AQUATIO INSECTS IN NEW YORK STATE 209) 
on the bottom in the midst of a very thin layer of silt and veg- 
etable debris covering the white sand. Its loose gelatinous case 
is covered with adherent silt, and takes on the general, protec- 
tive color of the bottom. As is well known, the larvae of the 
larger red species are among the most characteristic bottom 
forms in all our larger and deeper lakes, being usually asso- 
ciated with deep water mollusks (Pisidium) and caddis fly 
larvae. This distribution, the natural abundance of the larvae, 
and the constant succession of generations through the year, 
leaving no period of absence of the larvae from the water, con- 
stitute the claim of these larvae to economic importance. 
The pupae at first are red, but that color is generally quickly 
obscured by the development of the pigment of the adult insect. 
Within a few days at most after the transformation from the 
larva, the pupa rises to the surface and floats there, descending: 
when disturbed, but quickly rising again. Pupae are less uni- 
formly distributed over the surface than are larvae over the 
bottom, for the wind may drive them together in great masses. 
Pupae are often taken in numbers in a surface net in towing; 
larvae are rarely taken so, and then only at night, and in shal- 
low water, for the larvae often leave their retreats at night and 
go swimming considerable distances with figure-of-eight loop- 
ings of the body. 
It will be seen in the table that, with the exception of trout 11, 
every trout that had eaten Chironomus at all had eaten either 
larvae or pupae largely in excess; a large number of one stage, 
few or none of the other. In the light of the differences in hab- 
its of larvae and pupae just stated, this should indicate that 
some of the fish had been feeding chiefly or wholly at the bot- 
tom, others at the surface of the pond. The larger number of 
larvae eaten may indicate either that larvae were more easily 
obtained, or that they were preferred, or that bottom feeding 
was preferred. 
2 Corethra 
This is another form that is common in our northern lakes 
generally. It was not studied at Bone pond, and was collected 
there only by the trout. Corethra plumicornis is 
