MOSQUITOES AND FLEAS. 



15 



The length of time which ehipses for a generation, wliich we have 

 just mentioned, is ahnost indefinitely enlarged if the weather be cool. 

 As a matter of fact, a long spell of cool weather followed the issuing of 

 the adults just mentioned. Larvjc were watched for twenty days, dur- 

 ing which time they did not reach full growth. 



The extreme shortness of this June generation is significant. It 

 accounts for the fact that swarms of mosquitoes may develop ux>on 

 occasion in surface pools of rain water, which may dry up entirely in 



Ym. ^.—Cnlex pungens : Full-grown larva at left; pupa at right al)i 



greatly enlarged (original). 



the course of two weeks. 



', Jt8 anal segment l)elow— all 



or in a chance bucket of water left undis- 

 turbed for that length of time. Further, the shortness of this genera- 

 tion was, while not unexpected, not at all in accordance with any i)ub- 

 lished statements as to the length of life of any immature mosquito of 

 any species. But these i)ublished statements, as previously shown, 

 were nearly all based upon observations made in a colder climate and 

 in the month of May. 



On August 1 Mr. F. G. Pratt, an assistant in the division of euto- 



