THE GOAT MOTH. 



13 



the head is of a wedge-like shape, so that the creature can force 

 itself even through hard wood. It feeds entirely upon the 

 substance of the tree in which it takes up its residence, and 

 leaves in its tunnels a considerable amount of debris. As the 

 creature increases in size, its tunnel increases in diameter ; and 

 it is an amusing task to cut up an old and soft-wooded tree, and 

 follow the caterpillar through its manifold windings. 



It lives for some three years in the larval condition, and 

 during the winter it lies dormant in an ingeniously made cocoon, 

 constructed from wood-chips and silken thread, a large store of 

 which can be produced by this caterpillar. Some cocoons are 

 now before me, which I took from a willow tree in Erith marshes. 

 Out of a great number of specimens I have selected four, in 

 order to show the different dimensions of the cocoons. The 

 largest is two inches and a quarter in length, and rather more 

 than an inch in width. In shape it is nearly cylindrical, except 

 at the ends, which are rounded. One of them is intact, but the 

 other has a round hole through which the larva has emerged. 

 It is composed of wood-chips of various sizes, looking like 

 ordinary sawdust, which are loosely, though thickly, fastened 

 upon a silken framework. Near one end of the cocoon the 

 chips are very heavily massed, for what purpose seems doubtful. 

 Rough, however, as is the exterior of the cocoon, the inside is 

 quite smooth and soft, not unlike the interior of the tube made 

 by the trapdoor spider. 



The smallest cocoon is barely an inch in length, and is made 

 of much smaller chips, fastened together so strongly that the 

 cocoon retains its cylindrical form when handled, whereas the 

 larger specimen is so loosely made that it collapses under the 

 least pressure. The other two are intermediate in point of size, 

 but precisely similar in point of construction. Besides them 

 there is a specimen of the cocoon in which the creature undergoes 

 its last change. This is of far stronger texture than either of 

 the others, being quite hard, like papier-mache, and dark and 

 polished within. 



Generally, just before the moth emerges, the chrysalis works 

 itself along, so that it partially projects from the hole, thus 



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