LOCUSTS, BUTTERFLIES, BEES, WASPS 161 



intestine begins. The intestine makes one bend and then 

 dilates to form the rectum. 



A locust eats many different kinds of plants, chiefly 

 grasses and forage and grain plants. They are voracious 

 insects and often eat every growing thing in their path. 



How the locust breathes. — The air enters an insect's 

 body through holes along the sides of the abdomen and 

 thorax, and passes into a system of tubes known as tracheae. 

 This is well illustrated by the locust. Figure 94 shows the 

 right side of the abdomen of a locust with the holes called 



Ventral transverse tmchece 



Dorsal longitudinal 



trachecB 



Lateral longitudinal trachea 

 Fig. 100. — Tracheal system of a grasshopper. 



spiracles, one on each side of the first eight segments. Note 

 the two spiracles on the thorax, also. From each spiracle 

 a short trunk runs inward and connects directly with two 

 large tubes that nm lengthwise, one on each side of the body 

 cavity. (Fig. 100). Closely connected with these are two 

 long tubes running along the dorsal side of the body cavity. 

 There are also two shorter and smaller air tubes along the 

 ventral side of a part of the abdomen. All of these mauD 

 tracheae send off smaller tubes that divide and subdivide 

 into smaller and smaller branches which reach every part 

 of the body, even entering the legs and wings to some 

 extent. 

 "The tubes are filled and emptied by a rhythmic, alter- 



herri'^b's zoBl. — 11 



