AQUATIC MIDGES AND SOME RELATED INSECTS. 23 



deposit substances that could be used as food. This seems especially possible, because 

 the larvae of Group I are known to eat and replace certain parts of the silk composing 

 the wall of their burrows at irregular intervals. 



The larvae, on the other hand, are known to have the habit of scraping up substances 

 to be eaten directly as food. The author has observed this behavior in the case of well- 

 soaked pieces of cracked corn. These the larvae seemed to have eaten exclusively, for 

 their stomachs were full of the starch grains. The larvae frequently reached out for 

 some distance and unless the fragments were easily moved did not seem to attempt to 

 drag them in. Once a piece of corn was found it was usually eaten out until nothing 

 but the hull remained. 



An examination of the debris at the bottom of the Greencastle (Ind.) troughs 

 showed the greatest number of larvae per square foot yet found, which by count of a 

 smaller area was estimated to be 500 to the foot. Here an abundance of diatoms, in- 

 terspersed with corn and oats brought in the mouths of the horses from a near-by livery 

 stable, formed a layer about an inch and a half in depth. The flowing water and the 

 undulating motion of the larvae kept the conditions suitable to favor the development of 

 diatoms, as was indicated by the great abundance of a relatively few species. The 

 presence of a considerable amount of horse champings did not seem to upset the balance, 

 as a too liberal addition of corn has been found to do in laboratory cultures. Miss 

 Tilbury (19 13) found it possible to rear the larvae of this species from egg to adult on 

 Potamogeion crispus alone. This she grated up and fed to them in small amounts. 



It will be seen from the above observations that Chironomus cayugcB is well suited 

 to experimental culture methods, and it seems probable that the group as a whole is 

 equally hardy. Their large size and overlapping broods offer considerable encourage- 

 ment to the hope that they may sometime be an important factor in fish culture. 



Group IV. — Chironomus braseniae. n. sp., a leaf-eating chironomid. 

 INTRODUCTION. 



While on a lymnological trip to North Spencer, N. Y., the author's attention was 

 called by Dr. Needham to the work of an insect larva that was cutting burrows in the 

 floating leaves of the water shield, Brasenia schreberi, and to a lesser extent in the 

 leaves of the sweet-scented water lily, Castalia odorata. The larvae were found to be 

 those of a midge of the genus Chironomus and apparently an undescribed species, al- 

 though this or a species with similar habits seems to have been observed by workers in 

 several different parts of the country. Mr. Isley, of the U. S. Bureau of Entomology, 

 informs the writer that he has seen larvae of this genus with similar habits in the vicinity 

 of Washington, D. C. Dr. R. H. Pettit has referred to a species which he bred from the 

 leaves of both Nuphar advena and Nymphea odorata in the Wild Gardens, Forest Hill, Mass. 

 He also observed this same species at Pine Lake, Ingham County, Mich. The author has 

 seen specimens from Fair Haven and North Spencer, N. Y. Dr. Pettit's note on an 

 undescribed species published in the first report of the Michigan Academy of Science 

 (1900) is the only reference the writer has found in the literature, however, to a species 

 of Chironomus with similar habits, although the closely related genus of Cricatopus, 

 according to a brjef note by C. W. Johnson published in the Entomological News (vol. 

 80285°— 22 1 



