Boopedon nubilum (Say)
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Distribution and Habitat
B. nubilum continental distribution map >
Wyoming distribution map
The ebony grasshopper ranges widely in the grasslands of the West from Montana to
Mexico. The species lives in several types of grasslands including the mixedgrass,
shortgrass, sand, and desert prairies, preferring to occupy the more luxuriant stands
of these habitats.
The ebony grasshopper at high densities can be a pest of rangeland forage. Injurious
infestations usually consist of an assemblage of grasshoppers in which the ebony grasshopper
is one of several abundant species. Irruptions of the ebony grasshopper occur most
often in the southern mixedgrass and desert prairies and may last for several consecutive
years. The affected region includes the states of Arizona and New Mexico and western
Kansas, Oklahoma, and Texas.
In 1955 a severe outbreak of grasshoppers occurred on rangeland of western Oklahoma
in which four species were dominant: Ageneotettix deorum, Aulocara elliotti, Boopedon
nubilum, and Phlibostroma quadrimaculatum. Rangeland grasshoppers became abundant
again in 1973-79 on 1.5 million acres of prairie in western Oklahoma in which the
ebony grasshopper was again a prominent member of the assemblage.
In 1956 an irruption occurred on the desert prairie of San Rafael Valley, Arizona.
The assemblage of grasshoppers numbered 46 young adults per square yard and consisted
of five principal species. Density of young adults per square yard were estimated
to be 13.4 Boopedon flaviventris, 4.2 Boopedon nubilum, 4.6 Phlibostroma quadrimaculatum,
2.6 Trachyrhachys kiowa, 19 Melanoplus lakinus, and 2.6 Melanoplus spp. The loss of
grass forage due to the whole assemblage of grasshoppers amounted to an estimated
600 lb dry weight per acre. In Arizona the ebony grasshopper has been found also in
cultivated areas of corn, sorghum, and wheat.
The ebony grasshopper is a large species. Live weight of young males collected in
bunchgrass prairie of northcentral Wyoming averaged 580 mg and of young females 1,452
The ebony grasshoopper is a fastidious grass feeder. In the desert prairie of southwestern
Texas, ebony grasshoppers have been found to consume large amounts of blue grama.
Examination of crops of adults revealed that contents consisted of 57 percent blue
grama, 17 percent buffalograss, 9 percent common fallwitchgrass, 8 percent bristlegrass,
6 percent common burrograss, and 3 percent hairy grama. From pastures of the Nebraska
North Platte Agricultural Experiment Station, a huge number of crops (1,379) were
examined to disclose a 72 percent preponderance of western wheatgrass fragments. Other
grasses detected in the crops were: needleandthread, 7 percent; blue grama, 5 percent;
sand dropseed, 4 percent; prairie sandreed, 4 percent; threadleaf sedge, 3 percent;
and witchgrass, 1 percent.
More discriminating than most grass-feeding grasshoppers, ebony grasshoppers in two-choice
tests showed decided preferences for certain species of grasses and refused others.
Young adults collected from a bunchgrass prairie site 1 mile east of Shell, Wyoming
preferred the leaves of blue grama, needleandthread, downy brome, and young wheat.
When these plants were available in two-choice tests, the grasshoppers refused to
feed on western wheatgrass, crested wheatgrass, Kentucky bluegrass, and foxtail barley.
Paired with young wheat (variety Buckskin), the grasshoppers ate less than 5 percent
of young cultivated barley (variety Klages). The observation that this grasshopper
fed heavily on western wheatgrass in central Nebraska but refused it in food preference
tests in Wyoming is perplexing.
Observation of feeding by three instar V females in the Shell, Wyoming site revealed
that they climbed an inch or two onto the grass leaf, bit through the leaf, held onto
the cut section with the front tarsi, and consumed it entirely. While feeding, the
nymph was vertical, head-up on the leaf, but one nymph turned around, head-down, and
fed close to the leaf base. The ebony grasshopper was not observed to clip and waste
Dispersal and Migration
Wings of the male ebony grasshopper are long and functional but the female’s are usually
short and flightless. In spite of the female’s lack of ability to fly, whole populations
can disperse or migrate by walking. Displacements of late instars and adults were
observed in San Rafael Valley, Arizona in 1956, 1965, and 1966. In the wet season
of 1966 the grasshoppers carried out a gradual dispersal, but after denuding their
habitat in the dry seasons of 1956 and 1965, they rapidly migrated across low hills
to other sources of forage.
A small percentage of females possess long wings that may surpass the tip of the abdomen.
Presumably these females are capable of flight. Flying females would account for the
widespread occurrence of the species. Males have already been found to disperse long
distances. An "accidental" male was captured July 1959, 8 miles west of a pasture
north of Boulder, Colorado harboring a resident population. Flushed flight of the
males is swift and strong. They fly straight and silently at heights of approximately
12 inches and for distances of 6 to 9 feet.
The male (Fig.7
) is a strikingly black grasshopper with functional wings (Fig. 9
). The disk of the hind wing is pale blue and the apical area black. The hind tibia
may be entirely black or multi-colored, and either black and red, or cream, black,
and red. The female is a large, pale brown grasshopper with short, nonfunctional wings
). A small percentage of females may possess long wings. The sulci of lateral lobes
of females are black as are the crescents of the hind knees. A few females of each
population are dark brown or black.
The nymphs are identifiable by their shape, structures, and color patterns (Fig. 1-6).
1. Head large with face moderately slanted; face tan, side of the head black, triangular
black spot above base of each antenna, top of head tan.
2. Pronotum without lateral carinae but position indicated by light lines; lateral
lobe with inverted black trianglular marking, upper side 2/3 or less width of lobe,
lateral sides straight, not incurved.
3. Hind femur with dorsal stripe of medial area nearly solid black; tibia with three
rings of pale yellow and three rings of black, sometimes tinged with red.
4. Dorsum with a wide tan band; venter is pale yellow.
The ebony grasshopper is a late-hatching species. In the mixedgrass prairie of eastern
Colorado and western Kansas, the eggs begin to hatch the last of May or the first
half of June, about two to three weeks after Melanoplus sanguinipes
. In Larimer County, Colorado, at an altitude of 5,200 feet, hatching began 22 June
1993. In the San Rafael Valley of Arizona (elevation 5,000 feet) hatching did not
begin until 22 July 1965, about ten days after 1.24 inches of rain fell, providing
the eggs with a good wetting, and in 1966 July 28 ten days after 1.67 inches of rain
fell. In Arizona the ebony grasshopper is classified as a summer-developing grasshopper
along with several other species that delay hatching until rains soak the eggs thoroughly.
Nymphs of the ebony grasshopper develop through five instars. In 1993 in the mixedgrass
prairie of eastern Colorado, the nymphal period took a minimum of 40 days. In the
San Rafael Valley, Arizona ebony nymphs completed development in only 27 days in 1965
and 31 days in 1966.
Adults and Reproduction
Adult ebony grasshoppers usually remain in the same habitat in which they develop
as nymphs. Apparently preferring thick stands of mixedgrass prairie for habitation
and an abundance of green grass for food, they are not prone to wander or disperse
unless food shortages occur. In mixedgrass prairie of Larimer County, Colorado, the
adults begin to emerge from mid to late July. In this study site five adult males
and three adult females, in addition to 57 nymphs, were captured on 15 July 1987,
while on 31 July 1993 only one adult female and three nymphs were captured. The appearance
of adults is delayed in the San Rafael Valley because of the late hatch. The nymphs,
however, develop rapidly and in 1965, adults appeared by 18 August.
Only a few isolated facts are known about the maturation of adults. An examination
of the ovaries of 20 females revealed eggs present 21 days after the adults began
to appear in the San Rafael Valley. Collected from bunchgrass prairie in northcentral
Wyoming, a female fifth instar and two male adults were caged, fed young wheat leaves
(Buckskin), and allowed to reproduce. The female laid a pod of 44 eggs by the age
of 40 days. During her adult lifetime of 62 days, she produced three pods for a total
of 134 eggs. Females caged in San Rafael Valley produced multiple pods that contained
from 38 to 62 eggs each.
Females in San Rafael Valley have been observed to deposit pods in bare soil between
clumps of grass and sod during summer and autumn. The eggs overwinter and hatch the
following summer. The pods are large, 1 7/8 to 2 inches long and 3/16 to 1/4 inch
in diameter. The dark brown eggs are 6.5 to 7.7 mm long. Covered by secretions of
the female, the lower section of the pod is dark brown (Fig. 10).
The ebony grasshopper inhabits western grasslands in company with several other rangeland
grasshoppers. Its widespread distribution places many populations in dissimilar environments
and under different environmental stresses. In southern Arizona, drought and parasites
cause significant mortality. A ten-year study (1956-1965) of the population ecology
of the ebony grasshopper disclosed significant annual fluctuations in density
). Six out of ten years the population was depressed apparently by heavy burdens of
the parasite Neorhynchocephalus sackenii
. This dipterous larval parasite feeds on the internal organs of the grasshopper,
preventing the female from developing eggs and eventually killing its host. Application
of insecticide caused the drastic reduction of density in 1956.
The ebony grasshopper is normally subdominant numerically in an assemblage of rangeland
grasshoppers. Smaller species are usually more numerous, such as Ageneotettix deorum, Opeia obscura, Amphitornus coloradus, and Aulocara elliotti. Because of the large size of the ebony grasshopper, it may, however, exceed the
total biomass of a smaller species.
One record of the ebony grasshopper being numerically dominant occurred in 1995 in
an assemblage inhabiting the bunchgrass prairie of northcentral Wyoming. Four species
of the assemblage were estimated to have the following densities of young adults per
square yard: B. nubilum, 5.2; Aulocara femoratum, 1.2; Ageneotettix deorum, 0.4; and Melanoplus occidentalis, 0.2.
In its northern range, the ebony grasshopper takes shelter at night in canopies of
grasses and low shrubs. Shortly after sunrise, individuals emerge and begin to bask.
They turn a side perpendicular to the sun but have not been seen to lower the associated
hindleg to expose more of the abdomen as do many other species of grasshoppers. Basking
may continue for two hours after which late nymphal females do much stirring, preening
of the compound eyes, vibrating of the hindlegs, and intermittent walking with distances
ranging from 2 to 12 inches. When soil temperatures rise to 90°F and air to 80°F,
at about 9 a.m. DST, the grasshoppers take evasive action. They may remain on the
ground and face directly into or away from the sun or they may seek the shade of vegetation
by crawling into clumps of grass or into the canopy of small shrubs. Feeding has been
observed only three times and only in the evening from 5:30 to 6:30 p.m. Because the
female nymphs were close to molting to the adult stage, they probably were not feeding
with normal duration and frequency. Shortly before sunset the grasshoppers enter shelters
for the night.
Brusven, M. A. 1967. Differentiation, ecology, and distribution of immature slant-faced
grasshoppers (Acridinae) in Kansas. Kansas Agr. Exp. Stn. Tech Bull. 149.
Cooperative Economic Insect Report. 1952-1975. USDA APHIS PPQ Vol. 2-25.
Cooperative Plant Pest Report. 1976-1980. USDA APHIS Vol. 1-5.
Fry, B and A. Joern. 1978. Grasshopper food web analysis: use of carbon isotope ratios
to examine feeding relationships among terrestrial herbivores. Ecology 59: 498-506.
Mulkern, G. B., K. P. Pruess, H. Knutson, A. F. Hagen, J. B. Campbell, and J. D. Lambley.
1969. Food habits and preferences of grassland grasshoppers of the North Central Great
Plains. North Dakota Agr. Exp. Stn. Bull. 481.
Nerney, N. J. and A.G. Hamilton. 1966. Effect of insecticide and parasitism on range
grasshoppers, San Rafael Valley, Arizona. USDA ARS Entomol. Research Division, Grain
and Forage Insects Research Branch. Special Report Z-192.
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