20 BULLETIN OF THE BUREAU OF FISHERIES. 



quoted above, on the method of collecting particles in the construction of their tubes 

 seemed to be related phenomena. 



Perhaps the most remarkable change in the behavior of these larvae was that exhib- 

 ited by a specimen which, after living a week in quiet water, suddenly found its food 

 swept out of reach by a current. This larva in less than 1 5 minutes raked away a part 

 of the rim that it had spun between the radiating arms and after reinforcing these out- 

 rakers spun a web upon them. The current was set up by a pipette operated by hand, 

 and gave a very satisfactory means of testing the reactions of the larva, for the strength 

 and direction of the current could be changed at will. A complete reversal in the direc- 

 tion of the current seemed to alter the behavior of the larva not at all in regard to its 

 web or any other observed activity. 



It would seem feasible to demonstrate the behavior of this larva in such a special 

 lantern slide as recommended for this purpose with Chironomus lobijerus. The larvae, 

 while sensitive to a jar, do not seem to notice the light particularly, and the adhesive 

 nature of the silk makes it possible to use powdered carmine or India ink to make the 

 strands visible. The current recommended to keep the temperature down could be 

 adjusted to answer for the natural flow of a stream. 



Group III. — Chironomus cayugae Johannsen. 



This group is based upon a recently described species which, so far as can be judged 

 from direct observation as well as indirect references, will prove to be one of the most 

 widely distributed species of the family. It is on this account, as well as upon its 

 unique habit of living in watering troughs where it is easily accessible, that Chironomus 

 cayugcB Johannsen has been selected for the purposes of this study. It is a type of a 

 very large group which is included in Goetghebuer's first group and characterized by 

 the presence of two pairs of branchial filaments on the eleventh segment, a thickened 

 oval area on the labrum, an epipharyngeal comb composed of a row of regular teeth, 

 antennae with five segments, and the pupa without spinose protuberances on the abdom- 

 inal segments. The division includes most of the bigger red chironomid larva? and is 

 probably of greater economic importance than any other group in the family. At this 

 point it may be of interest to recall that most, if not all, of the species of Group I under 

 stress of circumstances adopt the habitat and behavior of this group. 



HABITAT. 



These larvae are fitted by their extra branchial filaments and red blood for life in 

 the debris at the bottom of lakes, ponds, and stagnant pools. The larva? of the species 

 selected as the type, while living in various other habitats, are especially common in 

 horse troughs, having been taken by the author from troughs in Orrington, Me. ; Woods 

 Hole, Mass.; Ithaca, N. Y. ; Dayton, Ohio; Greencastle, Ind. ; Evanston, 111.; and Mil- 

 waukee, Wis. The troughs most carefully studied are those in Woods Hole, Mass., 

 Ithaca, N. Y., and Greencastle, Ind. In none of these troughs was the author able to 

 find any other species belonging to this group represented, and it seems that by some 

 special adaptation this species has succeeded in adjusting itself to conditions different 

 from those common to the group. It is also found associated with Chironomus decorus 

 and others in the debris at the bottoms of larger bodies of water, and it is obvious that it 



