208 NEW i'OEK STATE MUSEUM 



habits. It is quite probable that with pond culture, as with 

 agriculture, when real progress begins it will be necessary to 

 recognize not only species, but also varieties of the more im- 

 portant species.^ 



Notwithstanding the indefiniteness of our knowledge con- 

 cerning Chironomus as a whole, it may be worth while to ven- 

 ture some general observations concerning the habits of the 

 genus, since these will explain some peculiarities of the table.. 

 Among the larvae attributed to the genus there is consider- 

 able diversity of structure, and a very striking range of color. 

 Color differences have led to the distinction " white larvae "■ 

 and " red larvae " in such papers as the one above quoted. The 

 distinction is arbitrary, however, and of very limited applicabil- 

 ity. The range of color is continuous from bright crimson in 

 some of the red larvae to translucent pale yellowish or green- 

 ish in the others. Moreover, all are " white larvae " when 

 newly hatched; and the red color is correlated with a consider- 

 able increase in size without a corresponding development of 

 the tracheal system in the body, and is due to the increase 

 of hemoglobin in the blood plasma. In general, it may be said 

 that the "red larvae" are larger, have a more extensive devel- 

 opment of blood gills, and live in deeper or less well aerated 

 water; the " white larvae," most of which are not Chironomus- 

 in the stricter sense, are as a rule smaller, have little develop- 

 ment of blood gills or of hemoglobin in the blood plasma, and 

 live in rapids, on shore vegetation in shallower, cleaner, better 

 aerated water. 



The Chironomus of the foregoing table is one of the larger 

 species, with larvae of bright red color. Many of them were 

 alive when taken from the trout stomachs, and wriggled about 

 as actively as if just taken from the water. In shore collecting 

 none were found, but a few of their loose, flocculent gelatinous 

 cases were found at the farthest reach of a long handled net 

 (depth 5-6 feet). The species is doubtless a denizen of the deeper 

 water, which is the proper feeding ground of the trout. It lives 



1 Several Bntisli species are characterized in their immature stages and 

 a good general introduction to the study of the biology of the genus is 

 now available in Miall & Hammond's TTie Earlequin Fly, Oxford 1900 



