TYPICAL INSECTS 



189 



the moulting in some secluded or protected place. The soft 

 skin allows the body to expand, but it soon hardens into 

 chitin on the outside. The insect then proceeds to eat, and 

 grows as long as its coat will stretch, when the moulting again 

 takes place. 



After several of the first moults fleshy pads begin to be 

 noticeable on the shoulders. These grow with each succes- 

 sive moult, and at 

 the last they are 

 exposed and in- 

 flated with air and 

 blood, and spread 

 out into wings.' 



Insects are clas- 

 sified chiefly ac- 

 cording to the 

 structure of their 

 wings and mouth-parts. Thus the locust, grasshopper, and 

 cricket belong to the OrtJioptera, or straight-winged group, so 

 named on account of the narrow and straight fore-wings. 

 There are about nineteen orders of insects, only six or seven 

 of which need be referred to in nature-study. A typical insect 

 of each of these orders, except the one already described, will 

 be now considered: 



Dragon-flies or Darning-needles are .characterized by a long 

 slender body, lwo pairs of narrow, net-veined wings always 

 extended horizontally from the body, and enormous com- 

 poimd eyes. They are among the best flyers, flitting nimbly 

 in search of insects to devour. They are sometimes called 

 mosquito hawks, because of their predatory habits. Often 



^ For destructive effects of the locust, see pages 222-223. 



Fig. 4S. Dragon-fly. 



