﻿IX, B, 5 Walker and Barber: Malaria in the Philippines 



421 



In the text and tables that follow, the details of these experi- 

 ments are discussed at length under appropriate headings. 



THE DEVELOPMENT OF ANOPHELINE LARV>E IN CAPTIVITY 



The rearing of adult anopheline mosquitoes from mature or 

 nearly mature larva and from pupae in the laboratory presents 

 no difficulties, as the majority of them live to emerge as imagoes 

 within a few days; on the other hand, large numbers of the 

 younger larva fail to develop and die in the breeding jars. This 

 is possibly due in part to the stagnant condition of the water in 

 the breeding jars and in part to the lack of proper food. The 

 water in our breeding jars was aerated daily, as recommended by 

 Darling (1910), and no difficulty was experienced with foulness 

 of the water due to the development of anaerobic bacteria. In 

 collecting larvae, more or less of their natural food was undoubt- 

 edly included, and in many cases algae, pond weeds, or debris, 

 in which the larvas were found, were added to the breeding jars. 

 Duck weed, which in some cases was found associated with the 

 larvae in nature, when added to the breeding jars quickly over- 

 grows the surface of the water and prevents the larvae from 

 coming to the surface for air. It is probable that the develop- 

 ment of a larger proportion of the younger larvae would be 

 secured if they could be bred in the tanks furnished with run- 

 ning water and supplied with an abundance of natural food. In 

 practice it was found best to collect, so far as possible, the larger 

 larvae and pupae. 



PROPORTION OP FEMALES TO MALES IN ANOPHELINES BRED FROM LARV^ IN 



CAPTIVITY 



This is best shown in a table constructed from the data of those 

 experiments in which the males and females were separated and 

 counted. The counts were made of the mosquitoes after feeding 

 on the malaria patient in the cages in which they were collected 

 from the breeding jars, and include the dead as well as living 

 mosquitoes. They are, therefore, approximately accurate. 



Table III. — Proportion of females to males in anophelines bred from larvas. 



Species. 



Lots of 



mogqui- 



toes. 



Males. 



Anopheles febrifer 



Anopheles rossii 



Anopheles barbirostris 



Anopheles sinensis 



Anopheles vnaculatus-. 



Total 



35 



37 



23 



4 



1 



100 



697 



787 



206 



96 



3 



1,789 



Females. 



812 



1,073 



289 



143 



2 



2.319 



Females. 



Per cent. 

 63.8 

 57.6 

 58.3 

 59.8 

 40.0 



56.4 



