THE FARM STREAM 



39 



be seen without a 

 lens and too nvim- 

 erous even to be 

 mentioned here. 

 The water is like 

 another world of 

 life, containing a 

 few forms that are 



directly useful to p^^ gl. Adult aquatic insects: a, the back swimmer 

 11Q anH manv mnrf» (Notonecta); &, the water boatman (Corixa); c, a diving 

 ua aiiu i.Li<x.Liy iiiui c j^^^j^ (Dytiscus) ; and d. a giant water-bug (Benacus). 



that furnish for- 

 age for these; containing a few that are noxious when 

 adults, such as black-flies, horse-flies and mosquitoes, and a 

 host of other forms, all of interest to the naturalist, but not 

 known to be of practical importance. They are all a part 

 of the native population of the stream and each has a share in 

 carrying on its natural social functions. 



In the water as on land, green plants represent the great 

 producing class while animals and parasitic plants are the con- 

 sumers. And among 

 the animals there 

 are herbivores and 

 carnivores, parasites 

 and scavengers. 



One who but casu- 

 a 1 1 y examines the 

 animal life of the 

 stream is apt to see 

 chiefly carnivorous 

 forms : for these are 

 most in evidence: 

 for here, as else- 

 herbivores. 



Fig. 22. 



a diving beetle, 



, _ ■' ■ : b, 



dobson larva, 



Lintner); and c, an orl-fly larva, Siolis (after Maude Vjgjjj^g OOOrlv 



Aquatic insect larvae: 

 Coftoiomus (.aiter Helen Williamson Matthews): 6, a _.-u„^„ 

 ' ' ■ r hellgrammite, CoryrfoKs cornato (after wiicic, 



H. Anthony). 



