82 FIRST BOOK OF ZOOLOGY. 



till finally, on the last moult, it attains the size and features 

 of the mature insect. And even in this growth, so unlike 

 the moth and butterfly, the terms larva and pupa are applied 

 to certain stages of its history. 



The foregoing figure represents the egg and successive 

 stages of the chinch-bug, an insect which has been so de- 

 structive to various crops in the West. The figures are all 

 enlarged ; the little line at the lower left-hand side of each 

 figure represents the natural size. 



Y8. Many insects, as the beetles, flies, moths, butterflies, 

 bees, and wasps, pass through complete and distinct changes 

 from their early condition to maturity, as above described. 

 Other insects, as the grasshoppers, crickets, roaches, and 

 bugs, hatch out from the egg, as little six-footed insects, 

 and not as worms, and in their growth do not pass through 

 an inactive pupa or chrysalis stage, but slowly acquire wings, 

 and ultimately attain full growth as above stated. Hence 

 these changes are not so completely defined as the changes in 

 the insects first mentioned. For this reason the term com- 

 plete metamorphosis is used to define the mode of growth of 

 the beetles, flies, and other insects having a similar mode of 

 growth; while the term incomplete metamorphosis defines 

 the mode of growth of the grasshoppers, crickets, and others. 



79. Many of the larvae of insects look like worms so 

 much so, indeed, that they are commonly called worms, such 

 as cut-worms, canker-worms, currant-worms, and the like. 

 The pupils have learned that these are not true worms, but 

 only the larval condition of certain insects. 



