FORAGE LOSSES CAUSED BY RANGELAND GRASSHOPPERS 11 
production are low. However, most studies have 
shown that grasshoppers and locusts cause consid- 
erable forage losses. 
The most difficult task is to compare results of 
the different research efforts on an equal basis. For 
example, Andrzejewska et al. (1967), in Poland, 
calculated that 10 acridoidea per square meter 
reduced the net primary production 11.9 percent 
during a 9-week period and estimated that grass- 
hoppers destroy nearly five times the biomass they 
consume. 
Rubtzov (1932) concluded that 10 grasshoppers 
per square meter in eastern Siberia would consume 
683 kg/ha of grass for a total loss in that area of 
38,970 t/year. This was based on feeding studies 
that showed that an adult eats 30 to 50 percent of 
its own weight in grass (Bromus inermis Leyss) 
each day, and, during its development, an adult 
individual consumes 20 times its weight. Serkova 
(1961) reported that, in Russia, a grasshopper pop- 
ulation of one to two per square meter in 1958 
destroyed 15.6 percent of the vegetation during the 
growing season, whereas in 1955 a population two 
to three times greater destroyed 30 percent of the 
vegetation. 
Researchers outside of the United States have 
studied forage losses caused by individual grass- 
hopper species. Davey (1954) working with the des- 
ert locust, Schistocerca gregaria (Forsk.), figured 
that males consumed an average of 30.7 g of fresh 
vegetation and females 44.3 g between hatching 
and becoming adults. He also determined that a 
nymph eats approximately its own weight of fresh 
vegetation per day, and an adult roughly one-half 
its own weight per day (approximately 1.0 g). A 
migrating swarm would need to eat at least its own 
weight per day and possibly three times as much. 
Bullen (1966) using these data suggested that a 
fairly typical desert locust swarm (26 m? in area), 
with an area density of 36 locusts per square meter 
and a mean weight per locust of 1.7 g, could con- 
sume at least 1,413 t of fresh vegetation per day. 
The amount damaged, destroyed, and left uneaten 
should alse be considered. He related forage losses 
to grazing by considering that the optimum carry- 
ing capacity in African semiarid desert areas is 
often one cow to 16 to 20 ha and can be as low as one 
cow to 26 ha in the semidesert areas of the Sudan. 
From the known food consumption of the desert 
locust, Bullen estimated that a swarm of 240 per 
square meter could eat as much vegetation per day 
as one native cow (about 11 kg), so that a small to 
medium swarm of about 26 km’ has the grazing 
capacity of 150,000 head of cattle, or about 1,000 
times the ecological optimum carrying capacity of 
the growing area. 
Kaufmann (1965) determined the food consump- 
tion of Euthystira brachyptera (Ocskay) in central 
Europe by offering caged grasshoppers preferred 
and unpreferred food plants. He found six third 
instar nymphs consumed an average of 1.897 g of 
preferred fresh vegetation and 1.736 g of unpre- 
ferred fresh vegetation during a 2-week period 
when the temperature ranged from 20° to 27° C. 
He also found the average daily consumption of 
fresh vegetation by adults at different tempera- 
tures to be as follows: 
Fresh vegetation consumed (mg) 
Temperature °C Male Female 
16 17 28 
18 26 34 
20 23 43 
22 23 51 
24 24 61 
26 36 68 
28 38 84 
30 42 98 
More recently, White and Watson (1972) studied 
food consumption of three New Zealand alpine 
grasshoppers by counting leaves and measuring the 
amount of leaf area destroyed. They determined 
the dry weight consumption for each instar of the 
three species and the number of feeds that occur 
within each instar. The number of feeds (generally 
two per day) is limited by the level of incoming radi- 
ation that is sustained during the day. 
FORAGE LOSSES CAUSED BY GRASSHOPPER POPULATIONS 
IN THE UNITED STATES 
Workers in the United States and Canada have 
assessed forage losses caused by grasshoppers both 
in terms of populations and as individual species. 
Morton (1936) was one of the early workers to 
determine forage losses caused by a mixed popula- 
tion of rangeland grasshoppers. He selected 10 sta- 
tions in various types of range in Montana and 
placed two cages (1 m’) on each site to exclude all 
