CHARACTER OF CHAPIERS. 25 



progress and development of the West j the crops most liable to and 

 those most exempt from injury. It also discusses the best modes of 

 cropping and the modeof farming that will give greatest security against 

 locust ravages. 



The facts brought forward in considering the native or permanent 

 breeding-grounds (Chapter 5) show this locust to be essentially boreal, 

 and that, in its normal condition, it is confined to the more northern 

 plains. The area of its permanent abode lies principally east of the 

 mountains, between latitude 37° and 52^ and reaching to about the 

 102d meridian. West of the range the permanent breeding-grounds 

 seem to be confined to more limited areas in the Snake River Valley and 

 Cache and Malade Valley regions. 



The chapter (6) on geographical distribution gives the limit of the 

 range or spread of the species. The data obtained during the year fix 

 the eastern limit along almost precisely the same line at which it had 

 been previously established, broadly along the 94th meridian j but the 

 northern, western, and southern boundaries are for the first time estab- 

 lished with anything like definiteness. The exact eastern limit is given in 

 the chapter. It is an interesting fact that both north and east the limit 

 is, in the main, coequal with the timber line. West of the mountains 

 the line is in the neighborhood of the 118th meridian, the Cascade and 

 Blue Mountain Ranges and the moisture beyond them appearing to be 

 the most obvious barriers. 



The Commission has made an especial effort to record all the move- 

 ments of locusts during the year 1877, no less than 2,500 observations 

 being recorded. The managers of each of the three lines across the 

 country, viz, the Atchison, Topeka and banta Fe, the Kansas Pacific, 

 and the Union Pacific, assisted us by republishing our queries and in- 

 structing their agents to report, so that we had three almost parallel 

 lines checking each other. 



The data in the chapter (7) on migrations and in the appendix 

 (Ajjp. 12) show very clearly that the movements of the winged insects 

 that hatch out in the temporary region is toward the north or the north- 

 west early in summer, the direction being more and more due north 

 toward the eastern limit. In other words, there is, as we first declared 

 three years ago, a return migration toward the native breeding-grounds 

 of the insects hatching in the temporary region. This return move- 

 ment is very constant east of the i)lains and south of the '44:th parallel, 

 but less so north and west of those lines. Thus in Minnesota, from 

 which the reports are very complete, the movements are much more 

 irregular than in Iowa, and they are most regular in Texas. It is well 

 established that there may be two contrary currents over considerable 

 areas, while good evidence is produced to show that flight is not unfre- 

 quently continued into the nighr, especially during fair, warm, and dry 

 midsummer weather. 



The observations in the extreme Northwest are meager, and while 



