FOOD OF LARVA5 151 
bred C. nigritulus almost exclusively upon flagellate protozoa which seem to he 
a very favorite food of this species. In our experience the larvee of Aédes, which 
occur in early spring, when small crustacea often abound, do not feed upon these 
latter. In confinement the Aédes larve do not thrive if many crustacea are 
present in the water and probably these deprive the mosquito larve of their food. , 
In nature these Aédes larve are largely bottom feeders and they may be seen 
vigorously working over the dead leaves and vegetable debris with their mouth 
organs, apparently removing the fungoid growth which covers them. 
Certain larvae thrive best where animal refuse abounds in the water and this 
is particularly true of the species associated with man. The larve of Culex 
pipiens and Culex quinquefasciatus develop most rapidly in water charged with 
fecal matter or animal refuse. The same has been asserted for the yellow-fever 
mosquito by the Brazilian observers. We have found that the larve of this 
species thrive in comparatively pure water, in collections of rain-water, in jars 
or bottles of drinking water. Unavoidably such water, kept in or near the house, 
although clear, does contain a certain amount of animal matter and it is upon 
this the larve feed. 
The food of the larve of the pitcher-plant mosquito (Wyeomyta smithi) con- 
sists altogether of the remains of insects that have been trapped by the plant. 
The presence of such food, and its amount, are largely a matter of accident and 
upon it the growth of the larve depends. Sometimes no insects find their way 
into a water-filled leaf for a considerable time but the larve can endure starva- 
tion for a long period. Larve of this species which we have kept without food in 
the laboratory, lived nearly a whole year. Probably the larvee of all the species 
of Wyeomyia are scavengers feeding upon insects’ remains, although those in the 
bromeliads at least, have access to vegetable debris. The larve of Joblotia and 
LIimatus appear to feed wholly upon dead insects and their remains and their 
powerful mandibles are well fitted for this work. 
It has already been mentioned that the larve of certain genera are predaceous, 
in every case feeding upon other mosquito larve.. The genera known to have 
predaceous larve are Celodiazesis, Megarhinus, Psorophora, Lutzia, Lestico- 
campa and Sabethinus. Each of these larve has its own peculiar habitat and as 
a result it is limited in its food to the larve found there. The larve of Celo- 
diazesis barbert occur in water in hollow trees and there they prey upon the 
larve of Bancroftia signifer and Aédes triseriatus. These larve have another 
formidable enemy in the larva of Megarhinus septentrionalis which usually 
occurs singly or in small numbers in tree-holes. Some of the tropical species of 
Megarhinus also live in tree-holes—others are partial to bromeliads and to 
bamboos, while one occurs in cocoanut-husks and preys upon the larve of 
Joblotia digitatus. The larve of Psorophora occur almost wholly in rain- 
puddles where the predaceous species feed upon those of the subgenus Janthi- 
nosoma and of Aédes. They are extremely voracious and consequently their 
development is very rapid. Lutzia is a continuous breeder and consequently 
preys more largely upon Culex larve. The habits of the predaceous sabethine 
forms are very imperfectly known. The larvee of different species of Lestico- 
