HABITS AND STRUCTURE OF INSECTS. 89 



which they breathe in through openings in the hinder part 

 of the body. Changes soon take place by which they as- 

 sume the pupa state, and at this time they no longer breathe 

 through the hinder portion of the body, but through two 

 tubes on the back of the thorax. Finally, the pupal skin cracks 

 open, and out crawls the perfect mosquito, for a while rest- 

 ing on the empty pupal case which floats in the water like 

 a raft, and the insect remains supported in this way till the 

 wings become fully expanded and dry, when it flies away. 



CHAPTEK XII. 



HABITS AND STRUCTURE OF INSECTS (CONTINUED). 



84. IN certain groups of insects the young hatches from 

 the egg, not as a caterpillar, but as a little insect having the 

 body divided into three regions, possessing three pairs of 

 jointed legs, and looking very much like the mature insect, 

 except that it is very much smaller and has no wings. 



FIG. 87. YOUNG GRASSHOPPEB. w, Wing just appearing. 



In the grasshopper, for example, the animal does not pass 

 through a series of abrupt changes, but the creature comes 

 from the egg with the general proportion of the adult insect, 



