39 



The larva^ first studied — those which hatched from the eggs on 

 April 30 — grew very slowh' for a number of da^^s. This was partly 

 owing to cool weather in the early part of May, and parth^, I believe, 

 to the absence of proper food. The}^ were reared in glass jar^ of water, 

 with sand at the bottom and a willow twig rooting in the sand. As 

 above noted, they 

 swallowed every 

 small particle floating 

 on the surface of the 

 water, and the dark 

 coloration shown in 

 fig. 14 was largeh' 

 due to the fact thai 

 most of these food 

 particles were dark 

 colored. About the 

 10th of May, the 

 larvse having passed 

 through two molts, 

 a small quantity of 

 the green algas grow- 

 ing on the lily ponds 

 on the Department 

 grounds was placed 

 in the jar. ^ The larvae 

 commence to thrive 

 much better, grew 

 rapidly, and the gen- 

 eral color of the body 

 changed to green. 

 The description of 

 the habits given 

 above held well until 

 after the last molt 

 preceding the change 

 to pupte. In this final 

 larval stage, as shown 

 in fig. 15, the diameter fig 

 of the thorax ))ecame 

 much greater in com- 

 parison with the rest of the body. The larva was less marked, more 

 inconspicuous, and altered its feeding habits to some extent. After 



'These algse were studied by Mr. A. F. Woods, of the Division of Vegetable Phys- 

 iology and Pathology, who informed me that the larger part belong to a species of 

 the genus G^dogonium, but that there was also quite a large amount of a species of 

 Cladophora, with some Spirogyra. There was also some of the blue green Oscilaria, 



15. — Anopheles qaadrimaculatus: Full grown larva in feeding 

 position, seen from above (head reversed, in feeding position); 

 dorsal side of head above at right — greatly enlarged (original). 



