39 



ii. Root feeders ; Hepialns, Xi/lophasia monoiilypha, certain 



Agrotids, etc. 

 iii. Lichen feeders ; Litliodidae, and the genera Bri/ophila, 



Cleova, etc. 

 iv. Many grass feeders ; Satyridae, tlesperiidae, many Lencan- 



iidae, etc. 

 V. Many polyphagous species feeding on low plants that 

 remain green throughout the winter. 

 Pictet (17) has shown that of Lepidopterous larvae those that 

 feed more or less throughout the winter respond very much more 

 readily to artificial warmth than do those that feed only on 

 deciduous plants, and into whose life-cycle there necessarily enters 

 at some period of their existence a prolonged period of rest. In 

 the case of Lasiocamjia quercm for example he found that even if 

 the larvtie were kept at a warm temperature they nevertheless 

 hibernated as under normal conditions. 



It was possible to shorten this resting period to a certain 

 degree, but in this case the pupal resting period was correspond- 

 ingly prolonged, so that the time of emergence of the resulting 

 imago was not altered. So also in the case of species that 

 hibernate in the egg stage, if they could be induced to hatch 

 before their time the subsequent larval period was correspondingly 

 prolonged. Possibly Mr. Newman or other of our members who 

 have experience in forcing pup^e to any extent would give us 

 their conclusions as to how far the species that respond readily to 

 forcing are feeders upon foliage that persists throughout the 

 winter, and how far those that do not so respond are feeders upon 

 deciduous foliage. 



If we consider briefly the different orders of insects as regards 

 the way in which they pass the winter, we at once find ourselves 

 handicapped by lack of data concerning almost all the orders except 

 Lepidoptera. At any rate the Odonata (15) would appear to be one 

 in which in this country we can find no hibernating imagines,* 

 probably all over-wintering as nymphs. As, however, these are 

 aquatic, long-lived, and predaceous, that the nymph should 

 hibernate is almost a foregone conclusion. They are, however, 

 sluggish, and feed very little if at all during the winter. 



The grasshoppers (14) are predominantly summer or autumn 

 insects, yet at least one genus [Tetrix) is known to hibernate in the 



* Mr. Lucas informs me that on the Continent Sympyaia fusca legularly 

 hibernates. 



