112 A STRONG FORTRESS. 



Biting little chips of wood from the bark of the 

 tree, the caterpillar glues them together with this 

 natural cement ; and so builds an arched house for 

 itself, much about the size and shape of half a walnut- 

 shell. So strongly compacted is this residence, that 

 rain and wind have no effect on it, and a penknife 

 does not find an easy entrance. 



One or two of these caterpillars which I brought 

 home modified their dwellings in a curious manner. 

 One of them nibbled to pieces a portion of a card- 

 board box, and so made a kind of papier-mache 

 house ; while others, who were placed under a glass 

 tumbler, and upon a stone surface, simply made 

 their house of the hardened gum. In this state, it 

 appeared as if it had been made of thin horn, and 

 was so transparent that the chrysalis could be seen 

 through the walls. 



The caterpillar is common enough, and may be 

 found on the willow or poplar. And a sharp eye will 

 soon learn to detect the winter house, which to an 

 unpractised eye looks as if it were merely a natural 

 excrescence on the bark. 



If one of these habitations is found, the best 

 mode of removing it is to avoid touching the dwell- 

 ing itself, but to cut away the bark round it ; and 

 then, by inserting the point of a stout knife, gently 

 raise up the house, together with the bark on which 

 it is placed. This is one of the modes by which an 

 entomologist may find employment even during the 



