488 BULLETIN UNITED STATES GEOLOGICAL SURVEY. 



their rocliy bounds ; yet while these were vainly striving to leave their 

 mountain prison, another horde from the barren regions beyond, sweep- 

 ing above them over the snowy crest, poured down upon the valleys 

 east ; and in another instance a swarm was seen passing for two days 

 over Fort Hall from the southwest. On the other hand, we find them 

 extending their flight far into Texas in destructive hordes, yet New 

 Mexico and Arizona appear to be apparently free from them ; at least, the 

 xerj extensive collections made by Lieutenant Wheeler's expeditions in 

 these Territories during the last four years, which have been submitted 

 to me, contain but very few specimens of the G. spretuSj and during my 

 visit to New Mexico in 1869 I found scarcely any specimens south of 

 Eaton Mountains, -although comparatively abundant in Colorado, and 

 even in the San Luis Valley. I am, therefore, inclined to doubt the cor- 

 rectness of the statement made by Mr. Taylor (in Smithsonian Eeport, 

 1858) in reference to th.e grasshoppers in these Territories in 1855, if in- 

 tended to apply to this species. 



These facts, if added to the experience in Kansas, Nebraska, Dakota, 

 Minnesota, and Manitoba, will suffice to show, not only how extensive 

 is their range, but also how varied their flight, and that there are no 

 particular spots which can be said to form their i^ermanent hatching- 

 grounds. That they prefer the elevated sandy plateaus and terraces in 

 the mountain districts is certain ; but that any particular localities form 

 the permanent hives from which the swarms issue cannot be maintained ; 

 yet that those which visit Kansas and Nebraska, and even Dakota and 

 Minnesota, originate usually in the Upper Missouri region and adjacent 

 parts of British America is now pretty well ascertained. We may there- 

 fore set it down as impracticable to attempt their extermination by 

 destroying their eggs and young in the various hatching-grounds scat- 

 tered throughout this extensive range. It may be possible by preserv- 

 ing the grass in the last-named section, and burning it at the proper 

 time, to destroy the unfledged young. 



While there are exceptions to the rule, yet it is evident that their 

 general course of flight east of the mountains and south of the bound- 

 ary line is southeast. I have no positive information on this point in 

 reference to the region along and north of the boundary line, and there, 

 fore hope Dr. Ooues will add an account of such facts in this respect as 

 came under his personal observation or such reliable information as he 

 may have ascertained. The distance traveled by any particular swarm, 

 as is evident from what has heretofore been said, has never been posi- 

 tively ascertained, yet enough is known to indicate that this may extend 

 for at least two and possibly three hundred miles. 



The hordes which visited Colorado in 1864 are supposed by Colonel 

 Byers, from certain evidence then ascertained, to have originated in 

 Montana along the Yellowstone ; and a swarm which I traced through 

 Sweetwater Valley in 1870 probably moved over two hundred miles ; 

 :yet the evidence, though highly presumptive, is not positive in either case. 



