640 REPORT UNITED STATES GEOLOGICAL SURVEY. 



think that it is not yet mucli to be dreaded in Calit'oruia. We have uo 

 other species that I am avrare of in large numbers. Spretus has beeu 

 taken by me near Portland and at the Dalles, Oregon, and still more 

 abundantly at Victoria, Vancouver's Island, but I have never seen it in 

 the Sierras; my idea being that it is always (here at least) confined to 

 the valleys and plains, lu proof of this, the locality in Marin County 



to which I have alluded is at the base of Mount , and on the sides 



of the mountain itself the grasshoppers were not found at all. I do not 

 think it goes far south of San Francisco. I have seen one or two from 

 Santa Barbara, but none from below that point. Perhaps it may be re- 

 placed by another species. We have no literature that I know of on 

 the subject, save a few newspaper notices, which I will try to find and 

 send to you. At jiresent, we are strangely exempt from all destructive 

 insects." 



California in former years has had its locust invasions, although we 

 are entirely uncertain as to the species forming the swarms. In differ- 

 ent parts of California they hav<j appeared in the following years, ac- 

 cording to Mr. A. S. Taylor (Smithsonian Report for 1S58): 1722, 1746- 

 1749, 1753 and 1754, 1705-1767. In the present century they have been 

 abundayt and destructive about 1S27 or 1828, about 1834 or 1835, and 

 in 1838, 1846, and especially in 1855. 



THE GEOGRAPHICAL DISTRIBUTION OF THE ROCKY MOUNTAIN LOCUST. 



A glance at the accompanying map, showing the distribution of the 

 Rocky Mountain locust {Calopienus sjrretus), will show the probable limits 

 within which it will be found. At least there is no probability that 

 the locust will ever afflict farmers east of the limits assigned. 



The eastern limits have been defined by Professor Eiley for Texas, Indian 

 Territory, Missouri, Kansas, ^STebraska, and Minnesota, while the north- 

 ern and northeastern limits have beeu indicated by Prof. G. M. Dawson. 

 The southestern limits are somewhat conjectural, but have been indi- 

 cated to me by Maj. J. W. Powell. The western limits in Nevada 

 and Idaho have been pointed out to me by Prof. Cyrus Thomas. 



The range of the small variety («^/ams .^) in California and British 

 America (Vancouver Island) has been indicated by Messrs. H. Edwards, 

 S. H. Scudder, and myself; while the eastern range of the eastern 

 variety atlanis has been indicated by Messrs. Riley, Thomas, Scudder, 

 and myself. 



The locust area is divided into two regions, one the permanent 

 breeding-places, on the elevated plains among the Rocky Mountains 

 and the great plateau lying east and extending approximately to longi- 

 tude 102°. Beyond the edge of the great plains are found the tem- 

 porary breeding-places of the locust, which comprise the prairie-lands 

 of the border States as far east as longitude 93° or 94^. The arrows 

 with simple shafts indicate the course of the migrations from the origi- 

 nal, usually permanent, breeding places, and the arrows with a feathered 

 shaft the return migrations from the temporary breeding-places periodi- 

 cally visited. 



THE MIGRATIONS OF THE ROCKY MOUNTAIN LOCUST OF THE WEST. 



In dealing with this fearfully-destructive insect, whiph has attracted 

 so much notice from the public, and in seeking for remedies against its 

 devastations, it is of prime importance to have a thorough knowledge of 

 its breeding- places, the frequency and extent of its migrations, and to 

 seek for the connection between the direction of the winds and other 

 meteorological phenomena and the flights of the locust. 



