90 



ZOOLOGY. 



parts incapable of being stretched. At the end of a 

 definite period of time this firm covering is stripped 

 off and replaced by a new investment, soft at first, 



Fig. 62. — The Migratory Grasshopper (^Acrt/dium migrator turn). Larva and adult female. 



but afterwards becoming hard. In this way growth 

 can be effected in spite of the hard integument. 

 Everyone must have noticed at some time or other 

 the moulting of caterpillars. 



Fig. 63 Looper Caterpillar. 



Fig. 64.— False Caterpillar. 



In insects with incomplete metamorphosis the form 

 of the animal alters a little at every moult, becoming 

 more and more like that of the adult insect. In the 

 last moult but one small imperfect wings appear 



