THE LOCUST OR SHORT-HORNED GRASSHOPPER 347 



and not a fused pair of appendages; the maxillce, which are 



clearly paired appendages; and the labium, which resembles a 



lower Up, although, unlike the labrum, it is composed of a pair of 



appendages sometimes called the second maxillae, which are fused 



together on the mid-Une. The three pairs of thoracic appendages, 



the legs, are similar in structure, although 



the most posterior pair is specialized for 



leaping. A minute pad and a pair of 



hooks at the end of the outer division 



function as grasping organs by means 



of which the animal secures a firmer 



hold during locomotion or when at rest 



upon the vegetation (Fig. 171). The 



abdomen of the locust is devoid of 



appendages and none appear in this 



region during development, although 



there are traces of such rudimentary 



appendages in the development of 



certain insects. 



The posterior end of the abdomen 

 differs in the two sexes, principally by 

 the presence in the female of the large 

 ovipositors (cf. Figs. 168 A and 180 A). 

 Between these is the opening of the 

 female reproductive ducts. In egg 

 laying the ovipositors are thrust into 

 the ground and then opened to form 

 the cavity in which an egg is deposited (Fig. 186). In the male 

 there is a thick, conical copulatoiy organ, or penis, which occupies 

 a position between the anus and the external genital opening on 

 the terminal segment of the abdomen (Fig. 180 B). 



There are two pairs of wings attached to the latero-dorsal sur- 

 faces of the mesothoracic and metathoracic somites, as is typically 

 the case in the majority of insects. The anterior pair is heavy 

 and membranous in some species of locusts, thus assuming the 

 nature of wing-covers rather than of wings. In the " lubber " 

 grasshoppers, both pairs of wings are greatly reduced with corre- 

 sponding reduction in the power of flight (cf. Fig. 168 A and B). 

 The wings of insects are composed principally of exoskeleton with 

 a very small amount of other material between the two layers. 



Fig. 171. — Locust resting 

 on stem of plant. 



(From Farmers' Bulletin No. 

 747, U. S. Dept. Agr.) 



