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IOWA 
This is the fourth 7 ear in which collections were made in 
Iowa, in the adult survey. Collections have been made in 1935, 1936, 
1937, and 1933* In 1936 the specimens were boxed up ready for shipment 
and allowed to lie around the insectary, and mice destroyed the lot. 
This is written in as a warning that mice will do this to dried grass- 
hopper specimens, and proper care must be taken to prevent it. It has 
happened at the Bozeman, Mont., laboratory and means simply a wasted 
effort on the part of the collector and lost information on the part of 
the grasshopper survey. 
There were 11,853 specimens collected in 8 major environments and 
29 species were represented. Undetermined nymphs made up 40 percent of 
the total collection and most of these were probably Mel ano plus femur - 
rub rum . The dominant species in the collections was M . f emur - rub rum , not 
including nymphs. M. mexicanus and H. differentialis were second in numbers. 
In the legumes and pastures H. f emur-rubrum was most numerous, whereas in 
corn M. differentialis was by far the most important grasshopper. It 
must be understood, however, that these collections are made rather late 
in the season, and some portion of the early maturing species, like II, 
mexicanus and M. bivittatus , may have finished their life cycle and gone, 
M, femur- rubrum is a very late-maturing species and adults of these hardly 
show up before July 15, but would be numerous in collections made in 
August, There has been some great change in the relative numbers of speci- 
mens collected in 1937 and 1938, M, f emur - rubrum was not of such great 
importance in 1938 a.s in 1937, M. difforentiali s > on the other hand, has 
increased its relative percentage of total number specimens collected 
from 5 percent in 1937 to 13 percent in 1938, and in corn from 31 to 52 
percent,- It has approximately doubled its relative importance in all 
environments. 
Hatching of M. mexicanus and M, bivittatus began the last week of 
April, with heavy rains prolonging the hatch all through May and part of 
June, II, differentialis did not begin hatching until about the first of 
June, Continued rains held infestations in check and reduced the nymphal 
populations from 50 to 80 percent of their possible numbers. In fact the 
grasshopper potential for the entire State was reduced to one-half of what 
it was in the 1937 survey. There were some second-generation of M. mexicanus 
but not as ma,ny as in 1937. The outlook for next year is about half as 
serious, with the greatest losses to be expected from M. differentialis . 
