AQUATIC INSECTS 



Fig. 199. — Cases of i, Helicopsyche; 2, Goera; 3, 

 Brachycentrus. 



(Fig. 199, 2) are slightly flattened and like those of several 

 other caddis larvae they have ballast stones glued on each side 

 which keep them from being carried away by the current. In 

 March the cases are fastened down for pupation to exposed 

 stones in the full current, and a pebble placed over the open- 

 ing. The adults emerge through April and May. 



Brachycentrus. — During its early life Brachycentrus (Fig. 

 199, 3) lives in the side waters of brooks actively foraging 

 along the banks, then it moves into mid-channel and attaches 

 one front edge of its case to a stone. It always chooses 

 an exposed place and faces up-current, holding its legs 

 extended upstream like the mayfly Chirotenetes (Fig. 24). 



During its browsing days the larva first lives upon diatoms, 

 and then upon algas, but when about six weeks old it adds to 

 this a diet of mayflies, water-mites, midge larvae, and small 

 crustaceans. Case of full grown larva, one half inch long. 

 The adults emerge late May-June. 



Aquatic Moths — Lepidoptera 



Water caterpillars. — Alost caterpillars are like cats; they 

 walk to the shore but they do not go into the water. Among 



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