Review of Forage Losses Caused by 
Rangeland Grasshoppers 
By GeorGE B. HEwITT, research entomologist ' 
INTRODUCTION 
Grasshoppers have been of economic concern on 
rangeland in the United States since 1877 when 
the Rocky Mountain locust, Melanoplus spretus 
(Walsh), damaged both crops and rangeland vege- 
tation to the extent that the U.S. Entomological 
Commission was created by Congress to investigate 
the problem (Riley 1892).? Crop protection was the 
main concern of the early settlers, and only in more 
recent years have rangeland losses been of concern. 
Parker (1933) stated: 
The control of grasshoppers on rangeland is a problem that 
is demanding attention. Forestry officials have complained 
that the grazing capacity of the national forests is being re- 
duced by grasshoppers, and cattlemen in Texas have asked 
for help in protecting the extensive areas of rangeland in 
that state from the ravages of grasshoppers. In British Co- 
lumbia grasshopper control on rangeland is more important 
than in cultivated crops. 
Even as late as 1948, public interest generally 
was not focused on control of grasshoppers on 
rangeland (Wakeland 1951). However, grasshop- 
pers have continued to be the most conspicuous 
and damaging insects on western rangeland. 
According to Cowan (1958), damage to rangeland 
varies geographically and from year to year. It is 
governed largely by the grasshopper species com- 
plex, the vegetation complex, the numbers of 
grasshoppers, and the weather. Three types of 
damage are possible: (1) Removal of forage in direct 
competition with livestock, (2) permanent damage 
to the plants due to continued feeding by grasshop- 
pers beyond accepted percent use factors, and (3) 
‘ Rangeland Insect Laboratory, Agricultural Research Serv- 
ice, Montana State University, Bozeman, Mont. 
? The year in italic, when it follows the author's name, refers 
to Selected References, p. 16. 
destruction of seed heads, which prevents natural 
reseeding. 
Newton and Esselbaugh (1952) stated that when 
grasshoppers feed on the top of plants they are con- 
suming forage or browse in direct competition with 
livestock, and when they feed on plant material 
near the ground they are contributing to overgraz- 
ing and weakening the root reserves in the stand, 
and may possibly be making way for later soil 
erosion. 
According to Parker (1937), undetermined costs 
associated with grasshoppers fall into two cate- 
gories: (1) Losses of livestock, which includes ani- 
mals that died as a result of the destruction of pas- 
tures by grasshoppers, animals that were marketed 
prematurely or moved to new pastures with addi- 
tional expenses incurred as a result of grasshopper 
damage, and losses due to decreased output of live- 
stock products due to grasshoppers and (2) indirect 
losses, which includes families receiving relief in 
grasshopper and drought areas and losses in reve- 
nue due to crop losses and land abandonment. 
Spackman et al. (1966) reported on how to figure 
the cost of not controlling grasshoppers. If pasture 
is available, one may estimate the cost at going pas- 
ture rent prices. If pasture is not available, one may 
have to calculate the cost of hay plus the cost of 
feeding it. If additional pasture cannot be rented 
and hay is not available or the price of either rises 
to prohibitive levels, herd reduction may be the 
only answer. The effect of this drastic measure 
lasts longer than the source of the problem. This 
also results in area unemployment, which is multi- 
plied in local businesses. The decision whether or 
not to control grasshoppers is often difficult to 
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