220 



The auiouut of land that can be brought under cultivation depends wholly upon 

 the amount of water that cau be obtained for irrigation. If the phin for making res- 

 ervoirs for preserving the winter supply should ever be adopted, the breadth of the 

 agricultural belt would be very largely increased, and this would be doubly benefi- 

 cial in assisting to destroy the locusts and tending to increase the moisture in the at- 

 mosphere by forming a larger evaporating surface. The growth of trees and shrub- 

 bery around these reservoirs would also be beneficial in the same direction. 



But experience in the settling of these mountain regions and Western Territories 

 shows that no such extensive works will, or in fact can be, undertaken by a pioneer 

 ao-ricultural population. Some efficient aid of some kind must be given if such a 

 scheme is ever carried into effect, and ff the land itself will do this, the Government 



will act wisely in giving it for this purpose. 



♦ #*#»#* 



As shown by our first report the region around Salt Lake is subject to repeated 

 locust Invasion from the north, apparently the resulting broods of the swarms that 

 originate in that portion of Montana of which we have been speaking, and which, 

 pouring over the mountain-pass at the head of Jefferson River, move down Snake River 

 Valley. 



If the scheme we have suggested should be carried out and should prove beneficial 

 in reference to the eastern area, it would have, to some extent at least, a like effect 

 as to this section. If it is possible to establish and maintain an agricultural popula- 

 tion in the Upper Snake River Valley, this would have a strong tendency to modify 

 the evil. But the present barren aspect of this region would seem to forbid any hopes- 

 of ever accomplishing this desired end. Still there appears to be one possible means 

 of bringing this about, at least to a limited extent. The demand of trade will doubt- 

 less complete the railroad already started in that direction, which is one step toward* 

 the desired end, but something more is required in this case. 



Snake River affords a large body of water which if properly utilized would irrigate 

 a large breadth of land, and notwithstanding the barren appearance of the soil, it ia 

 really fertile when irrigated. It is possible, with a moderate expense, to throw dams 

 across this stream at certain favorable spots, and by this means to spread the water 

 over the adjoining plains. A work of this kind would, of course, have to be done by 

 the General Government. The feasibility of this project could easily be ascertained 

 by an officer of the Engineer Corps of the Army ; and as this is on the line of the 

 chief inter-montane thoroughfare, and also of the locust invasions of this region, the 

 subject is certainly worthy of the attention of the Government. 



As will be seen by what we have presented on this subject, the philosophy of our 

 plan for modifying the evil is to place an agricultural population in the very home 

 of the species, which from necessity would be compelled to wage a constant warfare 

 against them. 



By stirring the soil their nests would be disturbed ; by fighting the young their 

 numbers would be diminished; and as irrigation would be necessarj', the effect of 

 dry seasons on the crops would not be felt as in the temporary region. The possi- 

 bility of inundating to a considerable extent their egg deposits by the winter supply 

 of water would tend to diminish their numbers. The fact that their breeding- 

 grounds are chiefly in the limited agricultural areas is also another argument in favor 

 of the plan. 



That large areas would be left where locusts breed and pour down on the nearest 

 cultivated areas, as in western Colorado, is certainly true, but this does not lessen 

 the value of the plan proposed, nor is it a reason why it should not be put into 

 operation. 



The effect of irrigation upon the Eocky Mountain Locust dwarfs into 

 comparative iusigniticauce auytbiug which may be said concerning its 

 influence on other destructive species, yet there are many forms which 

 depend for their existence and multiplication upon a dry climate, and 



