104 PROCEEDINGS ENTOMOLOGICAL SOCIETY 



first it was thought that the larvae were attempting to conceal 

 themselves, but it soon became evident that this was not the 

 case. The following morning all except three or four of those 

 , in this beaker were found to be dead, having apparently 

 succumbed to suffocation. 



On the other hand, those placed in the beaker of clear water 

 soon collected a mass of fine debris which they fastened to- 

 gether by means of fine threads, thus constructing a shapeless 

 case within which all concealed themselves. Here they re- 

 mained alive for several weeks, never voluntarily leaving 

 their hiding place, at least during daylight. Only two of these 

 larvae were induced to pupate. The first pupa was observed 

 the morning following collection. It was lying flat on the 

 bottom of the beaker and so remained until the emergence 

 of the adult four days later. When disturbed it would dis- 

 play some feeble movement, but at no time was it active. 

 The second pupa was formed within the above-mentioned 

 case. In neither case was the act of emergence observed. " 



The principal feature of interest in connection with this 

 species is the unusual habitat. Species of Chironomus are 

 known to breed in lakes, sometimes at great depths, in stag- 

 nant pools and ponds, and even in running water, but this is 

 the first instance known to the writer of a species being known 

 to breed in a closed well. The larva is of the type possessing 

 two pairs of blood gills, is blood-red in color, due according 

 to Miall to the presence of hemoglobin, and is thus adapted 

 to living in deep water instead of at the surface. That the 

 larvae in question do in fact live at the bottom of the well 

 is shown by their behavior in the beakers, where they were 

 under almost constant observation for over two months, and 

 were never seen to rise near the surface. This habit of deep 

 living accounts for their being brought up by the pump, 

 the screen of which is near the bottom of the well. 



Specimens of the adults were sent to Prof. 0. A. Johannsen, 

 Orono, Maine, who has kindly identified them as Chironomus 

 dorsalis Meig. 



It is not probable that the presence of these insects in the 

 water has any considerable deleterious effect in itself. Rather 

 is it believed that their presence is an indication of contamina- 

 tion from other sources. Their presence, however, is in no 

 way desirable in water intended for household purposes, and 

 should the habit of breeding in wells become general, it will 

 present a problem of some economic interest. 



Dr. Dyar said that the presence of the larvae in the well was 

 probably induced by the wooden walls, which would furnish 



