hungerford: aquatic hemiptera. 27 



and no water bugs came forth in the pool transplanted in the 

 laboratory. Thus the "Cattail Pool" comes in the category of 

 the temporary pools that provide range for a spring generation 

 of bugs, but afford no permanent abiding place for this nur- 

 tured population. 



A Permanent Pool. 



The writer is unable to say what has been the past history 

 of Bool's Backwater at Ithaca, New York, but from the topog- 

 raphy of its location and the prevailing climate he believes 

 it to be more or less permanent in its nature. 



The chief interest in this pool was the presence of the over- 

 wintering fourth instar nymphs of Pahnocorixa buenoi in large 

 numbers. There were some other corixids but not in confusing 

 numbers, and the place was chosen to follow the development 

 of the P. buenoi in nature. 



Near the upper end of this Backwater there was a little 

 shallow pool connected by a narrow neck of water to the main 

 body during normal times. A constant stream of fresh w^ater 

 came into the main body near by, but made connection with 

 this little pool only in times of high water. The nymphs of 

 Palmocorixa were here by hundreds. Twenty-three were 

 counted as they foraged in a space two square inches in extent. 

 Under the life history of Palmocorixa will be found the ad- 

 vancement of the development of these bugs. 



April 19 the Arctocorixa alteniata were mating while the 

 P. buenoi were still in the stage in which they overwintered. 



May 9 a wind from the northwest backed the water up so 

 that the little pool was broadly connected with both the Back- 

 water and the Bool's brook. Yet when it was examined the 

 boatmen were seen upon their former foraging grounds though 

 the shore line was several feet beyond the normal. May 11 

 the water was backed to its former level again. Toward the 

 last of the month the little pool was obliterated by high water 

 for several hours at a time but without changing the population 

 to any great extent. Polliw^ogs and minnows invaded the pool 

 in early June, and there was some concern as to the effect the 

 latter would have upon the corixid nymphs which were now 

 attaining the adult state. June 8 the water was two feet higher 

 than usual, and for the next week the shore line was six feet 

 out from the normal. The grass along the east bank of the 

 Backwater was submerged and came to be slime coated with 



