AQUATIC INSECTS IN NEW YORK STATE 211 



larger prey, liowever. Very frequently in my aquariums, after 

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

 another larva of its own siiecies 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 

 v.'ithin 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. 



