•908 PEOCEEDIl'TGS OF THE THIHD ENTOMOLOGICAL MEETING 



where such food is most plentifiil. Indeed, the names of the groups 

 themselves are given according to the habitat rather than the food eaten 

 by the difEerent kinds of fish. As is evident, the fish very seldom could 

 get hold of the adult insects owing to the latter flying above the surface 

 of- water, but cases are known where fairly large fishes remain swimming 

 near the surface in the evenings and jump out of water to pounce on 

 the insects flying near the surface. An import^ant use of this habit is 

 made by the anglers who use artificial and fresh flies as baits for these 

 fishes and the fish rising to these attractive but deceptive baits get hooked 

 and supply the anglers with a nice form of sport. Some of the beetles, 

 bugs and other insects that live permanently in the water are either 

 too active for the fish or have a very hard chitin and are, therefore, 

 usually avoided by fish. Some interesting observations on this Jatter 

 head have been recorded. The fish were found to learn gradually by 

 experience the futility of securing such undesirable types of food and later 

 avoided them altogether. The most important part of the food of fish 

 from amongst the insects are the larval stages of some orders of insects. 

 These larvae abound in most waters, subsisting on the vegetation, the 

 protozoan animals and the small Crustacea, and are in turn eaten in large 

 quantities by the fish. The chitinous covering of these larvae is very 

 thin and poorly developed, and the comparatively large quantity of fleshy 

 substance of their body is very important as food to the fishes when 

 compared to the quantities of small Crustacea that must be eaten to get 

 an equal quantity of nourishment. Whereas for obtaining enough plank- 

 ton fish have to take in large quantities of water and to strain the plankton 

 from it ; they have only to dart a number of times at the comparatively 

 large insect-larvae and very soon to obtain equal quantities of food. 

 Our information in India regarding most of these points is most scanty. 

 In Europe and America where systematic experiments have been carried 

 on, larvae of the may-flies {Ephemeridw), dragon-flies {Odonata), some 

 of the Neuroptera, and amongst the two winged-flies {Diptera) those of 

 the families of crane-flies (Tipulidce), mosquitos {C^dicidw) phantom- 

 larvae (Corethra), harlequin-flies {Chironomidce), Dixidce and others, 

 have been shown to form a large quantity of the food of some fishes. 

 In fact, a celebrated Carp-culturist suggested the desirability of increasing 

 the mosquito larvae in the carp-ponds by specially devised means for 

 increasing this soiurce of the food supply of the fish ; he was naturally 

 ignorant of the harm that would accrue if larvae escaped from the fish 

 and developed into the adult mosquitos. AUthesame the fishes are im- 

 portant agents in keeping down the numbers of these objectionable insects. 

 A very important economic use has been claimed from the sanitary 

 point of view for utilising the fish as destroyers of mosquito larvae. Un- 



