AQUATIC INSECTS 



Fig. 196. — Cases of leptocerids; i, Leptocerus; 

 2, Tricefiodes. 



Triaenodes. — The larva of Tricsnodes swims rapidly about 

 carrying its case (Fig. 196) with it among submerged plants 

 in quiet bays and ponds. The case resembles that of Phi'y- 

 ganea (Fig. 194), but it is smaller and the leaf -fragments are 

 finer and fitted together with more precision. The delicate 

 spiral egg-masses are laid on the under surfaces of lily pads 

 (Fig. 18 and PI. XVII), sometimes containing about two 

 hundred eggs though each is but one-fifth of an inch wide. 

 The adults begin to emerge in the middle of June and the 

 eggs are found from then on through early midsummer. 



Family Odontoceridae. — The larvae of only a single species 

 of this family have been described (Lloyd). 



Fig. 197. — Case of Psilotreta. 



Psilotreta. — Larvae of Psilotreta are found in the riffles of 

 stony brooks. During the winter they crawl over the bottom 

 but in early spring when they are ready to pupate they gather 

 on the sides of stones, fastening their cases (Fig. 197) there in 

 piles. In these piles the cases are always placed parallel to 

 one another with the head ends pointing toward the surface. 

 Length of case, one half inch. 



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