Insecta. 5 



time. So we can see the fitness of having the flying wings 

 folded compactly and placed close to the sides and guarded. 

 The wings are kept from mutilation, and the whole insect 

 is much less conspicuous than he would be with the wings 

 outspread. Some grasshoppers fly high in the air and 

 travel long distances. 



Respiration in the Grasshopper. The spiracles are 

 shown in Fig. I ; two pairs of thoracic and eight pairs 

 of abdominal openings. From these spiracles, tubes, 



FIG. 3. CROSS SECTION OF INSECT. 



a = Digestive Tube. 



called tracheae, run inward to a trachea extending length- 

 wise on each side of the body. There is also a pair of 

 dorsal and a pair of ventral air tubes. There are, then, 

 six air tubes running lengthwise, in communication with 

 the outside air through the spiracles, and connected with 

 each other by branches. From these main tubes branches 

 extend which subdivide, finely permeating every part of 

 the body, even, to a limited extent, the legs and the larger 

 veins of the wings (see Figs. 3 and 4). In addition to the 

 air tubes there are two rows of air sacs, which add to the 



