THE CANADIAN ENTOMOLOGIST. 79 



PRACTICAL AND POPULAR ENTOMOLOGY.— No. 3. 

 How DO Insects Pass the Winter? 



BY JAMES FLETCHER, OTTAWA. 



There are few things in nature quite so remarkable as tlie liiberna- 

 tion of insects and animals in a torpid condition. That life should siill 

 persist when animationis reduced so low, as must necessarily be the case, 

 with these small creatures in close contact with frozen substances or even 

 imbedded in solid ice, would be quite incredible, were there not so many 

 instances which can be examined by those who wish to do so, every day 

 throughout our long and cold winters. In fact, it may be said that the 

 intensity of cold has little or no effect upon insects which have prepared 

 themselves naturally to pass through their long winter sleep, and the 

 remarkable thing is that however low the thermometer may drop, if the 

 insect is in a healthy condition, it never actually freezes in the sense of 

 becoming hard and brittle. This, however, will take place if an insect 

 be disturbed and taken from the place where it had prepared itself for 

 winter, and such insects, if they do actually freeze, seldom or never revive. 

 If they do, they are, as a rule, seriously or fatally crippled. The coverings 

 made by some insects for their protection during the winter are sometimes 

 surprisingly slight, but are sufficient for their needs. 



Anyone wishing to investigate this interesting subject can find 

 ample opportunity, for there is no time in the whoje year when studies in 

 the lives of insects may not be carried on, and, not only will this work be one 

 of great fascination, but the exact knowledge as to the manner and stage in 

 which any species passes the winter may be of great value in suggesting a 

 method of preventing injury by a destructive crop enemy, or in protecting 

 or even introducing from a distant country a beneficial parasite. In the 

 north the long period of inactivity in which insects live through the winter 

 is known as hibernation, and there is a corresponding season in southern 

 arid regions known as aestivation, in which also animation is to a large 

 measure suspended during the inhospitable season when all vegetation is 

 also at rest owing to drought and lack of moisture. An insect may pass 

 through these periods in any of its stages of development — as an egg, a 

 larva, a pupa, or in the perfectly develojJed form. In almost every 

 instance each species of insect has its own special habit in this respect 

 Full details of the life-histories, with the duration of the stages, is lacking 

 with regard to many of our commonest and most destructive pests. 'I'his 

 information, however, is of great importance and presents a very wide and 



March, 1905. 



