A STRONG FORTRESS. Ill 



The colouring of this creature varies according to 

 the time of year ; but it may be easily recognised by 

 its form alone, which is very peculiar. 



One of the most remarkable points in the creature 

 is the forked apparatus at the end of the tail, and 

 which frightens people who do not know the habits 

 of the caterpillar. These forks are black externally, 

 and rather stiff, but are only sheaths for two curious 

 rose-coloured tentacles, which are usually kept hidden, 

 but which may be seen by touching the caterpillar 

 with the point of a needle. When the creature is 

 thus irritated, it will protrude these tentacles from 

 their sheath, and will then strike the part that had 

 been touched. 



It is supposed that this apparatus is intended as a 

 kind of whip, wherewith to drive away the ichneumon 

 flies, and other parasites, that inflict such annoyance 

 on many caterpillars. 



"When this caterpillar proceeds to its pupal state, 

 it makes itself a wonderful fortress — not suspended 

 like that of the Tiger-moth, nor hidden in a dark 

 spot ; but it boldly fixes its residence on the exterior 

 of the tree on which it feeds, trusting to its similitude 

 to the bark for concealment, and to the strength of 

 its habitation for safety, even if discovered. 



It is furnished with a gummy substance, some- 

 thing after the manner of the silk of the Tiger-moth ; 

 but instead of spinning that substance into threads, 

 it uses it in the following manner. 



