46 MALARIA 



night between nine o'clock and midnight. This stage 

 is comparatively short, seldom lasting over thirty-six 

 hours. At the end of this time the pupal skin bursts 

 longitudinally along the dorsal side, the pupa in the 

 meantime having straightened out. In a few minutes 

 the adult has pulled itself out of the old skin, and quietly 

 balancing itself remains on top of its cast skin until 

 its wings are sufficiently dry to permit it to fly off to 

 a near-by resting-place. 



It can thus be seen that the process of emerging 

 requires a very quiet body of water ; otherwise the 

 mosquito would be submerged and perish. 



Duration of Adult Life. — As a rule, the newly 

 emerged females will suck blood after about twenty- 

 four hours. Numerous experiments tried on the male 

 mosquito, as well as extensive field observations, seem 

 to give conclusive evidence that these individuals 

 do not possess the blood-sucking habit and live ex- 

 clusively on the juices of plants and "plain" water. 

 However well one may care for the males, they usually 

 die within two or three days ; exceptional individuals 

 may live seven or eight days, and it is quite probable 

 that very little nourishment is taken, as a rule, during 

 this time. 



In captivity the mosquito mortality is very high 

 and it is not a satisfactory plan to estimate the average 

 length of life on the basis of laboratory observations. 

 Basing an estimate on the relative abundance of Anoph- 

 eline mosquitoes in a given district after careful con- 



