234 



THE INSECTS 



life history in common, yet each differs somewhat from the other 

 orders. The characters which all the groups contain in common 

 give us a working definition of an insect. 



One of the most common insects in the United States is the locust 

 or grasshopper, as it is commonly called. The study of a living 

 specimen (or if it cannot be obtained, a dead locust) will, better 

 than any other insect, give us insight into the structure and life 

 processes of this great group. 



The Locust (Red-legged Grasshopper). — The segmented body 

 is divided into a Jiead, a middle portion (the thorax), and a pos- 

 terior part, the abdomen. 

 The legs, six in number, 

 and two pairs of wings 

 are attached to the thorax. 

 The animal lives a rather 

 active life in the fields, 

 the hind pair of legs be- 

 ing adapted by shape, 

 position, and in structure 

 for leaping. Careful ex- 

 amination of the foot of 

 the animal shows a num- 

 ber of tiny hooks and pads, by means of which the foot is fitted 

 for chnging to the swaying grass stalks. 



Wings. — The membranelike wings, when spread out, show 

 differences in structure. Notice the many veins. The outer pair, 

 strong and narrower than the inner pair, serve to protect the inner 

 wings, used for flying, which when at rest fold up like a fan. The 

 animal, when in its natural habitat, is nearly the color of the grass 

 on which it lives. The tough exoskeleton covering the body is 

 formed largely of chitin, a substance somewhat like that which 

 forms the horns of a cow. 



Thorax. — Three segments form the thorax, each bearing a pair of 

 jointed legs, the two posterior segments bearing wings also. 



The Abdomen. — The segmented abdomen does not bear ap- 

 pendages, but at the posterior end of the abdomen of the female 

 are found paired movable pieces which together form the egg layer 

 or ovipositor. The male grasshopper has a rounded abdomen- 



Locust (lubber grasshopper) : AB, abdomen; 

 ANT, antennae; B, eye; M, mouth; P, pads 

 on feet; T, thorax; OV, ovipositor. 



