278 STATES OF INSECTS. 



mock might have been slung, the caterpillar has been di- 

 rected so to place it, that the silken cord that suspends 

 the head is fastened close to the side of the door which it 

 has previously constructed ; and the moth, guided by this 

 fdum ariadneum, at once makes its way out of an apart- 

 ment which, but for this contrivance, might have been to 

 it a labyrinth as inextricable as that of Minos a . 



The mode in which other caterpillars provide for their 

 extrication, when become moths, from their silken co- 

 coons, is not less ingenious. Those ol ? Eriogaster lanestris 

 (of which I have lately said so much,) and others, form 

 oblong cocoons, which, viewed externally, you would at 

 the first glance assert were of one solid piece : but on 

 examining them more narrowly, you perceive one end of 

 them to be a distinct lid, of a size large enough to per- 

 mit the moth to issue out ; and that it is kept in its place 

 by a few slight threads, easily broken by pressure from 

 within b . A few pages back c I mentioned a cocoon formed 

 by the larva of Tortrix prasinana, of the shape of a 

 boat reversed, composed of two inclined walls fastened 

 together at the top and ends. In constructing this cocoon, 

 it firmly glues to each other the top and one end, so as to 

 form an impermeable suture ; but the other end, at which 

 the moth is to issue, though externally it seems as strong 

 as the rest, is merely drawn close by a slender thread or 

 two fastened on the inside, and easily broken from within. 

 And, what is particularly singular in the construction of 

 this ingenious habitation, the sides forming the end last 

 mentioned, though originally requiring force to draw 



a Bonnet, (JZuvr. ii. 207. b Ros. I. iv. 209. t, Ixiii. ccxii. 



c See above, p, 217. 



