120 OUTLINES OF ENTOMOLOGY. 



ity, number and duration." Another method of "fiddling" character- 

 istic of other species takes place during flight, when the under surface 

 of the upper wings is grated back and forth over the front edge of the 

 under wings. 



These insects are probably all single-brooded, the young hatching 

 in the spring from the eggs laid the previous summer and autumn. The 

 very young locusts have much larger heads in proportion to their bodies 

 than the more mature forms. There are five molts before the insect 

 arrives at its perfect form. At the third molt the embryo wings begin 

 to appear. These are in a reversed position with the under wings on 

 top. By this peculiarity pupse can always be distinguished from the 

 few species of locusts that never acquire wings, but have these organs 

 represented merely by short pads on each side of the abdomen. Ex- 

 amples of these wingless species are found in the Lubber Grasshop- 

 pers of the South and West, which are large, dark, clumsy species, 

 incapable of flight or stridulation. 



Our largest and handsomest species is the American Locust (Acri- 

 dium americanum), which is often more than two inches in length, with 

 a golden brown stripe down the back and beautifully mottled wings ; 

 the hind shanks are bright red, beset with spines, which are ivory-white 

 tipped with black. There are red markings also on the head, thora?: 

 and edges of the wings, and the fore and middle legs are also a paler 

 shade of the same color. The most common and generally distributed 

 species is the Eed-legged Locust fCaloptenus femur -rubrum DeG.). This 

 is scarcely more than one-third the size of the first-named species, is of 

 a pale, greenish-brown with dull-red hind legs. It often multiplies to 

 such an extent as to do great injury to growing grain. 



The Eocky Mountain Locust, or Western Migratory Locust fCalop- 

 tenus spretus, Thomas), is only to be distinguished from the familiar red- 

 legged species by the greater length of its wing-covers and wings. 

 Concerning the destructiveness of this species at irregular periods in 

 the States and territories west of the Mississippi river. Dr. Riley, who 

 has devoted much time and labor to the study of this insect, and to 

 devising methods for keeping it in check, writes : " It was so very 

 destructive in the Northwestern States and Territories from 1873 to 

 1877 that it may truly be said to have been one of the chief causes of 

 the business crises which characterized that period. So wide-spread and 

 disastrous were the results of its work that Congress provided for a com- 

 mission to investigate it. * * * No one who has not witnessed the 

 ravaging power of locusts can fully conceive of or appreciate it. The 

 organization and habit of the typical locust admirably fit it for raven- 

 ous work. Muscular, gregarious, with powerful jaws, and ample diges- 



