454' HYBERNATIOxV OF INSECTS. 



escape tlie pain arising from a low temperature that 

 insects bury themselves in their winter quarters. 



In fact, the great source of the confused and unsatis- 

 factory reasoning which has obtained on this subject, is, 

 that no author, as far as my knowledge extends, has kept 

 steadily in view, or indeed has distinctly perceived, the 

 difference between torpidity and hybernation ; or, in 

 other words, between the state in which animals pass the 

 winter, and their selection of a situation in which they 

 may become subject to that state. 



That the torpidity of insects, as well as of other hy- 

 bernating animals, is caused by cold, is unquestionable. 

 However early the period at which a beetle, for exam- 

 ple, takes up its winter quarters, it does not suffer that 

 cessation of the powers of active life which we under- 

 stand by torpidity, until a certain degree of cold has been 

 experienced ; the degree of its torpidity varies with the 

 variations of temperatm'e; and there can be no doubt 

 that, if it were kept during winter from the influence of 

 cold, it would not become torpid at all — at least this has 

 proved the fact with marmots and dormice thus treated ; 

 and the Aphis of the rose {A. Rosce), which becomes tor- 

 pid in winter in the open air *, retains its activity and 

 gives birth to a numerous progeny upon rose trees pre- 

 served in greenhouses and ,warm apartments. 



But, can we, in the same way, regard mere cold as 

 the cause of the hybernation of insects ? Is it wholly 

 owing to this agent, as most writers seem to think — to 

 feelings either of a pleasurable or painful nature pro- 

 duced by it — that jveviouslij to becoming torpid they 

 select or fabricate commodious retreats precisely adapted 

 ' Kyber in Gcrinar's Mag. dcr Enl. ii. 3. 



