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.
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 mg.
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 leaves.
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 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.
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 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.
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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