OAK-BARK CATERPILLAR, 199 



it proceeds to draw them together in a manner si- 

 milar to that which the leaf-rolhng caterpillars employ 

 in constructing their abodes, by pulling them with 

 silken cords till they bend and converge. Even 

 when the two longest sides are thus joined, there is 

 an opening left at the upper end, which is united in 

 a similar manner. When the whole is finished, it re- 

 quires close inspection to distinguish it from the 

 branch, being formed of the same materials, and 

 having consequently the same colour and gloss. 

 Concealment, indeed, may be supposed, with some 

 justice, to be the final object of the insect in pro- 

 ducing this appearance, the same principle being ex- 

 tensively exemplified in numerous other instances. 



