GOAT MOTH. 207 



ate could have attained so very artificial a condition as to endure 

 this repulsive creature, much less to consider it as a dainty. 



It grows with wonderful rapidity, being when it has reached its 

 full size seventy-two thousand times heavier than when it was 

 hatched ; its segments are deeply marked, and in color it is of a 

 mahogany-red above, and yellowish below. The whole surface is 

 smooth and polished, and, as may be presumed, considering the 

 life which it leads, its muscular strength is enormous. Not only 

 are the large and trenchant jaws extremely thick and strong, but 

 the development of muscle is singularly great ; and the head is 

 of a wedge-like shape, so that the crea,ture 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, con- 

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

 can be produced by this caterpillar. Several cocoons are now be- 

 fore 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. Eough, however, as is the exterior of 

 the cocoon,. the inside is quite smooth and soft, not unlike the in- 

 terior of the tube made by the trap-door 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 speci- 

 men is so loosely made that it collapses under the least pressure. 

 The other two are intermediate in point of size, but precisely sim- 

 ilar in point of construction. Besides them there is a specimen 

 of the cocoon in which the creature undergoes its last change. 



