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NOHlTH DAKOIPA 
This is the sixth year in which collections of grasshop{)ers have 
been made in the major habitats of the State, and 18,313 specimens Were 
. collected in 8 different habitats, about 65 species being, fepi^esented* 
Both small-grain and native grasses were classified as to western and 
eastern, v/ith the division line north and south through Bismarck, Melhn- 
oplus mexicanus was the dominant species in 7 out of the 8 environments 
■ and formed 37 percent of the total number of specimens collected. In the 
native grasslands, both eastern and western, Ageneotettix deorum was the 
dominant species. Compared with 1938, the 1939 collections showed a de- 
crease in the relative abundance of M, mexicanus in all environments ex- 
cepting small grain. Of the total niimber collected in the State, M, mexi- 
canus decreased from 49 percent in 1938 to 37 percent in 1939, ^or the 
range land, M , mexicanus was the dominant species in 1938 at 32 percent 
of the total specimens collected, whereas in 1939 it was second in numbers 
in the eastern section, at 18 percent, and fourth in the western part, at 
8 percent. This is a most decided decrease in general occurrence, M, 
bivittatus showed an increase in relative numbers, None of these data 
dispute the fact that there are extraordinarily severe infestations of 
M, mexicanus in eastern North Dakota, By far the greater number of the 
severe infestations lie in the northeastern part of the State, the 
severity of which has already been discussed in the first part of this 
report. The heavy infestation in this part of the State is due to two 
causes — first, a local build-up of infestations which were not adequately 
poisoned during 1939, and second, during July and August there was a 
gradual but steady influx of migrating adult's from the south as far as 
the northeastern part of South Dakota, 
a 
