320 REPORT UNITED STATES ENTOMOLOGICAL COMMISSION. 
regions of the Rocky Mountains which will ultimately be taken up by 
settlers as fanning and grazing lands; hence, when this region is settled, 
the prevention of locust injuries will be a problem much easier of solu- 
tion than at present. 
"The effect of putting this large area under more or less thorough 
cultivation, either as irrigated farms or cattle and .sheep ranges, will be 
to render the country less liable to great and prolonged drought, and 
thus cause the climate to be more equable. All this will tend ultimately 
to keep the locust within its normal limits, so that it will not in certain 
favorable years multiply to so great an extent as to lead to extensive 
migrations into adjoining or remote regions. The locusts will be re- 
strained within their natural and original limits. Hence the best means 
of protection will be to destroy the eggs and to li«,dit the young when 
they hatch, and to exterminate them by all the methods fully described 
in the First IJeport of the Commission. The greater the number of eggs 
and young destroyed within the Permanent Region year after year, over 
a period of 25 or 50 years, the more will the number of individuals 
throughout the whole area be lessened. 
"The settlement of Montana and the western border of Dakota will 
ultimately have a great effect in lessening the extent of the breeding 
grounds of the locust ; and thus diminish the numbers of those which 
swarm into Utah on the one hand, and Minnesota, Iowa, and Nebraska 
on the other. 
"The State of Colorado is invaded by swarms w hich originate west ol 
the range about the White and Bear Rivers, and north and northwest 
from the Wind River Valley aud the Laramie plains of Wyoming, so 
that these regions are the tracts which need to be occupied, aud where 
an unremitting warfare, pursued with combined effort year after year 
by the farmers, will ultimately tend to keep the locust within compara- 
tively harmless bounds. 
"To this end the replanting of the forests, now being recklessly cut down 
by the settlers of the Western Territories, w ill have a favorable effect, 
both tending to reduce the extremes in the seasons, and to break up and 
diminish the breeding grounds of the locust. Moreover, the construction 
of railroads and the settlements which spring up along them will have 
their effect in reducing the extent of the breeding grounds. 
" The settlement also of the wild lauds of the Rocky Mountain plateau 
will in a measure tend to keep the locusts from migrating eastward. 
If there were a sufficiency of food in the plateau region, there would be 
no inducement for them to take flight for regions situated five hundred 
to a thousand miles eastward, for without much doubt the main cause 
of their migration is the desire for food ; for if the broad, extended plains 
of the region between the mountains and the Mississippi Basin do not 
afford them sufficient food, they will pass on to the prairie region of the 
western edge of the Mississippi Basin. 
" While, therefore, we do not see how any special means of extermi- 
