AQUATIC INSECTS 



Larvae. — Midge larvae occur in vast numbers in all fresh 

 waters. They are slender and wormlike, with fleshy prolegs 

 at each end of the body, and they arch their backs like measur- 

 ing worms (Fig. 228). Many of them cover themselves with 

 soft dirt tubes (Fig. 19). Networks of these tubes cover the 

 litter of dead leaves in the pools, and the sides of a collecting 

 dish where the "catch" has stood for two or three hours. 

 They are fragile and never portable like those of the caddis 

 worms but new cases are made whenever the larvas are forced 

 out of the old ones. 



Midge larvae feed entirely upon algae and decayed vegeta- 

 tion. On this plentiful food supply they thrive in vast num- 

 bers and constitute food for larger animals, the predacious 

 insects, the young of fishes and other carnivores. They 

 constitute a staple fish-food; it has been said (Carman) that 

 no other one genus of insects constitutes as important an 

 item in the food of so large a number of fishes. 



Fig. 228. — The midge Chironomus: i, larva; 2, 

 pupa; 3, adult. 



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