39 
The larve first studied—those which hatched from the eggs on 
April 30—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. As 
above noted, they 
swallowed every 
small particle floating 
on the surface of the 
water, and the dark 
coloration shown in 
fig. 14 was largely 
due to the fact that . 
most of these food 
particles were dark 
colored. About the 
10th of May, the 
larve having passed 
through two molts, 
a small quantity of 
the green alge grow- 
ing on the lily ponds 
on the Department 
grounds was placed 
inthejar.* Thelarvee 
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 
topupe. In this final \ 
larval stage, as shown 
in fig. 15, the diameter Fic. 15.—Anopheles quadrimaculatus: Full grown larva in feeding 
of the thorax became position, seen from above (head reversed, in feeding position); 
x dorsal side of head above at right—greatly enlarged (original). 
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 
1These alge 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 (Gidogonium, 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, 
