217 



fare of a much larger area south and west also depends upon it, certainly the ques- 

 tion is worthy of consideration by our national authorities. 



The day is not far distant when our National Government will be compelled to meet 

 this important question and to test the ability of man to accomplish the work. 



The progress of settlement westward must necessarily be slow when it, as is uow 

 beginning to be the case, impinges upon the sterile area; it can only push onward 

 when the front line Is backed by a dense population and fjirms studded with groves. 

 It is possible that if there were no other impediments to overcome than this sterility, 

 formiaable as it is, the gradual tilling up of the border area with an active population 

 would modify the conditions sufficiently, at least, to allow the pushing into and re- 

 demption of a belt of considerable breadth. But when to this difficulty is added the 

 devouring locust the hope of success is greatly diminished. * * • 



In the permanent region, which embraces the Rocky Mountain plateau and the 

 bordering plains from the middle of Colorado northward, the rain-fall is insufficient 

 for agricultural purposes, and hence irrigation has to be resorted to ; in the tempo- 

 rary region this is unnecessary. The plains and plateaus of the permanent region are 

 to a large extent distinguished by the presence of Artemisia, Chenopodiaceous plants, 

 and what is usually termed "bunch-grass;" in short by all the characteristics of a 

 drier climate. One other peculiarity which has not been overlooked appears to 

 mark roughly the southern boundary of the permanent home of the Rocky Mountain 

 locust, and that is the isothermal curve or line of the 50^ of mean annual tempera- 

 ture, which also corresponds very nearly with the isothermal curve or line of sum- 

 mer temperature of 70". But this applies only to .that portion of the region which 

 extends upon the plains east of the mountains. 



If any practical means of exterminating the locusts in this permanent region could 

 be devised the whole locust problem could be solved, and nothing further would be 

 necessary; but when we take into consideration the vast extent of this area, and the 

 fact that a very large portion of it can not be brought under cultivation without 

 a material change in the climatic conditions, there appears but little hope that such 

 a means of actual extermination will ever be devised, however much we may hope to 

 check the injurious increase of the pest by the means recommended in the conclud- 

 ing chapter of this report. Our discussion of the future prospects of this region in 

 reference to agriculture may as well, therefore, be on this basis. 



* * * A careful investigation of this subject for several years and repeated visits 

 in person to this region have served to convince us that, with the advantages afforded 

 the system of irrigation necessarily adopted, there is no reason why the agricultural 

 area lying along the east flank of the range should suffer any more from these pests 

 than portions of the temporary regions. 



This agricultural belt, extending from Colorado into British Americ^., is partly 

 along the margin of and partly in the very heart of the permanent breeding grounds 

 where the swarms that invade the temporary region originate. It follows, then, as 

 a natural consequence, that just so far as the numbers are lessened by the operations 

 in this section, just so far will the agriculturists of the temporary region be benefited, 

 and, as we will hereafter see, like operations in the latter region will benefit those in 

 the permanent region. We are fully avrare of the fact that the part of this vast re- 

 gion which can be irrigated and cultivated is small in comparison with the whole 

 area which forms the native home of the species ; but, fortunately, in one respect this 

 cultivated belt occupies, in part at least, the point of departure of the swarms which 

 invade the temporary region. This fact, therefore, renders it more important that it 

 be occupied by an agricultural population. 



Although we have admitted that we are unable to present any plau of exterminat- 

 ing the locusts that holds out sufficient promise of success to justify the General 

 Government in undertaking it, it does not necessarily follow that there is no plan of 

 modifying the evil which the Government would be justified in undertaking. On 



