LEPIDOP TERA . 1 49 



themselves from them. Sometimes the threads do not break at once. 

 Then the animal recommences its revolutions in an opposite direction, 

 and this time it is almost certain to succeed. Reaumur, however, 

 saw a chrysalis which, after having tired itself in vain in its endeavours 

 to get entirely free of its old skin, despairing of ever being able to 

 manage it, abandoned it where it was so solidly fixed. We represent 

 (Fig. 107), rather magnified, the chrysalis arrived at its final state, and 

 suspended to a branch of a tree by a network of silk.* 



We come now to the mode of suspension employed by those 

 caterpillars, which, after having fixed themselves by the tail, strengthen 

 the support by means of a small silk cord passed round their body. 



It is again to Reaumur, that indefatigable observer of the habits 

 of insects, that we go for the details of this manner of suspension. 

 According to Reaumur, these caterpillars make and put on this belt 

 in three different ways. But of these three ways the simplest, and 

 the least liable to meet with accident, is that employed by the larva 

 of the Cabbage Butterfly (Pieris brassicce). When the time for its 

 metamorphosis is only a few days distant, one may observe this 

 caterpillar engaged in stretching threads on different parts of the case 

 in which it is confined. It then chooses a spot, which it covers 

 entirely with threads, some more compact than the others, and 

 disposed in layers, which cross each other in different directions. 

 These threads form a thin white cloth, against which the belly of the 

 caterpillar and later that of the chrysalis are applied. Very soon we 

 see a small hillock of silk rising. The caterpillar hooks itself on to 

 this by the claws of its hinder feet, and sets to work to secure itself. 



To understand this process, it suffices to know that after having 

 lengthened its body to a certain point, this caterpillar can turn back 

 its head on to its back, and reach to the fifth ring, having its three 

 pairs of true legs in the air. But without putting the caterpillar into 

 such an unnatural position, let us take it in a position in which it is 

 simply bent sideways in such a manner that its head, with the thread- 

 spinning apparatus, which is below, can be applied opposite and 

 pretty near to one of the legs belonging to the first pair of mem- 

 branous legs. Our caterpillar begins by fixing on this point a 

 thread, which is the first of those that are intended to tie it up 

 securely. 



" This thread," says the illustrious author of the " Memoires pour 

 servir a 1'Histoire des Insectes," must pass over the caterpillar's body ? 



* It has been remarked that only those whose continuance in the pupal state is 

 short, undergo their metamorphosis in this apparently inconvenient position. ED. 



