FOOD OF LARViE 151 



bred C. nigritulus almost exclusively upon flagellate protozoa which seem to be 

 a ver}' favorite food of this species. In our experience the larvae of Aedes, which 

 occur in early spring, when small Crustacea often abound, do not feed upon these 

 latter. In confinement the Aedes larvag do not thrive if many Crustacea are 

 present in the water and probably these deprive the mosquito Islvy^ of their food. 

 In nature these Aedes larvae 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 larvse thrive best where animal refuse abounds in the water and this 

 is particularly true of the species associated with man. The larvae of Culex 

 pipiens and Culex quinquejasciatus develop most rapidly in water charged with 

 faecal matter or animal refuse. The same has been asserted for the yellow-fever 

 mosquito by the Brazilian observers. We have found that the larvae of tliis 

 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 larvge feed. 



The food of the larvae of the pitcher-plant mosquito (Wyeomyia smitJiii) 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 larvie depends. Sometimes no insects find their way 

 into a water-filled leaf for a considerable time but the larvae can endure starva- 

 tion for a long period. Larvae of this species which we have kept without food in 

 the laboratory, lived nearly a whole year. Probably the larvae 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 larvae of Johlotm and 

 Limatus 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 larvae of certain genera are predaceous, 

 in every case feeding upon other mosquito larvae. The genera known to have 

 predaceous larva? are Ccelodiazesis, Megarhinus, Psoropliora, Lutzia, Lestico- 

 campa and Sabethinus. Each of these larvte has its ov/n peculiar habitat and as 

 a result it is limited in its food to the larvae found there. The larvffi of Ccelo- 

 diazesis barberi occur in water in hollow trees and there they prey upon the 

 larvae of Bana'oftia signifer and Aedes triseriatus. These larva? 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 larvae of 

 Joblotia digitatm. The larvae of Psorophora occur almost wholly in rain- 

 puddles where the predaceous species feed upon those of the subgenus Janthi- 

 nosoma and of Aedes. They are extremely voracious and consequently their 

 development is very rapid. Lutzia is a continuous breeder and consequently 

 preys more largely upon Culex larvae. The habits of the predaceous sabethine 

 forms are very imperfectly known. The larvas of different species of Lcstico- 



