; though in that case many of the shallow areas 

 would dry out before the larvse coud reach maturity. At some 

 points along shore "mosquito weather" is caused by specific 

 winds and the occurrence of the insects on these winds is due 

 simply to the favoring conditions for flights from the salt marsh. 

 Few insects are sO' dependent upon weather conditions as the 

 mosquito and yet fewer can take advantage of favorable con- 

 ditions so readily. 



CHAPTER IV. 

 HOW MOSQUITOES DEVELOP. 



THE LIFE OE A MOSQUITO. 



How long does a mosquito live? It is a simple question, not 

 easily answered, because the answer cannot be the same for all 

 the species. We know in general that the life of the male is 

 short, limited to a few days or until he has fulfilled his function 

 in life by impregnating the female. 



As to the females we know that some species hibernate, i. e., 

 live through the winter as adults, and we know that some of 

 them begin to seek quarters during the latter half of September. 

 We know also that there is no general exodus from hibernating 

 places until May and for such species there is a life of at least 

 seven and probably more nearly eight months. We have rather 

 assumed that in summer the length of life was determined, some- 



