384 



INSTINCT OF INSECTS. 



about an inch long and half an inch broad with a web of silk, 

 and to this extensive base its girth can be securely fastened. 

 That this proceeding, however, is not the result of a blind 

 unaccommodating instinct seems proved by a fact which has 

 come under my own observation. Having fed some of these 

 larvae in a box covered by a piece of muslin, they attached 

 themselves to this covering ; but as its texture afforded a firm 

 hold to their girth, they span no preparatory web. 



Bombus 1 Muscorum, and some other species of humble-bees, 

 cover their nests with a roof of moss. M. P. Huber having 

 placed a nest of the former under a bell-glass, he stuffed the 

 interstices between its bottom and the irregular surface on 

 which it rested with a linen cloth. This cloth, the bees, 

 finding themselves in a situation where no moss was to be 

 had, tore thread from thread, carded it with their feet into a 

 felted mass, and applied it to the same purpose as moss, for 

 which it was nearly as well adapted. Some other humble- 

 bees tore the cover of a book with which he had closed the 

 top of the box that contained them, and made use of the de- 

 tached morsels in covering their nest. 2 



The larva of Cossus ligniperda, which feeds in the interior 

 of trees, previously to fabricating a cocoon and assuming the 

 pupa state, forms for the egress of the future moth a cylin- 

 drical orifice, except when it finds a suitable hole ready made. 

 When the moth is about to appear, the chrysalis with its 

 anterior end forces an opening in the cocoon. If the orifice 

 in the tree has been formed by itself, in which case it exactly 

 fits its body, it entirely quits the cocoon, and pushes itself 

 half way out of the hole, where it remains secure from falling 

 until the moth is disclosed. But if the orifice, having been 

 adopted, be larger than it ought to have been, and thus not 

 capable of supporting the pupa in this position, the provident 

 insect pushes itself only half way out of the cocoon, which 

 thus serves for the support which in the former case the wood 

 itself afforded. 3 



. The variations in the procedures of the larva of a little 

 moth described by Eeaumur, whose habitation has been be- 



i Apis. * *. e. 2. K. 



3 Lyonet, Traite Anatomique, &c. 16. 



2 Linn. Trans, vi. 254. 



