FORAGE LOSSES CAUSED BY RANGELAND GRASSHOPPERS 13 
was removed by an average population of 9.25 
grasshoppers per square meter and 62 percent of a 
sparse stand was damaged by an average popula- 
tion of 4.19 grasshoppers per square meter. They 
concluded that heavy damage could result from a 
comparatively low population, and that little rela- 
tionship exists between the amount of damage and 
number of grasshoppers per square meter unless 
the species are known. Western wheatgrass was 
particularly susceptible to damage by four species: 
Drepanopterna femoratum, Metator pardalinus 
(Saussure), Aulocara elliotti, and Phoetaliotes 
nebrascensis. 
In another study, Anderson (1961) found little 
correlation between numbers of grasshoppers per 
unit area and the loss of vegetation. He accounted 
for this by the differences in feeding habits of the 
various species comprising the particular grasshop- 
per population. He also stated that considerable 
reductions of yield of vegetation could take place 
during a season without any grazing by either live- 
stock or grasshoppers. 
Nerney (1966) recorded the amounts of forage 
eaten or cut off by grasshoppers in Arizona on both 
sprayed and unsprayed areas. He recorded the 
amount of damage to each plant species contacted 
by a point frame technique. Nerney considered 
damage measurements up to 20 percent, light; from 
20 to 35 percent, moderate; and from 35 to 40 per- 
cent, heavy. He reported that in 1964 Melanoplus 
sanguinipes consumed 92.5 percent of the available 
herbage, mostly Sitanion hystrix (Nutt.) J. G. 
Smith (bottlebrush squirreltail) . 
In 1965, the percentage consumed was low as 
grasshopper populations were noneconomic. 
Nerney and Hamilton (1966) utilized the same 
approach and reported that from August 4 through 
September 8 the amount of grass destroyed by 
average grasshopper populations of 54 per square 
meter, mostly Morseiella flaviventris (Bruner), was 
about 675 kg dry wt/ha. Nerney and Hamilton 
(1967) reported that by September 7th of that year 
percentages of grass consumed by one grasshopper 
per square meter in the untreated area were 2.72 
percent for blue grama, 1.41 percent for curly 
mesquite [(Hilaria belangeria) (Steud.) Nash], 3.38 
percent for three awn (Aristida spp.), 7.68 percent 
for sideoats grama (Bouteloua_ curtipendula 
[Michx.] Torr.), and 2.80 percent for watergrass. A 
survey in October showed the amount of three awn, 
Lehman lovegrass (Eragrostis lehmanniana Nees), 
and sideoats grama blades utilized by grasshoppers 
as heavy (35 to 50 percent). The flowering seed 
heads of sideoats grama and Lehman lovegrass 
were most preferred as food, and the seed crops of 
these plants were 90 to 95 percent destroyed by a 
population averaging 33 per square meter with 
Morseiella flaviventris comprising 74 percent of the 
total population. 
FORAGE LOSSES CAUSED BY INDIVIDUAL GRASSHOPPER 
SPECIES IN THE UNITED STATES 
A number of workers have studied the food con- 
sumption and forage losses caused by individual 
grasshopper species. At least three workers have 
been concerned with alfalfa destruction by grass- 
hoppers (Morrill 1918; Langford 1930; and York and 
Prescott 1947). However, the most significant 
studies regarding rangeland losses have been con- 
ducted with grasshopper species found to be eco- 
nomically important on rangeland since the last 
major outbreaks of the 1930’s. Pfadt (1949b) used 
cages on Wyoming rangeland to determine forage 
reductions per hectare caused by different densities 
of Aulocara elliotti as follows: 
Nymphs per Kilograms of forage 
square meter reduction per hectare 
18 457 
30 550 
42 891 
Because forage production on the study site was 
1,350 kg/ha, a population of 18 grasshoppers per 
square meter would reduce the forage approxi- 
mately 66 percent assuming 50 percent of available 
forage is normally utilized by livestock. 
Putnam (1962) in Canada also used cages over 
natural sod and recorded the reduction in yield by 
the different instars of Camnula pellucida and 
Amphitnorus coloradus as follows: 
