INSTINCT OF INSJ;CTS. 475 



avails itself of the pellet-shaped balls ready made to its 

 hands which the excrement of these animals supplies*. 

 A caterpillar described by Bonnet, which from being 

 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 {Noctua Verbasci, F.), which are composed of u 

 mixture 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 opening**. 



The larva of the cabbage-butterfly (Papilio Bras- 

 sicce, L.) when about to assume the pupa state, com- 

 monly 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, therefore, 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 rio preparatory web. 



* 5tarm, Deulschland'' s Fauna,\. 27. " (Euvrcs,u. 238. Sec above, p. 260. 



