10 MISCELLANEOUS PUBLICATION 1348, U.S. DEPARTMENT OF AGRICULTURE 
hoppers has also been compared to utilization by 
livestock. Drake and Decker (1937) estimated that 
12 to 24 grasshoppers (depending upon size) per 
square meter in a 0.4-ha area of bluegrass pasture 
will consume as much forage daily as a cow. Parker 
and Connin (1964) mentioned that even with an 
average of seven or eight grasshoppers per square 
meter the population on 4 ha consumes grass at 
about the same rate as a cow. 
During outbreaks when there may be 36 to 72 
grasshoppers per square meter, all the grass may 
be destroyed. Nerney and Hamilton (1969) reported 
that in 1954 in Arizona 99 percent of the vegetation 
was destroyed by Aulocara elliotti at a density of 50 
to 77 grasshoppers per square meter. Nerney 
(1960) also found the total damage caused by 11 to 
32 grasshoppers per square meter to range from 8 
to 63 percent. 
QUANTITATIVE STUDIES ON FORAGE LOSSES 
IN AREAS OTHER THAN THE WESTERN UNITED STATES 
Several workers have attempted to quantita- 
tively measure forage losses caused by grasshop- 
pers in the laboratory and in the field. A few 
workers have found that grasshoppers have a mini- 
mum influence on vegetation; however, these 
studies have involved grasshoppers that are not 
associated with U.S. rangeland. For instance, Mat- 
sumoto (1971) in Japan determined that a field pop- 
ulation of Parapleurus alliaceus consumed 242 g dry 
wt of Miscanthus sinensis Anders leaves per 100 
m?” in 1968 (1.4 percent of the standing crop in 
August) and 97.6 g dry wt/100 m? in 1969 (0.6 per- 
cent of the standing crop in August). He also added 
that even if the indirect effects of feeding are con- 
sidered, the loss of the primary productivity of M. 
sinensis grassland due to P. alliaceus would rarely 
exceed 5 percent. 
Other workers have determined the amounts of 
forage consumed and assimilated in terms of energy 
units. Smalley (1960) reported on a marsh grass- 
hopper population (Orchelimum fidicinium Rehn 
and Hebard) in Georgia and found that less than 1 
percent of the dominant plant (Spartina alterniflora 
Loisel) was eaten by the grasshoppers. He con- 
cluded that most of the net primary production of 
the marsh is eventually decomposed. Wiegert 
(1965) studied populations of grasshoppers on two 
sites in Michigan, an old field and an alfalfa field. On 
the old field, the grasshoppers ingested 4.8 kcal/ 
m?’/year (less than 0.5 percent of the net primary 
production), while the ingestion by grasshoppers on 
the alfalfa field was 36 kcal/m?/year (approxi- 
mately 2.5 percent of the net primary production). 
Populations at both sites in general ranged from 10 
to 11 individuals per square meter in early summer 
to less than one per square meter in September and 
October. 
Based on studies in Finland with Chorthippus 
parallelus, Gyllenberg (1969) mentioned that when 
consumption versus net primary production is con- 
sidered in the course of time, the part eaten at first 
constitutes a very small percentage of the material 
produced by the plants, but as plant production 
decreases, grasshoppers comprise a regulating fac- 
tor on the new plant biomass produced. However, 
he also concluded that the grasshopper population 
was not a factor regulating the amount of net pri- 
mary production. 
White (1974b) estimated consumption of field 
populations of alpine grasshoppers by using field 
data such as consumption per grasshopper per feed, 
feeding thresholds, the number of feeds in a life- 
span, grasshopper density, feeding preference, and 
vegetation availability. He estimated that instars 4, 
5, and 6 and adults of Paprides nitidus Hutton 
accounted for more than 90 percent of the cumula- 
tive consumption in the total lifespan of the indi- 
vidual. In areas of high grazing pressure, the 
amount of vegetation removed was only 13 kg/ha 
where the total dry matter productivity was esti- 
mated to be 500 to 600 kg/ha. However, the authors 
pointed out that the selective distribution of graz- 
ing activity may contribute to pressure in excess of 
50 percent on some vegetation components. 
White (1974c) surveyed 10 alpine sites in New 
Zealand and compared grasshopper density, con- 
sumption level, vegetation composition, percent 
bare ground, and site aspect. He concluded that in 
most tussock grasslands below 1,200 m, grasshop- 
per grazing pressures are negligible because of low 
grasshopper densities and noncritical levels of veg- 
etation productivity, but in grasslands above 1,200 
m, grazing pressures are of real significance be- 
cause densities are high and crop availability and 
