CATERPILLARS 



layer, and the caterpillar is out of sorts at every 

 moult. There seem to be serious breathing diffi- 

 culties, and there is something like inflammation. 

 The moult is a serious business, and often ends 

 fatally. 



The Pupa or Chrysalis 



After the caterpillar has reached its limit of 

 growth it passes into a resting phase, which is often 

 prolonged for many months. It becomes a pupa, 

 nymph, or chrysalis, and undergoes the great 

 change, which is always called the metamorphosis. 

 In many butterflies and some small moths, the 

 larva fastens itself by its tail to a twig ; in many 

 other cases it suspends itself by a silken thread ; 

 some hide between two leaves fastened together 

 by silk ; many burrow beneath the ground ; most 

 moths make some sort of cocoon or shelter, which 

 may be of pure silk neatly wound, or of silk mixed 

 with hair and all manner of external things such 

 as pieces of leaf, bark, moss, and lichen, and even 

 grains of earth. These cocoons are usually con- 

 structed in sheltered corners, and are often very 

 inconspicuous. The finest pupa-cases are surely 

 those which are spun of silk (in most moths), 

 and the making of them in a few days shows great 

 internal activity on the part of the silk glands, 

 and also great muscular activity on the part of a 

 creature that is about to fall into sleep. The long 

 thread of silk is spun into a well-made sleeping sack 

 by persistent movements of the head, and this may 

 require hundreds of thousands of movements. 



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