HISTORY OF INSECTS. 43 



its course towards the tail, devouring all the fat and 

 muscular parts not absolutely essential to motion 

 and life ; and, by the time the caterpillar of the 

 moth is full grown, and changes to a chrysalis, 

 the maggot of the ichneumon is full grown also, 

 and occupies more than half of its interior. 



132. It is worthy of remark, that this maggot 

 thus inhabiting for weeks the body of a living 

 caterpillar, and devouring its living flesh, always 

 instinctively avoids those parts which are essen- 

 tial to life, as though aware that the cessation of 

 life in the caterpillar would ensure its own death, 

 as it could not subsist on the putrifying carcase. 



133. After laying quiescent for many days, 

 and often weeks, and sometimes through the 

 whole winter, the skin of the maggot is thrown 

 off, and it becomes a chrysalis, exhibiting very 

 exactly the shape and appearance of the future 

 fly ; the antennae and legs being placed before it, 

 the wings small, and folded by its side, and the 

 ovipositor being turned up a little over its back. 



134. The chrysalis is without motion, and 

 much resembles that of the bee : in both instances 

 the limbs are quite distinct from the body, and 

 not united with it in a hard crustaceous case, as 

 is the case in the chrysalis of the silk -worm : 

 this kind of chrysalis is said to be necromor- 

 phous {pupa necromorpha), from its resemblance 

 to the perfect insect, with its limbs neatly arranged, 

 and motionless, as in death. 



