PKEFACE. 
XV 
distribution, left incomplete in our former map. He obtained import- 
ant data upon the habits of the locust in that section and found that 
they had flown in and about Santa Fe from the north during the years 
1865, 1868, 1874, and 1877, and he also traced them into Eastern Arizona. 
Mr. Thomas during this year devoted his time more particularly to the 
meteorological facts bearing upon the increase and development of the 
locust. He was forced to the conclusion that the meteorological data 
hardly bore out the generally received opinion that heat and dryness are 
necessary to excessive increase, but that winter conditions have greater 
influence than has been suspected. While the data he obtained have 
comparatively little value, therefore, "and the annual and monthly means 
were of no value whatever as throwing light on increase and develop- 
ment, the daily records proved most valuable in their bearing on flights. 
In planning this report it was decided to introduce with the more 
practical chapters a few giving the results of some of the purely scien- 
tific work that has grown out of the inquiry. 
In Chapter I, Messrs. Packard and Eiley have added to the hitherto 
published chronological history of locust injury by giving data for the 
past and the present year. 
In Chapter II, prepared by Mr. Thomas, the subject of the relation 
of the locust and its ravages to agriculture and the settlement of the 
Territories is discussed in all its different bearings. Different plans of 
inducing increase in the purely agricultural rather than the pastoral 
population, the difficulties in the way of successfully burning over the 
locust-infested area, and the non -feasibility of other plans are dwelt 
upon; and while utter extermination of the pest is out of the question, 
it is clearly shown that the evil may be materially modified, and that 
government action in the matter is warranted because the evil is essen- 
tially a national one. 
In Chapter III, also by Mr. Thomas, a mass of information is brought 
together in regard to the laws governing the migrations of locusts in 
all countries. It is there shown that the essentially migrating habit is 
confined to about four species, all of them inhabiting and coming from 
treeless, arid, and elevated regions. In a few instances a species which 
is sedentary in one part of a continent becomes migratory in another. 
As in the case of our own species, there are no laws of periodicity gov- 
erning destructive flights, these only occurring at irregular intervals. 
Nevertheless the history of the most noted locust years, both in this 
country and in Europe, shows a tendency to their recurrence about every 
eleven years. It is also shown that the European and Asiatic species 
have, hke our own, areas where they permanently breed, and from which 
they swarm in exceptional years to extend over adjacent regions in 
which they are not found permanently. 
Chapter IV, also by Mr. Thomas, treats of the habits and characters 
of locusts in different countries within their areas of permanent distri- 
bution, especially so far as such areas relate to their movements. The 
