142 College of Forestry 
the curve showing numerical abundance soars upward and 
continues rising until the onset of cold weather. _ It is not 
known exactly what would be the course of the curve fol- 
lowing the first heavy frost, but there would doubtless be a 
very rapid drop as the wasps and bees sought hibernation 
quarters. 
One interesting observation regarding the seasonal distri- 
bution of several of the lepturids especially, is apparent both 
in the table and in the curve. This is the fact that all of 
the late summer lepturids showed a rapid decrease in num- 
bers after August 17, 1917. At this date the spireea blos- 
soms were only just beginning to wane and several of the 
lepturids as Leptura proxima and L. canadensis were still 
at their maximum and UL. cordifera and Typocerus velutinus 
were but little below their highest numbers. Yet by the 
following week L. proxima had nearly disappeared and there 
was a very striking decrease in all of the lepturids. This 
rapid drop in numbers then occurred in 1917 before any 
frost and was out of all proportion to the decrease in spirzea 
blossoms. A careful search was made upon the blossoms of 
other plants, and while the various Vespide and Bombide 
and beetles such as Chaulignathus pennsylvanicus were pres- 
ent there in ever-increasing numbers no specimen of lep- 
turids were found. It apparently is a case where insects cease 
feeding on the approach of cold weather but a considerable 
time before killing frosts occur. In the cases of insects 
which hibernate either as adults or as immature forms such 
cessation of feeding before the fall frosts might be spoken 
of as an adaptive response, as it seems to be generally under- 
stood that insects are better able to hibernate at low tem- 
perature when the digestive processes have ceased some time 
and the alimentary canal has been entirely emptied of food 
and waste materials. The species in question, however, 
doubtless never hibernates in the adult condition, and it is 
believed that the response to the cool nights which herald 
the approaching frosts results in cessation of feeding and | 
more prompt ovipositing on the part of the adults already 
out. It is likely also that the cool nights react upon the 
