14 GENERAL ZOOLOGY 



abdomen are slowly withdrawn while soft, expanding and 

 hardening within half or three quarters of an hour (Fig. 6). 

 It is now a perfect insect, or imago, of full size and with fully 

 developed wings. After the females have laid their eggs in 

 the fall most of the locusts die. 



Relation to Environment. Red-legged locusts are found in 

 meadows, pastures, fields, and along roadsides, though most 

 abundant where the vegetation is succulent. Specimens from 

 low, damp ground are usually somewhat darker in color than 

 those from high, dry areas. Their food consists of the leaves 

 of grasses and other vegetation. The strength of the man- 

 dibles and the complexity of the digestive system fit them 

 admirably for a life of constant forage. Their color is, to a 

 certain extent, protective, for they are not easily seen among 

 the dried grasses of the summer. 



Locusts have, when adult, a choice of three methods of 

 progression, walking, jumping, and flying. The many spines 

 pointing downward on the legs and the pulvilli between the 

 tarsal claws make climbing an easy matter. The complicated 

 system of air-sacs tends to reduce the weight of the body in 

 flight. By means of the air-sacs and wings the locust has 

 solved the problem of aerial locomotion. 



The list of the locust's enemies is long and formidable, 

 even if man is not considered. Small animals, such as moles 

 and birds, especially the crow and blackbird, feed on the 

 eggs and young. Some species of wasps use the nymphs to 

 provision their nests, first stinging them to render them help- 

 less. They are also subject to a disease caused by a fungous 

 growth, and may often be found firmly attached to some grass- 

 blade to which they have clung before death. That they have 

 been able to maintain themselves in such large numbers in 

 spite of all their enemies marks them as successful competitors 

 in the struggle for existence. 



