914 



FRESH-WATER BIOLOGY 



There remain three large families of the diptera of very great im- 

 portance. Two of these, the Culicidae and the Tabanidae, are impor- 

 tant because of the damage they do, and the other, the Chironomidae, 

 because of the food it furnishes to fishes. The mosquitoes (Culi- 

 cidae), since the discovery of their importance to man as agents 

 for the dissemination of the germs of malarial and other fevers, 

 have suddenly become well known. A number of good books are 

 now available containing descriptions, figures, and detailed accounts 

 of the habits and Hfe histories of the economic species. Some of 

 the most interesting members of the family are not included in these 

 books among the pests, since the adults do not bite. Corethra^ 

 whose phantom larvae are a part of the plankton, is one of these, 

 and Pelorempis, the large culicid inhabitant of cold springs is 

 another. 



The biting adults of the large horse-flies (Tabanidae) are like- 

 wise serious pests of the domesticated animals. Their naked 



Fig. 1383. The speckled midge, Tanypus carneus, male. 



translucent larvae, tapering to either end and ringed with fleshy 

 tubercles, are carnivorous, and are found in the trash of the 

 bottom in all shoal fresh waters. But two genera, Tahanus and 

 Chrysops, are of much importance in our fauna. 



The midges (Chironomidae, Fig. 1383) constitute undoubtedly 



