ARTHROPODA. 295 



structive. The Rocky Mountain locust, so named because it breeds on the 

 plateau at the eastern base of these mountains, in 1873 and again in 1878, 

 migrated eastward over Nebraska and Kansas in search of food, literally 

 stripping fields of vegetation. Since the settlement of the regions where 



FIG. 137. 



FIG. 137. Katydid (Cyrtophyllus perspicillatus), natural size. Photo by Folsom. 



Questions on the figure. How many pairs of appendages are visible 

 in the figure? How many pairs are present? To what order of insects 

 does the Katydid belong? What are its feeding habits? What can you 

 find of its development? 



FIG. 138. 



FIG. 138. Periodical Cicada. Natural size. Photo by Folsom. 



Questions on the figure. To which order of insects does Cicada 

 belong? Which of its habits are most familiar to you? What are its 

 nearest relatives among the insects? 



they breed, with the ploughing up of the eggs and the destruction of the 

 young, there is reason to hope that these migrations are at an end. Ac- 

 counts of similar migrations of locusts are recorded in the history of the 

 old world. These migrations and their effects illustrate how climatic 



