﻿422 The Philippine Journal of Science isi* 



From this table it is apparent that the females outnumbered 

 the males in every species but Anopheles maculatus. However, 

 in this species the number of mosquitoes is too few to draw any 

 conclusions. Authors have sometimes complained of a prepon- 

 derance of males among mosquitoes bred from larvae in the 

 laboratory, and it has been supposed that this preponderance was 

 due to lack of sufficient food in the breeding jars. As Table 

 III shows, we have not experienced this difficulty; in our lots 

 of laboratory-bred mosquitoes of 5 species, the males and fe- 

 males have varied more or less in the different lots as is to be 

 expected, but on the whole there has been a slight preponderance 

 of females. 



THE LONGEVITY OF ANOPHELINES IN CAPTIVITY 



We have succeeded in keeping a fair proportion of our mos- 

 quitoes alive from five to eighteen days, a time sufficient for the 

 development of the malarial parasite to the oocyst or sporozoite 

 stages. The different cages of mosquitoes showed considerable 

 variation in this respect, even in the case of the same species, 

 reared and kept under apparently the same conditions. At the 

 beginning of our investigation, during the cool season, but little 

 difficulty was experienced in maintaining a fair proportion of 

 mosquitoes alive to the time of dissection. As the hot season 

 approached, the mortality occurring among our experimental 

 mosquitoes increased. The use of wet cotton and filter paper as 

 a bottom for our cages was therefore discarded, and after ex- 

 perimenting with moist earth and other materials moist sand 

 was finally substituted, which proved successful in maintaining 

 the life of the mosquitoes in captivity. Undoubtedly, if our 

 mosquitoes had received unlimited personal attention, a larger 

 proportion would have survived, but owing to the pressure of 

 work the care of them had to be intrusted to the laboratory boy, 

 who was also overworked and necessarily neglected them at 

 times. Experiments 95 to 227a, in which both the number of 

 mosquitoes that fed on blood and the number that lived to be 

 dissected were determined, supply the following data bearing on 

 this question. In all cases the mosquitoes had emerged from 

 twenty-four to forty-eight hours before biting, and were con- 

 sequently from 1 to 2 days old when the experiment began. 



