FORAGE LOSSES CAUSED BY RANGELAND GRASSHOPPERS 9 
ESTIMATES OF FORAGE LOSSES 
Estimates of the amount of forage loss due to 
grasshoppers have been reported in dollars, in 
acres infested, in cost of control, in percentage of 
vegetation destroyed, and as forage consumption 
compared to livestock. Most estimates of monetary 
forage losses are given for the 1930’s because nu- 
merous grasshopper outbreaks occurred during 
those years. 
Morton (1939) estimated from Forest Service fig- 
ures that during 1934 grasshopper damage to 
rangeland in Colorado, Montana, Nebraska, North 
Dakota, South Dakota, and Wyoming amounted to 
$2,455,000. This figure represented only the value 
of the forage destroyed and did not include indirect 
losses by importation of feed, removal of livestock, 
forced sale of livestock on low markets, liquidation 
of foundation stock, and increased erosion due to 
reduced vegetation cover. He also estimated that 
during 1935 and 1936 losses were probably just as 
great. 
Pfadt (1949b) reported that C. L. Corkins, State 
entomologist of Wyoming, aided by the county 
agents estimated that the loss in Wyoming in 1936 
due to range grasshoppers amounted to $1,480,000. 
Hinkle (1938) reported that one species of grasshop- 
per, Dissosteira longipennis (Thomas), caused 
$1,500,000 damage to crops and forage in Colorado 
in 1937. A summary of losses from 1925 to 1934 was 
reported for Canada by Buckell (1936) and for the 
United States by Parker (1937). Knowlton (1952) 
estimated damage in Utah at $200,000 per year 
since about 1934 after organized control programs 
were established. Parker and Connin (1964) stated 
that the average yearly loss to range and pasture 
grasses is estimated to be about $80 million in 17 
Western States. 
Figures given for controlling grasshoppers or 
hectares infested usually included mixtures of both 
cropland and rangeland. For example, Knowlton 
(1966) reported that 194,800 ha of range and crop- 
land were infested in Utah in 1966. Parker (1933) 
reported a grasshopper outbreak in South Dakota, 
North Dakota, Nebraska, and Iowa in 1931 which 
included 43,518 km? of which 19,199 km? were in 
crops. McDonald (1965) reported that in 1962 about 
23,200,000 hectares of land were infested in Mani- 
toba, Saskatchewan, and Alberta. Following con- 
trol by baits and insecticides, a number of workers 
reported on the value of such control campaigns. 
Parker (1933) reported on a 10-year period, 
1913-23, in which eight States and three Provinces 
were treated. A total of $3,265,189 was spent on 
grasshopper control with an estimated savings of 
$141,692,975. He also reported the largest expendi- 
tures recorded as being $604,571 for North Dakota 
in 1919 and $540,000 for Alberta in 1922. Paul 
(1940) estimated crop damage (probably wheat) 
from Saskatchewan in 1934 based on farm records. 
He said crops valued at $605.61 per farm were 
saved as a direct result of grasshopper control. The 
average crop loss was 24 percent, whereas without 
control the damage would have been almost three 
times as great, 66 percent. An average gross sav- 
ings of $5.23/ha was obtained from a total bait cost 
of $0.16/ha. 
Munro (1949) stated that the total cost of grass- 
hopper control was $27,337,808 in 24 States during 
1936-47. He conservatively estimated that these 
expenditures resulted in savings of $693,323,388 
worth of crops during the 12-year period. Mce- 
Donald (1965), using the calculations of W. B. Fox, 
estimated the value of the crop saved per dollar 
expended for grasshopper control in Alberta to 
range from $100 to $200 for 1949-53. Harper (1952) 
gave the figures for the 1952 season in California as 
116,000 ha treated at an approximate expense of 
$610,000 and a crop savings of $13 million. 
A number of workers have also estimated the 
amount of forage consumed by different grasshop- 
per densities but have failed to consider the food 
preferences of the various rangeland species. 
Drake and Decker (1932) stated that as a grasshop- 
per generally eats about one-tenth of its weight at a 
meal and as it frequently feeds several times a day, 
an individual may consume about one-half its 
weight of green food every 24 hours. They also re- 
ported that when grasshoppers in a field average 
about 20.4 per square meter they will consume ap- 
proximately 900 kg of alfalfa hay per day. 
Cowan (1958) estimated that grasshoppers an- 
nually consume from 6 to 12 percent of the available 
forage in the Western States. This amounts to be- 
tween 4,205,700 and 8,984,700 metric tons (t), 
which would support from 2,492,000 to 5,324,000 
additional animal units. Forage utilization by grass- 
