- 217 - 
A study of the collections made in the different natural vegetation 
areas indicates that the greatest number of species occurred in the short- 
grass or plains-grassland region. Michigan and Wisconsin lie in. the hardwood 
and pine-timber region, with rank vegetation. The collections from these 
States represented only 12 species. In the collections from Iowa, Minnesota, 
and other tall-grass prairie areas the number of species was 22. The collec- 
tions from the western parts of the Dakotas, Nebraska, eastern Montana, 
Wyoming, and Colorado averaged about 44 species. At elevations of from 
4;000 to 5,000 feet in Colorado or foothill region the number was 40; in the 
lower montane zone, from 6,000 to 7,500 feet, there were 32 species; from 
8,000 to 8,500 feet there were 14; and above 10,500 feet there were only 5 
species. These figures have only a relative significance and do not represent 
the actual number of species occurring in the natural vegetation areas. 
Utah in the northern desert-shrub region yielded 24 species. 
When collections were made in a crop, special effort was made to sweep 
only in that crop. Field-margin collections were divided between soddy and 
weedy types. Pastures were fenced, and consisted of native or introduced 
grasses of relative small acrea.ges surrounded by cultivated crops. The 
native grasslands were large tracts not affected by cultivation. For each 
State the total number of each species is shown as a percentage of the totrl 
number of specimens- collected in the State during the survey. The relative 
distribution of species is listed for the States and the five most important 
species in each environment are also given. 
It must be understood that the collecting was very general in character 
ond not all the species are represented. In future work more attention will 
be paid to careful collecting in specific natural vegetation areas, as con- 
trasted with introduced conditions. This should give seme information relative 
to the effect of cultivation on grasshopper populations. When thousands of 
acres of lush grain appeared in the prairies of South Dakota, there came can 
enormous increase in population of Melanoplus differential! s Thos. and M. 
bivittatus Say, until in 1931 the hordes of these pests stripped bare an area 
of 30,000 square miles. Then, as increasingly dry years followed, climaxed 
by the great drought of 1934 and the subsequent destruction of crops and 
depletion of native vegetation, these two species all but vanished. In 1935 
along river courses, they are again staging a comeback in certain pla,ces. 
COLORADO 
The collections in Colorado were made in 11 different environments, as 
shown in the table of the distribution of species. These represent the general 
habitats found on the plains, in the foothills, on the mountains, and in high 
mountain -and alpine meadows. The elevations for these ranged from 3,500 to 
12,200 feet. The annual precipitation ranges from 10 to 25 inches, with the 
rainfall increasing in amount and frequency with the increase in elevation. 
These natural vegetation zones .are as follows: 
1. Plains — grama, buffalo grass association — 
Dry and somewhat xerophytic, with an annual precipitation of about 
10 inches. 
