HABITATIONS OF INSECTS. 457 



A third description of larvae, chiefly of the two lepi- 

 dopterous genera Tortrix and Tinea, form into conve- 

 nient habitations the leaves of the plants on which they 

 feed. Some of these merely connect together with a few 

 silken threads several leaves so as to form an irregular 

 packet, in the centre of which the little hermit lives. 

 Others confine themselves to a single leaf, of which they 

 simply fold one part over the other. A third description 

 form and inhabit a sort of roll, by some species made 

 cylindrical, by others conical, resembling the papers 

 into which grocers put their sugar, and as accurately 

 constructed, only there is an opening left at the smaller 

 extremity for the egress of the insect in case of need. If 

 you were to see one of these rolls, you would immediately 

 ask by what mechanism it could possibly be made — how 

 an insect without fingers could contrive to bend a leaf 

 into a roll, and to keep it in that form until fastened with 

 the silk which holds it together ? The following is the 

 operation. The little caterpillar first fixes a series of 

 silken cables from one side of the leaf to the other. She 

 next pulls at these cables with her feet ; and when she 

 has forced the sides to approach, she fastens them toge- 

 ther with shorter threads of silk. If the insect finds that 

 one of the larger nerves of the leaf is so strong as to re- 

 sist her efforts, she weakens it by gnawing it here and 

 there half through. What engineer could act more sa- 

 gaciously ? — To form one of the conical or horn-shaped 

 rolls, which are not composed of a whole leaf, but of a 

 lono- triangular portion cut out of the edge, some other 

 manoeuvres are requisite. Placing herself upon the leaf, 

 the caterpillar cuts out with her jaws the piece which i& 



