32 



ARTHROPODA 



conspicuous, but they do not serve for flight till after the 

 last molt, when the insect is said to have completed its 

 transformation from the nymph to the adult state. In 

 most regions the mature insects may be found in grassy 

 fields from July till frost appears. 



External Features. The food of the locusts is almost 

 any kind of green herbs, which they bite off with a pair of 

 hard lateral moving mandibles. 

 An examination of the mouth 

 region shows an upper lip or 

 labrum covering the front side 

 of the mandibles, which are 

 easily recognized by their hard- 

 ness and serrated inner mar- 

 gins. Behind these is a pair 

 of maxillce divided into three 

 lobes, the outer and longer of 

 which is the feeler, or palpus. 

 Next in order is the lower lip, or 

 labium, apparently composed of 

 two lateral halves, each bearing 

 a palpus. 



'JLS n 



n 



, r ~. r Most biting insects 



FIG. 8. Mouth parts of a locust. . 



, antenna; I, labrum turned for- present mouth parts similar to 



these. The mosquitoes and 



\vard to expose the mandibles, m; 



n, maxilla reflected ; 6, palpi of 



the maxilla ; t, labium. Twice some flies and bugS have 



natural size. Drawing by Reese. . . . . 



ing but not biting mouth parts. 



The locust's body is divided into three parts: the head, 

 bearing a pair of many-jointed antennae; the thorax, sup- 

 porting three pairs of legs and two pairs of wings, the an- 

 terior of which are parch men tlike and serve to cover the 

 posterior which are membranous and folded longitudinally 



