398 Inland Water Culture 



Mayflies, like Callibastis and the little Casnis, that 

 have a number of broods each season with overlap of 

 generations, are suited for use in forage propagation 

 because at all times of the year nymphs of good size are 

 present in the water. On the other hand, such forms 

 as Blasturus cupidus, which flies in May, and Siphlurus 

 alternatus which flies in June, are absent from the water 

 at the close of their breeding season or are represented 

 there only by eggs and very minute nymphs. 



Best known of the mayflies that fishes eat are the 

 nymphs of the big burrowing Hexagenias from lake 

 and river beds. Food examinations have abundantly 

 shown their importance. However, they develop 

 slowly, requiring at least two years to reach maturity. 



The Hexagenia nymphs are natural associates of 

 bloodworms on the lake bottom. They, and the blood- 

 worms with them, and the entomostraca swimming 

 above them are the mainstay and dependence of the 

 lake's fish population. 



Other herbivorous insects of promise as forage organ- 

 isms are caddis- worms and aquatic caterpillars. Other 

 invertebrates are a number of pond snails. But the 

 animals above discussed we regard as most important. 



Forage fishes — The largest single item in the bill-of- 

 fare of fishes generally is other smaller fishes. Herbi- 



FiG. 238. The golden shiner. 



{Photo by George C. Embody) 



