AQUATIC INSECTS IN NEW YORK STATE 2111 



larger prey, however. Very frequently in my aquariums, after- 

 the supply of other food has run out, I have found a larva, with 

 another larva of its own species and nearly of its own size, twO' 

 thirds swallowed and one third digested. 



We have but few species of Corethra, and they are much alike^ 

 and should be readily recognized generically in larval and pupal 

 stages by comparison with the figures given on plate 39. 



3 Unknown trichopter larva from bottom of Bone pond 



This is another species that lives outside the line of the shore- 

 vegetation. Just outside that line, on bottoms shallow enough 

 to be reached with a long handled sieve net, Mr Betten found' 

 the cases of the species in great abundance, but they were all 

 empty. He has described the case in bulletin 47, page 572, as- 

 no. 2. 



Because all students of our lake bottoms have reported caddis 

 fly larvae along with Chironomus larvae as a constant part of 

 the fauna, I have thought it desirable to have the structural' 

 characters of this species illustrated as fully as possible in the 

 hope of its recognition by comparison in the future. The only 

 specimens seen were obtained from the trout stomachs, and" 

 were pretty well digested. Some of the cases were fairly well- 

 preserved, but the pupae were so badly disintegrated as to be 

 hardly distinguishable as pupae; the parts of the larvae most 

 strongly chitinized, and the parts most important for the dis- 

 tinguishing of the species were fairly well preserved, and have 

 been used, together with a perfect case collected from the water 

 and apparently belonging to the same species, as a basis for the- 

 figures presented on plate 6. 



The trout swallow the animals case and all, doubtless being 

 unable to get them apart. The case persists after the animal 

 within has been disintegrated, but the sand grains gradually 

 fall off, and the brown, lining tube of silk gradually breaks up^ 

 into fragments. Most of the stomachs contained a little sand^. 

 doubtless derived from this source, and trout nos. 2, 3, 6, 7 and 17 

 contained large quantities loose, in addition to that still on the- 

 walls of the cases remaining. 



