126 REPORT UNITED STATES ENTOMOLOGICAL COMMISSION. 



apprehended from the youDg insects, and so far as possible to allay the 

 fear and apprehension of invading swarms. And they feel warranted 

 in saying that in this respect their efforts were crowned with more 

 favorable results than could have been expected. 



The relation of the locust problem to the condition of the country as 

 to humidity or aridity is so intimate that it cannot be thoroughly under- 

 stood without a knowledge of the latter, nor is it likely that a complete 

 solution will ever be found so long as the arid condition of a large por- 

 tion of the West remains as it is. 



The migratory habit of locusts, whether in the Eastern or Western 

 Continent, is now known to be directly or indirectly attributable to the 

 arid condition of the area in which they originate. It is only in broad 

 and extensive and comparatively barren regions that we find them per- 

 petuating their race and maintaining their migratory habits. Such 

 areas form the great hives in which they multiply and from which they 

 pour forth the vast hordes that fall upon the more fertile surrounding 

 districts. This fact has been known and understood for ages past ; and 

 numerous facts, gathered in recent years, show that where man by his 

 folly has converted fertile districts into barren areas, these, likewise, 

 become the home and prolific hives of the migratory locust. 



As is shown elsewhere, the eastern limit of the movements of our 

 migratory species is along the eastern line of Minnesota, middle line of 

 Iowa, and western border of Missouri j but if from any cause these 

 States should ever become as arid as the i^lains lying west of them, then 

 the locust-swarms will be seen moving eastward across the Mississippi 

 in search of more fertile fields. It is evident, therefore, that the final 

 and complete solution of the locust problem depends to a certain extent 

 upon the possibility of modifying, to some degree at least, the aridity of 

 the great plains of the Northwest, which undoubtedly form the native 

 breeding- grounds of these insects. 



By most persons this will be considered equivalent to saying that the 

 locust problem will never be solved. It would scarcely be proper for us 

 here to enter into a discussion of the question of the possibility of modi- 

 fying the condition of the dry area, but we cannot refrain from placing 

 upon record our protest against any such conclusion as this. That man, 

 with a mind that can bring art, science, and mechanics to the perfection 

 now visible on every hand, must be forever unable to convert the des- 

 ert into fertile fields, or to redeem the waste places of earth, w^e cannot 

 believe, unless we are shown that the moisture which once supplied these 

 areas has forever taken its departure from our globe. 



To what extent these dry areas of the West can be supplied with water 

 and rendered fertile must be determined by those who are proficient in 

 -this particular branch of science ; but, that large sections can be re- 

 deemed by proper efforts, if made on a scale of sufficient magnitude, we 

 have no doubt. 



By utilizing all the water that flows down from the mountains for the 



