THE GOAT MOTH. 
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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 
j 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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