464 HYBERNATION OP INSECTS. 



think it necessary to go further ? We are content to 

 refer to instinct, the retirement of insects into the earth 

 previously to becoming pupae, and the cocoons which 

 they then fabricate ; and why should we not attribute 

 to the same energy, their retreat into appropriate hy- 

 bernacula, and the construction by many species of ha- 

 bitations expressly destined for their winter residence ? 

 The cases are exactly analogous; and the insect knows 

 no more that itshybernaculum is to protect it from too 

 severe a degree of cold during winter, than does the 

 full-fed caterpillar when it enters the earth that it 

 shall emerge a glorious butterfly. 



I am, &c. 



