THE MALARIAL MOSQUITOES 



103 



The larv.^ first studied — tliose which hatched from the 

 eggs on April 30th — grew very slowly for a number of 

 days. This was partly owing to cool weather in the early 

 part of May, and partly, I believe, to the absence of 

 proper food. They were reared in glass jars of water, with 

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





Fro. 21. Full-grown Larva of Anopheles maculipennis slinwing head 



upside down, with top of head above, at left ; greatly enlarged. (Au- 

 thor's illustration.) 



As above noted, they swallowed every small particle float- 

 ing on the surface of the water, and the dark coloration 

 shown in Fig. 18 was largely due to the fact that most of 

 these food particles were dark colored. About the 10th of 

 May, the larv» having passed through two molts, a small 

 quantity of the green algfie growing on the lily ponds on 

 the Department grounds was placed in the jar. The 



