4-70 INSTINCT OF INSECTS. 



confined in a box was unable to obtain a supply of the 

 bark with which its ordinary instinct directs it to make 

 its cocoon, substituted pieces of paper that were given 

 to it, tied them together with silk, and constructed a 

 very passable cocoon with them. In another instance 

 the same naturalist having opened several cocoons of a 

 moth (Cucullia Verbasci), which are composed of a mix- 

 ture of grains of earth and silk, just after being finished ; 

 the larvae did not repair the injury in the same manner. 

 Some employed both earth and silk ; others contented 

 themselves with spinning a silken veil before the open- 

 ing a . 



The Jarva of the cabbage-butterfly (Pontia Brassica] 

 when about to assume the pupa state, commonly fixes 

 itself to the under-side of the coping of a wall or some 

 similar projection. But the ends of the slender thread 

 which serves for its girth would not adhere firmly to 

 stone or brick, or even wood. In such situations, there- 

 fore, it previously covers a space of 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^ Muscorum and some other species of humble- 

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



a OEuvrcs ii. 238. See above, p. 256. 

 b Apis. * *. e. 2. K. 



