Insect Study 



311 



perfect wings, it does not grow larger. Many adult insects take very 

 little food, although some continue to eat in order to support life. The 

 adult stage is ordinarily shorter than the larval stage; it seems a part of 

 nature's economic plan that the grown-up insects should live only long 

 enough to lay eggs, and thus secure the continuation of the species. 

 Insects having the four distinct stages in their growth, egg, larva, pupa 

 and adult, are said to undergo complete metamorphosis. 



But not all insects pass through an inactive pupa stage. With some 

 insects, like the grasshoppers, the young, as soon as they are hatched, 

 resemble the adult forms in appearance. These insects, like the larva, 

 shed their skins to accommodate their growth, but they continue to feed 

 and move about actively until the final molt when the perfect insect 

 appears. Such insects are said to have incomplete metamorphosis, 

 which simply means that the form of the body of the adult insect is 

 not greatly different from that of the young; the dragon-flies, crickets, 

 grasshoppers and bugs are of this type. The young of insects with an 

 incomplete metamorphosis are called nymphs instead of larvae. 



A young grasshopper, enlarged. 



The line shows its actual length. 



The adult of the same 

 grasshopper, natural 



size. 



Summary of the Metamorphoses of Insects 



Kinds of Metamorphosis 



I. Complete metamorphosis 



II. Incomplete metamorphosis 



Names of Stages 



Larva. 



Pupa. (The pupa is sometimes 



enclosed in a cocoon.) 

 .Adult or winged insect. 



Rwo- 



Nymph (several stages) . 

 .Adult, or imago. 



Insect brownies; tree-hoppers as seen through a lens. 



