INSECTS. 325 



CHAPTER XXXIII. 

 Insects. 



THE general organization of insects has been ex- 

 plained in Chapter XV., in the description of the may- 

 bug. The structure of the wings and of the mouth is 

 the basis of the classification in orders shown on page 

 326. 



Before studying some of the more important repre- 

 sentatives of the class insecta it is well that we should 

 recall the fact that, while a few insects assume their final 

 forms on leaving the egg, most of them pass through 

 several distinct phases between the egg and the perfect 

 creature. 



The egg gives birth to a sort of worm, either with or 

 without legs, and these creatures are called larvae ; when 

 they have legs they are commonly called caterpillars. 

 The larvae of some species closely resemble the perfect 

 insects, the wings only being absent, and these appen- 

 dages are developed after the last casting of the skin ; 

 in such cases the metamorphosis is said to be incom- 

 plete. We have an example in the cockchafer. In a 

 much larger number of species the changes at the vari- 

 ous stages of existence are more remarkable, and it is 

 difficult to find any resemblance between the larvae and 

 the perfect insect ; metamorphosis is complete, and the 

 butterflies furnish us an example. 



The state of chrysalis, pupa, or nymph, as it is vari- 

 ously called, succeeds that of the larva. During this 

 period most insects abstain from all nourishment, and 

 are apparently dead. To protect themselves from the 



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