FORAGE LOSSES CAUSED BY RANGELAND GRASSHOPPERS 3 
conditions, grasshoppers may be responsible for 
increases in forage production over a period of 
years. Mitchell and Pfadt (1974) pointed out that 
grazing insects such as grasshoppers influence 
aboveground plant productivity by producing unas- 
sorted organic litter (fecal production plus de- 
stroyed material). They estimated that 20 adult 
Melanoplus sanguinipes (F..) per square meter could 
produce 29 g/m? of unassorted litter over 3 weeks. 
Approximately the same amount was produced by 
20 adult Aulocara elliotti (Thomas) per square 
meter and 10 Melanoplus foedus Bruner per square 
meter. 
About half of some 187 grasshopper species oc- 
curring in California can be classified as rangeland 
species (Middlekauff 1958). Cowan (1958) reported 
about 60 species occurring in the United States as 
being economically important, with 5 attacking 
crops and ‘55 important on rangeland. Hebard 
(1938), on the basis of abundance, listed 17 species 
as injurious on pasture and rangeland in Oklahoma. 
Twelve species were reported as being the most de- 
structive in Canada on rangeland during the 1930's 
when the Canadian prairies were in the midst of a 
widespread and intense drought (Gibson 1938). 
Parker (1952) listed 17 species as being abundant on 
rangeland in Montana, North Dakota, South Da- 
kota, Nebraska, and Wyoming from 1936 to 1952. 
Parker (1954) also stated that 100 species feed on 
range vegetation. However, species present in a 
given location are never present in equal numbers. 
Wilbur and Fritz (1940) found that in Kansas, 
grasshopper populations on the native prairie are 
characterized by the genera Orphulella and Mer- 
miria. They reported that approximately 68 per- 
cent of adult grasshoppers collected were of 4 
species while 16 of the species collected were repre- 
sented by 5 or fewer specimens. Middlekauf (1958) 
studied grasshopper populations on two foothill 
sites in California and reported that four species 
were predominant. Buckell (1945) stated that in the 
1943-44 grasshopper outbreak in British Columbia, 
one species, Melanoplus sanguinipes, was dominant 
and caused damage to forages with little aid from 
other species. Before the outbreak, Camnula pellu- 
cida (Scudder) was the main species of concern, but 
in just one year’s time M. sanguinipes spread from 
its usual habitats and invaded the highest cattle 
range areas where it never before had been re- 
corded in high numbers. However, as Parker (1954) 
pointed out, since as many as 20 species may be 
found living together, nearly all range vegetation is 
subject to attack, despite the specialized feeding. 
Parker (1952) also mentioned that studies in Wyom- 
ing showed that populations build up through slight 
to moderate increases of most major species rather 
than by large increases of a few species. 
Kelly and Middlekauf (1961) pointed out that Dis- 
sosteira spurcata (Saussure) should not be consid- 
ered by itself as having significant economic impor- 
tance in California but along with many other 
species adds its share to the damage caused to the 
rangeland each year. Along with other species, D. 
spurcata would make reseeding of more desirable 
grasses very difficult. 
Several workers—lIsely (1938), Herman and 
Eslick (1939), Anderson and Wright (1952), and 
Brooks (1958) —have noted food preferences for a 
number of rangeland species, mainly from observa- 
tions. Other workers have determined the pre- 
ferred food plants for a number of rangeland spe- 
cies based on crop analysis. Lambley (1967) and 
Campbell et al. (1974) noted food preferences for 
Kansas grasshoppers. Hansen and Ueckert (1970), 
Ueckert and Hansen (1971), Ueckert (1968), and 
Ueckert et al. (1972) reported on food preferences 
for some Colorado grasshoppers. Mulkern et al. 
(1969) listed the food preferences for grasshoppers 
in North Dakota, Kansas, and Nebraska. In Idaho, 
Brusven and Lambley (1971) and Banfill and Brus- 
ven (1973) used crop analysis to determine the food 
habits and preferences of several important range- 
land species. Gangwere (1961) has published the 
most complete study on food selection by Orthop- 
tera. He used field observation, differential feeding 
tests, analysis of crop contents and feca! material, 
and the structure and adaptations of their mouth 
parts to foods to assess food preference for Michi- 
gan Orthoptera. 
These studies and feeding observations have 
resulted in a more accurate determination of eco- 
nomically important rangeland species. Thus, fig- 
ure 1 lists the species that might be considered of 
economic importance as consumers of forage plants 
on rangeland. This list is based on food preferences, 
distribution, abundance in past years of outbreaks, 
and abundance in more recent years. However, the 
species listed in figure 1 are not necessarily de- 
structive every year, and species not listed in fig- 
ure 1 may on occasion cause significant forage 
losses. Table 1 shows the preferred food plants of 
