Link directly to photos of adults, nymphs, or eggs.
The Nevada sage grasshopper inhabits the deserts of the far West. It is distributed mainly in Nevada and Utah, but also occurs in adjacent states and the province of British Columbia. The preferred location of the species is in cold desert shrub areas where a variety of shrubs dominate the flora with several subdominant forbs and grasses growing in the understory. These diverse plants appear to serve as food at different times in the season for the Nevada sage grasshopper.
Swarms in Nevada that landed in garden crops completely destroyed plantings of corn, lettuce, onions, radishes, beets, and potatoes. The grasshoppers were not recorded as entering grain fields, but invasion of alfalfa and sweet clover fields caused minor damage.
The Nevada sage grasshopper is a medium-sized species. The live weight of eight migratory phase males collected in Millard County, Utah in 1995 averaged 290 mg and eight females 565 mg (dry weight of males 96 mg, females 186 mg). Live weight of two solitary males collected in Millard County, Utah in 1998 averaged 264 mg and five solitary females 552 mg. Differences in live weight between migratory and solitary grasshoppers of the same sex were statistically insignificant.
An interesting observation was made in the desert of Millard County, Utah of a solitary phase female that fed upon scarlet globemallow. On 19 June 1998, 10:34 a.m. DST (soil surface 105° F, air 68° F, clear), this grasshopper hopped from the ground onto globemallow and crawled around the plant tasting leaves and stems. It finally tasted and fed upon a young fruit for 9 minutes and then hopped back to the ground. This observation prompted examination of eight globemallow plants, all of which exhibited grasshopper injury to leaves, flowers, stems, and fruits. As the Nevada sage grasshopper was the only species of grasshopper feeding on forbs and shrubs inhabiting the site, its feeding on scarlet globemallow, a common plant in the Utah desert, provided evidence that this plant may be an important host.
Unexpected results were obtained in laboratory food preference tests of the Nevada sage grasshopper involving 12 species of plants (two-choice tests). Four plants were preferred: young wheat leaves, dandelion, downy brome, and white sage (Ceratoides lanata). The ubiquitous downy brome, green in spring but dry and brown in summer, may serve as an important host plant for the nymphs. Seven less-preferred (less eaten) species were big sagebrush, gray rabbitbrush, scarlet globemallow, Gardner saltbush, kochia, alfalfa, and barley. One species, tansy mustard, was not fed upon at all.
A definitive study of the food habits of the Nevada sage grasshopper has yet to be made. Results of the food preference tests and several field observations of feeding by adults and of damage by nymphs (dense bands of gregarious nymphs baring the ground of vegetation) provide evidence that the Nevada sage grasshopper is not solely a feeder of shrubs. Like dense hordes of several other species of grasshoppers, they exploit nearly all plants in the habitat rather than starve for lack of a preferred food. Shrubs appear to be a second choice of the Nevada sage grasshopper.
Swarms may be lifted several thousand feet in the air by warm summer updrafts. Sudden strong winds aloft may then transport the grasshoppers long distances. The presence of specimens of this grasshopper on Grasshopper Glacier in Montana in 1949 suggested that a long flight had occurred; the closest outbreak population in that year was in southwestern Oregon 600 miles west of the glacier.
Flushed adults of dense populations have been observed to fly off beyond the observer's vision, but flushed adults in sparse populations usually fly short distances of 1 to 9 feet and at heights of 4 to 18 inches. The adults take off from the ground and usually land on the ground. They fly silently and straight but a few may turn at a right angle near the end of flight. The grasshoppers fly at various orientations to the wind: into the wind, with the wind, and crosswind.
Like the adults, the nymphs of the Nevada sage grasshopper have notable migratory habits. Observations of their migrations were made in 1948 in Nevada. The young nymphs, instars I to III, moved erratically and independently of one another. The older nymphs, instars IV and V, migrated as coherent bands and usually moved northerly in the same direction as the previous year's adults. One band of nymphs was observed to have traveled 200 yards in one day and one-half mile in two weeks.
Adults possess long wings that extend 1 to 7 mm beyond the apex of the hind femur. Ashley Gurney described this grasshopper in 1949 and named it in honor of the late professor of entomology, Arthur G. Ruggles, University of Minnesota. Gurney recognized solitary and migratory phases that differ in body size and wing length with the migratory individuals having larger bodies and longer wings. Small differences in the color of adults exist between the phases. Markings of pronotum and hind femur of solitary adults tend to be gray rather than the bright orange of migratory adults.
The nymphs are identifiable by their structures color, and shape (Fig. 1-5).
1 . Head with face nearly vertical, and colored usually solid tan, antennae filiform; compound eye with diagonal dark bar, light bar on each side of dark bar that extends nearly full width of eye; dorsal area of eye with relatively few large pale tan spots, ventral area with numerous small dark spots.
2. Prominent white or cream-colored crescent beginning on gena below compound eye and extending onto pronotal lobe.
3. Medial and upper marginal areas of hind femur crossed by three alternating dark and light bars. Hind tibia gray and fuscous.
4. Body marked by black stripes and cream and tan patches.
Maturation was studied in the laboratory beginning with adults newly emerged on June 12 to 15, 1995. Source of the nymphs was a population of the migratory phase infesting Millard County, Utah. Two males and seven females were confined in a large cage (11 3/8 in cubed) furnished with a 15 W incandescent bulb turned on during the day and off at night. Day temperatures averaged 82° F and night 72° F. Eight days after becoming an adult a male was observed attempting to mate, but mating was not observed until the 11th day. After 21 days of adulthood, the first egg pod was sifted from the oviposition tray.
Observations of life history made in Smoky Valley, Nye County, Nevada in 1938 revealed eggs of the Nevada sage grasshopper hatching on April 1. By the third week in May practically all of the grasshoppers were adult. Two weeks later (June 1) egg deposition began and continued until the latter part of July when few adults survived. The eggs overwintered and hatched the following spring. The eggs are pale yellow or pearl gray and 4 to 5 mm long. Pods are 1 to 1 3/4 inches long, and contain from 14 to 25 eggs (Fig. 10).
Once a population increases to outbreak numbers, it survives at high densities for a relatively long time. In Nevada an outbreak continued for 14 years from 1938 to 1951; in Millard County, Utah an outbreak continued for a minimum of 7 years from 1989 to 1995, ending only because of a severe drought. Evidently the migration into new habitats each year safeguards the grasshoppers from buildups of predators and pathogens.
Sparse populations of the Nevada sage grasshopper have been briefly studied in Millard County, Utah. Densities of six populations observed along a 30-mile transect south and east of Sevier Lake in 1998 were estimated to range from less than one to one young adult per square yard. The grasshopper's high frequency of occurrence indicated a low density infestation of 250 square miles; perhaps under favorable conditions the grasshoppers will again increase to outbreak proportions. This area was infested by the outbreak of 1989-95, which ended when a severe drought began in July 1995 and lasted through 1996. The nymphs were not observed in the spring of 1996. Presumably most of the eggs laid in the summer of 1995 desiccated and died from lack of water. A few eggs evidently survived in drainages, as small numbers of nymphs were found in such areas in 1997 but none in the upland, which in 1995 was heavily infested with both nymphs and adults.
In western deserts, summer temperatures often exceed 100° F air and 140° F soil surface. To avoid temperatures above their preferendum and tolerance, adults of the Nevada sage grasshopper make behavioral adjustments. In Millard County, Utah, adult grasshoppers in sparse populations were observed to crawl on the ground into the shade of shrubs or to climb several inches into the canopy of shrubs. In dense populations adults climbed to various heights and covered much of a shrub, which often had been defoliated and barked. After temperatures decline in late afternoon, the grasshoppers become active and remain so at the normally and relatively high evening temperatures. At sunset they sit horizontally on bare ground and plant litter. Night activity has not been observed, but it is probable that some adults may move about and even feed.
Gurney, A.B. 1949. Melanoplus rugglesi, a migratory grasshopper from the Great Basin of North America. Proceedings Entomol. Soc. Washington. 51: 267-272.
Next Species in Subfamily: Melanoplus sanguinipes
Previous Species in Subfamily: Melanoplus packardii
List of Species Fact Sheets
Field Guide Contents