THE GRASSHOPPER 



19 



one. At each molt the shape of the body changes and the 

 wings, which soon appear, grow larger, until finally the adult 

 condition is reached (Fig. 6, 6). The changes that occur 'during 

 this period of growth constitute what we know as metamorpho- 

 sis, and the young in the case of the grasshopper is known as a 

 nymph. 



Metamorphosis. — The development of the insect within the 

 egg, a study called embryology, is too complex to be considered 

 here, but we can discuss with profit the growth of the young 



Fig. 6. — Six successive stages in the metamorphosis of a grasshopper. 

 (After Emerton.) 



after they hatch and the changes that take place from this time 

 until the adult condition is reached. 



A few wingless insects (Aptera) emerge from the egg in the 

 form of the adults and do not change much, except in size, 

 throughout life. Another larger group, of which the grass- 

 hopper is an excellent example (Fig. 6), hatch as nymphs, re- 

 sembling their parents in general form, but thereafter undergo 

 various changes until they have reached their full size. This is 

 direct metamorphosis, the term direct referring to the fact that 

 there are no interruptions due to resting periods, but the insects 

 are active throughout life. The majority of insects, however, 



