Brachystola magna (Girard)
Wyoming Agricultural Experiment Station Bulletin 912
Species Fact Sheet
by Robert E. Pfadt
Range of Brachystola magna (Girard)
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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.
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In its favored habitat, patches of common sunflower and certain
other forbs, the plains lubber grasshopper behaves as a beneficial
insect by providing some measure of biological control of weeds.
However, large populations inhabiting roadsides and field margins
have invaded gardens in Iowa and cotton fields in western Oklahoma
and the western plains of Texas. The plains lubber grasshopper can
be extremely damaging to young cotton plants; outbreak numbers of
adults have completely destroyed stands. They consume all of the
foliage and leave only the stems. More often the damage has been
limited to 40 or 50 marginal rows. Populations of one adult per
3 feet of row in cotton or two per square yard in vegetation bordering
the field are capable of causing economic damage.
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
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The plains lubber grasshopper is a polyphagous insect feeding on
a variety of forbs and grasses. Examination of crop contents of
68 individuals collected in a weedy field near North Platte, Nebraska
revealed fragments of 16 different species of forbs, four species
of grasses, and numerous arthropod parts. The most frequent plants
encountered were common sunflower, found in 35 percent of crops,
and hoary vervain (Verbena stricta), found in 19 percent.
Nineteen percent of crops contained arthropod parts. A moderate
number of crops contained fragments of western wheatgrass (11 percent),
kochia (9 percent), and prickly lettuce (9 percent). Two to 5 percent
of crops contained fragments of scarlet globemallow, breadroot scurfpea,
Missouri milkvetch, wavyleaf thistle, hoary puccoon, upright prairie
coneflower, downy brome, cudweed sagewort, indianpaintbrush (Castilleja
sessiliflora), horseweed fleabane (Erigeron canadensis),
western sticktight, foothill bladderpod (Lesquerella ludoviciana),
and low lupine (Lupinus pusillus). These diverse food plants
represented nine plant families.
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
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
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
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.
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The plains lubber grasshopper disperses and migrates by crawling
and hopping. Entomologists have frequently observed adults crossing
highways and country roads. Just how fast and how far they travel
have not been determined. It is known that from roadsides and field
margins they invade fields of young cotton 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.
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Figures 1-6. Appearance
of the nymphal instars - their sizes, structures, and color
patterns. Notice progressive development of wing pads. BL=body
length, FL=Hind Femur Length. AS=number of antennal segments
First Instar: BL 9.5-12.5 mm FL4.6-5 mm AS 14-16.
Second Instar: BL 12-16.5 mm FL 6.4-7.6 mm AS 17-19.
Third Instar: BL 16-22 mm FL 8.2-10 mm AS 20.
Fourth Instar: BL 23-24 mm FL 12-13.5 mm AS 22.
Fifth Instar: BL 34.5-47 mm FL 16-19.5 mm AS 23.
Figures 6-10 Appearance
of adult male and female, disk, male and female legs, and
egg pod and eggs
Adult Male: BL 43-52 mm FL 24.5-26 mm AS 23.
Adult Female: BL 44.5-55 mm FL 21-24 mm AS 23-24.
Fig. 8, Inner face
of female hindleg (top) and the larger male hindleg (bottom).
Fig. 9, Colored stripes
and knobs of pronotum
Fig. 10, Egg pod and
The plains lubber grasshopper is a large colorful species (Fig.
6 and 7). The robust adults are flightless possessing only short,
round wings; the tegmina are pink and marked by conspicuous black
dots that occasionally coalesce. The body is strikingly striped
and banded green, brown, and pink. The disk of the pronotum is trapezoidal
and surfaced with a dense number of small knobs and several short
wrinkles (Fig. 8). The hindlegs are large and multicolored; the
male's hind femora are noticeably larger than the female's (Fig.
9); outer side of tibia are pale gray or tan, other sides have hues
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
3. Venter of body usually yellow, ivory, or gray.
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Phenologically, the plains lubber grasshopper belongs to the intermediate
group of grasshopper species. Hatching has been observed to start
in eastern Kansas in mid May, in northern Colorado and in Wyoming
during the first week of June, and in Montana in mid June. In southeast
Arizona hatching appears to be retarded until the summer monsoon
rains first wet the soil. A fifth instar nymph collected 7 August
1982 in San Rafael Valley indicated that hatching occurred the first
part of July.
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.
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Nymphs of the plains lubber grasshopper develop through five instars.
In nature the nymphal period of an individual lasts about 45 days.
Reared in the laboratory and subjected daily to 87.8° F for 14 hours
of light and 78.8° F for 10 hours of darkness, the nymphal stage
lasted 27 days.
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The adult stage of the plains lubber grasshopper is reached commonly
in early summer, allowing an extended favorable time for reproduction.
In eastern Kansas, adults first appear during the last week of June,
in northern Colorado the second week of July, in Wyoming the third
week of July, and in Montana the fourth week of July. The start
of egg laying in Montana has been observed to occur in mid August,
indicating a maturation period of 23 days. In 1901 at Fort Collins,
Colorado, the first adult appeared July 10, mating was observed
July 22, and egg laying began August 1. Oviposition then continues
for approximately 60 days until the end of September for surviving
females. In milder climates some adults survive even longer. In
northeast Kansas adults have been observed during the first week
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.
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The range of the plains lubber grasshopper is widespread in the
West, but its distribution is patchy. Populations inhabit disturbed
sites occupied by forbs, especially common sunflower, a native American
plant. This plant often grows in roadsides and field margins providing
favorable habitats for the grasshopper. 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.
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The plains lubber grasshopper occupying a patch of sunflowers spends
much of each day resting, basking, and feeding on its host plant.
Adults and late instars have been observed in the evening and early
morning roosting vertically on the stems or sitting horizontally
on leaves at heights of 8 to 41 inches. Basking of these grasshoppers
occurs shortly after sunrise when rays of the sun strike their host
plants. Turning their backs perpendicularly to the rays of the sun,
the grasshoppers "dorsal bask." A few individuals "flank
bask" by exposing a side and lowering the associated hindleg.
In a site near Guernsey, Wyoming, basking lasted approximately two
hours. Some individuals were observed to bask on the ground.
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.
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Alexander, G. and J. R. Hilliard Jr. 1969. Altitudinal
and seasonal distribution of Orthoptera in the Rocky Mountains of
northern Colorado. Ecol. Monogr. 39: 385-431.
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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