396 



I)i land Water Culture 



Chironomus lays several hundred eggs, and in the 

 warm season a generation may completely develop in 

 five or six weeks; so the very considerable increase of 

 one brood may be rapidly repeated in geometric ratio. 



The limitations to its use as a forage organism in fish 

 ponds lie in its complicated life history. It quits the 

 water at the end of the pupal stage. It flies away, 

 mates in the air, and returns to the water to lay its eggs. 

 During its aerial life it is not easily managed. 



Mayfly nymphs constitute one of the most important 

 groups of aquatic herbivores. We single out Callibsetis 

 for illustration of another staple fish food. It is an 

 active nymph that swims from place to place by means 



. J^ 



^p — ? / ' 



Fig. 237. The nymph of Callibaetis: Drawing by Anna H. Morgan. 

 (From Annals Ent. Soc. America) 



