HABITS OF ADULTS 433 



resting pupal stage. Mosquitoes of temperate climates usually 

 take from five days to two weeks to complete the larval existence, 

 depending almost entirely on temperature. In the mosquitoes 

 adapted to take advantage of transitory rain-pools the larvae may 

 transform into pupae within two days and the pupal stage is a 

 mere matter of hours. On the other hand, some mosquitoes 

 habitually pass the winter as larvae. 



The general form of the pupa can be seen in Fig. 197. Alcock 

 has aptly described this stage of a mosquito as resembling a 

 tiny lobster deprived of ap- 

 pendages and carrying its 

 tail bent. The pair of ear- 

 like breathing tubes on the 

 cephalothorax (head and 



Gnt.C- -*-^(pr_-* 



thorax fused) take the place 



of the trumpet-like tube of eye -- ; 



the larva and are used in 



the same manner. Unlike 



the larva the pupa is lighter 



than water, and requires 



muscular effort to sink in- . FlG - 197 - Pu P a of house mosquito Culex 



pipiens: ant. c., antenna! case; br. t., breath- 

 Stead Of to rise. i ng tubes; leg. c., leg cases; pad., paddles; 



As remarked before, the win s c., wing case, x 10. (After Howard, 



Dvar and Knab.) 



transformation into the 



adult during the pupal stage may be a matter of a few hours in 

 the case of the dry-climate mosquitoes, but in most species it re- 

 quires from two days to a week, depending on the temperature. 

 The adult mosquito emerges head first through a longitudinal 

 slit along the back of the thorax. After its exit it rests for a 

 moment on the old pupa skin, stretches and dries its wings, and 

 then takes flight. 



Habits of Adults. Adult mosquitoes vary to a remarkable 

 degree as regards habitats, feeding habits, mode of hibernation, 

 choice of breeding grounds, and other habits. The knowledge, 

 only recently gained, that each species of mosquito has habits 

 and habitats more or less peculiar to itself, is of great economic 

 importance, since it does away with useless expenditure in com- 

 bating harmless or relatively harmless species, and aids in the 

 fight against particularly noxious ones. The fact, for instance, 

 that one of the commonest summer mosquitoes of northeastern 



