INSTINCT OF INSECTS. 



383 



stance not present when the other nine were constructed, — 

 we are constrained to admit that nothing in the instinct of 

 other animals can be adduced exhibiting similar exquisite- 

 ness : just as we must confess an ordinary loom, however in- 

 geniously contrived, far excelled by one capable of repairing 

 its defects when out of order. 



The examples of this variation and accommodation to cir- 

 cumstances among insects are very numerous; and as pre- 

 senting many interesting facts in their history not before 

 related, I shall not fear wearying you with a pretty copious 

 detail of them, beginning with the more simple. 



It is the instinct of Geotrupes vernalis to roll up pellets of 

 dung, in each of which it deposits one of its eggs ; and in 

 places where it meets with cow or horse-dung only, it is con- 

 stantly under the necessity of having recourse to this process. 

 But in districts where sheep are kept, this beetle wisely saves 

 its labour, and ingeniously avails itself of the pellet-shaped 

 balls ready made to its hands which the excrement of these 

 animals supplies. 1 



A caterpillar described by Bonnet, which from being con- 

 fined 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 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 be- 

 fore the opening. * 2 



The larva of the cabbage-butterfly (Pontia Brassicce), 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, therefore, it previously covers a space of 



1 Sturm, Deutschlands Fauna, i. 27. 



2 (Euvres, il 238. See above, p. 211. 



