32 



the winter in the egg stage and the early spring insects that 

 hibernate as pupae, we will consider only those that truly hibernate 

 in the perfect state. Here, again, we find that this period of 

 hibernation can intervene early or late in the stage of the insect's 

 life, I.e., the insect may hibernate comparatively soon after emerging 

 from the pupa, in any case before the great business of life — mating 

 and reproduction — has begun, or mating may take place before 

 hibernation. In the former case, of course, both sexes hibernate, 

 and mating takes place in the spring. This is the case with most, 

 if not all, of our hibernating butterflies. In the latter case, there 

 being no further need for the (J J , these die off before winter, and 

 only the impregnated ? $ survive. Probably the best known 

 instance of this is found in the Hymenoptera, in the Wasps and 

 Bumble Bees. 



There is, as mentioned before, great diversity also in the depth 

 of this winter sleep. Some species, Aijlais iirticae, for example, 

 very early take up their winter quarters, and though restless for a 

 while, and apt to move about in bright warm weather, usually sleep 

 undisturbed until the arrival of spring. Other species are much 

 more restless, and easily waked by a warm day. Pi/rameis atalanta 

 is on the wing very much later than most of the Vanessids (it was 

 exhibited at our meeting on November 11th last, and probably 

 remained lively for some time later than that) and is notoriously a 

 bad hibernator. Mr. Newman has told us that it is easy enough to 

 keep the species alive through the winter by keeping it warm and 

 feeding it at intervals, but in natural conditions there is some doubt 

 as to whether it ever really succeeds in surviving the winter, except 

 perhaps in Cornwall and the Scilly Islands, where the climate is 

 sufficiently mild to allow of it finding food throughout the winter. 

 Possibly it is so exceptionally in other parts of the country, but 

 on the other hand Mr. Newman suggests that the individuals occa- 

 sionally seen during the winter are in reality only very late emer- 

 gences. The species certainly belongs to more southern climes than 

 our own, where the winters are sufficiently bright and mild to allow 

 of its survival without entering upon a true period of hibernation, 

 so that when it migrates to our latitudes it has not acquired the 

 capacity of standing prolonged cold and fasting. Pytameis c.ardid 

 in Egypt is said to be on the wing throughout the year with a con- 

 tinuous succession of broods. 



Quite a number of tbese insects that hibernate in the perfect 

 state show a marked partiality for human habitations as a place of 



