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Wyoming distribution map
The plains lubber grasshopper ranges widely on the western plains of the United States and Mexico. It inhabits several types of prairies: shortgrass, mixedgrass, tallgrass, sand, and desert prairies. In these diverse habitats it depends on the presence of certain forbs for its sustenance. It locates patches of host plants along roadsides, field margins, and disturbed rangeland. Patches of common sunflower, Helianthus annuus, are especially attractive to this grasshopper.
Considered an occasional pest of cotton, this grasshopper increased to damaging numbers in 1954, 1959, 1977, and 1979, during a period of 30 years (1951-1980) in Texas.
The plains lubber grasshopper is one of the largest acridids in North America. Collected in Bent County, Colorado from patches of common sunflower, fresh weight of four males averaged 3,935 mg and of five females 4,287 mg (dry weight males 1,188 mg, females 1,292 mg).
In southeastern Wyoming (Platte County along a gravel road in Whalen Canyon), nymphs and adults were observed to feed mainly on common sunflower. Young nymphs attacked seedling plants, which at the time of observation were 3 to 6 inches tall. To feed, the nymphs climbed the plant, adjusted their bodies, and fed at the edges of leaves, eating into the leaf and creating deep gouges. A third instar was observed to feed on the leaf of a 3-inch plant for three minutes. Later in the season, adults attacked the leaves, buds, and flowers of plants now 17 to 32 inches tall. Two adults (one a female, the other unsexed) were observed feeding into the sides and developing seeds of green heads. Each fed for 16 minutes before completing its meal.
Populations inhabiting two sites near Boulder, Colorado were associated with the sunflower, Helianthus pumilus. This leads one to suspect that among the 13 species of Helianthus distributed on the Great Plains, other members of the genus may serve as host plants and support isolated populations. A suspected host species is the prairie sunflower, Helianthus petiolaris, specimens of which were observed to have been defoliated by a small population of the plains lubber grasshopper inhabiting a roadside in Platte County, Wyoming.
A study of the foraging behavior of the plains lubber grasshopper in a southeastern Arizona site confirmed its highly polyphagus behavior. Adults were observed to feed on 21 species of plants belonging to 15 plant families. Feeding bouts were short with the majority lasting less than two minutes, indicating that few suitable food items were present. Preferred plants included Boerhaavia coccinea, Hymenothrix wislizenii, and Gaura coccinea, but feeding bouts were also short on these plants. No common sunflowers were present at this site.
The research in Arizona disclosed a remarkable degree of omnivory and predation by the plains lubber grasshopper. A large part of the diet of 15 closely observed females consisted of animal matter. Foraging on the ground, the females ate incapacitated insects and even captured and ate smaller melanopline grasshoppers.
Laboratory food preference tests conducted in Texas revealed that the plains lubber grasshopper preferred common sunflower, western ragweed, and cotton seedlings. Two-choice tests conducted in Wyoming showed that dandelion, prairie sunflower, and annual sowthistle were also preferred food plants.
Brief observations of hopping behavior of adult females were made on a dirt road at the Guernsey, Wyoming, airport on the afternoon of 31 July 1998. At this time the sun was hidden by clouds, soil surface temperature was 93° F, air temperature 84° F, and an east wind of 4 to 9 mph was present. Unflushed hops of females measured 3 to 4 inches. Flushed hops of two females measured 14 inches each. No data on males were obtained; however, Ernest Tinkham, while studying the ecology of grasshoppers inhabiting the Trans-Pecos region of Texas, observed that male plains lubber grasshoppers could jump 9 feet in a single leap.
The nymphs are identifiable by their color patterns, shape, and external structures (Fig. 1-5).
1 . Head green, tan, or fuscous; antennae filiform and chiefly black, each segment with distal ivory annulus, subocular groove black, instars I and II with vertical ivory bar in front of eye on each side of the frons; compound eyes dark brown.
2. Pronotum: disk and lateral lobes trapezoidal, median carina distinct, black, and entire (uncut), lateral carinae distinct, black and cut once in front of middle, disk banded pink and green with dense number of small knobs (Fig. 8); posterior margin of disk ivory, lateral lobes more or less margined with ivory. Mesonotum smooth and shiny black (see Fig. 1, instar I for exposed mesonotum), in subsequent instars the pronotum overgrows and hides the mesonotum. Metanotum knobbed and colored like rest of body. Hind femur patterned, hind tibia hues of orange in instars I to IV, orange or yellow in instar V.
3. Venter of body usually yellow, ivory, or gray.
Research of the USDA Grasshopper Laboratory has revealed that the eggs of this species require two years of incubation and overwintering before they hatch. In addition to the laboratory evidence, field observations in Montana, Wyoming, and Texas show higher populations in alternate years, which likewise indicate a two-year life cycle.
Little information is available on the site of oviposition, but it appears that females select bare, sandy loam areas in which to deposit their eggs. The pod is large, 1 3/4 to 2 inches long and 3/4 inch diameter in the region of the eggs. It is gourd-shaped (Fig. 10) and contains 20 to 35 large (length 10.1 to 10.8 mm) dark reddish brown eggs.
Biennial populations fluctuate and occasionally reach outbreak proportions. A few reports indicate that one young adult per square yard may be rated as a high density equaling in biomass 11 young adults of Melanoplus sanguinipes. In Texas, outbreak populations bordering cotton fields may concentrate to 10 young adults per square yard. Attrition of adults occurs during the summer. This grasshopper has been shown to be an edible one for predators such as birds, rodents, and carnivores. A scat, probably of a swift fox, Vulpes velox (Say), collected 1 September 1993 from rangeland in Bent County, Colorado contained parts of the plains lubber grasshopper.
As no sustained study of this grasshopper has been made, we know little of its ecology-the factors that cause it to increase in density, the duration of an outbreak, and what factors may cause the decline or crash of an outbreak population.
After basking the grasshoppers adjust their orientation to the sun and for a short time rest quietly on the host plant. Later they stir and begin moving about the plant, feeding, and crawling down head-first to the ground. Mating has been observed to occur on the ground as well as oviposition. While on the ground the adults have been observed to disperse by crawling and to feed on injured grasshoppers. They appear to have a strong disposition to disperse through prairie vegetation traveling in one direction at a relatively rapid speed.
In summer, ground and air temperatures during the middle of the day often rise above the tolerance level of this grasshopper. Temperatures of 110° to 140° F of ground surface exposed to the sun and concomitant air temperatures of 93° to 100° F induce the adults on the ground to move to shade of vegetation or to crawl up 20 inches or higher on a host plant. Grasshoppers that have climbed common sunflowers take positions in the shade, or lacking adequate shade on a defoliated plant, they make a postural response in which they face the sun directly. The rays strike the front of the head while the rest of the body is shielded from the intense rays. On the ground this grasshopper has been observed to stilt, a behavior probably occurring early when temperatures first become excessive.
By late in the afternoon the majority of grasshoppers have returned to host plants, where they rest quietly, perched on main and secondary stems and on leaf surfaces. An odd exception was occasionally noticed in which the adult grasshopper hung onto the edge of a sunflower leaf with the fore and midlegs allowing the body and hindlegs to dangle beneath the leaf.
Bright, K. L., E. A. Bernays, and V.C. Moran. 1994. Foraging patterns and dietary mixing in the field by the generalist grasshopper Brachystola magna (Orthoptera: Acrididae). J. Insect Behavior 7: 779-793.
Burleson, W. H. 1974. A two-year life cycle in Brachystola magna (Orthoptera: Acrididae) with notes on rearing and food preference. Ann. Entomol. Soc. Am. 67: 526-528.
Isely, F. B. 1938. The relations of Texas Acrididae to plants and soils. Ecol. Monogr. 8: 551-604.
Joern, A. 1981. Importance of behavior and coloration in the control of body temperature by Brachystola magna Girard (Orthoptera: Acrididae). Acrida 10: 117-130.
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