82 



ELEMENTARY ENTOMOLOGY 



in color, but the hind-wings are black, with a broad yellow edge 

 quite conspicuous in flight. Throughout the Mississippi Valley 



the differential locust 

 (Melanoplus differ- 

 entialis) is one of 

 the most destructive 

 forms, being particu- 

 larly injurious after 

 floods, when it multi- 

 plies rapidly on the un- 

 cultivated land which 

 has been flooded. A 

 generation ago (1874 

 -1877), the crops of 

 the western part of 

 the Mississippi Val- 

 ley were utterly de- 

 stroyed for several 

 Mountain or migratory locusts 



FIG. 101. Rocky Mountain locust laying eggs 



a, females ovipositing, with earth cut away to show tip of 



abdomen placing eggs at d, and completed egg mass at e ; 



f, eggs. (After Riley) 



years by the clouds of Rocky 

 (Melanoplus spretus)vi\\\Q\\ 

 swooped down from the 

 tablelands of the northwest, 

 where they bred and mul- 

 tiplied. Accounts of the 

 numbers and voracity of 

 these locusts seem almost 

 incredible to-day, except to 

 those who have seen an 

 occasional outbreak in the 

 northwest, for with the set- 

 tling and development of 

 the western plateau they 

 have become less abundant, 

 and the species is now 

 injurious only very rarely 

 in Manitoba. In the mid- 

 dle and southern states the 

 large bird grasshopper, or 



FIG. 102. The Carolina locust (Dissosteira 

 Carolina}^ female. (Slightly enlarged) 



(After Lugger) 



