160 



GNATS OR MOSQUITOES — CHAPTER VII 



in the communications one reads from various parts are 

 simply due to the fact that the tastes of different species of 

 fish as to their food diflfer Uke those of other orders of 

 animals. That fish and Mosquitoes are constantly found 

 in company in the Madras rice swamps simply shows that 

 the species found there do not happen to be larvivorous, 

 and in no way discredits the accuracy of other observers, 

 who find that gnat larvae are unable to exist in water that 

 contains fish of probably entirely different sorts. Per- 

 ijonally I have never found fish in the same pool with larvae 



Fig. 32. —Caudal extremity of Anopheles Rosii infested by a parasitic 



stalked infusorian. 



though, like Mr. Aitken, I find that they and tadpoles, and 

 I may add frogs, seem to be able to live together as excel- 

 lent friends. Mr. Aitken says : " From my experience I 

 should say that, of all larvicides, the most effectual, in the 

 case of Anopheles, is little fishes. I have never found larviP 

 and fishes in the same pool. Once I put a large number 

 of larvae into two glass vessels and introduced a few gold 

 fish into each. Next morning there was not one larva 

 in either. They have many insect enemies; too, especially 



