Wyoming Agricultural Experiment Station Bulletin 912
Species Fact Sheet
by Robert E. Pfadt
Geographic Range of Dissosteira
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The High Plains grasshopper inhabits the shortgrass prairie, a
floral province dominated by shortgrasses, principally blue grama
and buffalograss. In addition, this province supports a moderate
amount of three or four species of midgrasses in any one locality.
Common among these midgrasses are western wheatgrass, needleandthread,
sand dropseed, red threeawn, and galleta hilaria. Also present
in the shortgrass prairie are several sedges, forbs, and small shrubs
along with much interspersed bare ground. The biogeographic map
of the High Plains grasshopper shows an inner area (colored dark
blue) where scouts found both nymphs and adults during the 1934-40
outbreak of the species and an outer area (colored pale blue) where
they collected only adults. During the outbreak, swarms of the High
Plains grasshopper dispersed widely from habitats of their origin.
The species has been recorded infrequently in assemblages of rangeland
grasshoppers during nonoutbreak years, yet it continues to survive
and reproduce in especially favorable habitats. Such a habitat occurs
in Otero County, Colorado, 5 miles southwest of Hawley. The area
is characterized by sandy loam soil (Olney) with a 0 to 3 percent
slope. Readily absorbing rainfall, the soil fosters an abundance
of three midgrasses (sand dropseed, galleta hilaria, and red threeawn)
in addition to the short grasses, (blue grama and ring muhly).
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The High Plains grasshopper can be a pest of rangeland grasses.
During outbreaks enormous numbers completely devour the grasses
in their habitat. Hatching from concentrated egg beds, the young
grasshoppers spread out in all directions from these loci and eventually
consume the grasses of the invaded areas. When the nymphs become
older they march in bands seeking food. In their progression they
completely consume the grasses of the rangeland and any fields of
wheat, barley, corn, or millet they encounter. The adults have a
propensity to migrate in huge, flying swarms and cause forage and
crop destruction wherever they land. During the 1934-40 outbreak,
ranchers whose pastures were infested found it necessary to move
their cattle to distant pastures only to have these destroyed by
alighting swarms. These dire outcomes forced many ranchers to sell
their entire herds.
Described in 1872 by Cyrus Thomas, the High Plains grasshopper
was considered a rare species until migrating swarms were observed
in Colorado in 1890 and the first known outbreak was recorded a
year later (Table 1). The most recent outbreak from 1934 to 1940
was calamitous. Entomologists now recognize that this grasshopper
may also occur as a damaging member of destructive rangeland assemblages.
The High Plains grasshopper is one of the largest species among
those destructive to rangeland forage. Collected in the Hawley site
on 16 July 1997, live weight of males averaged 647 mg and of females
1,371 mg (dry weight: males 245 mg, females 450 mg).
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The High Plains grasshopper is a general grass feeder. Field entomologists
have often reported this grasshopper's damage to short grasses (blue
grama and buffalograss), but it feeds also on midgrasses. In two-choice
preference tests, the High Plains grasshopper fed as well on midgrasses
(sand dropseed, needleandthread, and galleta hilaria) as
on blue grama. Although it fed on western wheatgrass, this host
was not consumed as much as the other midgrasses.
The feeding of five late instar nymphs and 13 adults was observed
in their natural habitat (Hawley, Colorado) during the summer of
1997. Four nymphs and nine adults fed on sand dropseed, one adult
fed on blue grama, and one on needleandthread. One nymph and an
adult were observed feeding on ground litter. Although the grasshoppers
were observed to taste leaves of nearby plants before feeding, no
evidence was obtained of their moving to find particular species
Spring 1997 was very dry in Otero County, Colorado. When the majority
of observations of feeding were made, sand dropseed had been grazed
heavily by cattle and grasshoppers. Plants were short with stems
grazed down to 1 to 3 inches, and most leaves were dry. The grasshoppers
fed chiefly on the short stems that were still green. Evidently
these conditions of sand dropseed made the plants convenient for
High Plains grasshoppers to attack from their usual positions on
The common method of attack by a High Plains grasshopper was to
walk up to a grass plant, taste it, and while remaining horizontal
on the ground surface begin to feed at the tip of a low-lying leaf
or on the stub of a grazed stem. When leaves were higher, the grasshopper
raised up diagonally on the plant at approximately a 45° angle and
began to feed on a leaf at or near the tip. The hindlegs remained
on the soil surface, the midlegs on the plant, and the tarsi of
the front legs handled the leaf conveying it to the mouthparts.
Only once was a grasshopper observed feeding off the ground in the
middle of a grass plant facing head down and feeding on a leaf or
stem. The High Plains grasshopper appeared to be a very thrifty
feeder as no clipping and dropping of leaves were observed. Laboratory
observations revealed that whenever these grasshoppers severed a
leaf, they held on to it and consumed all of the green but dropped
the yellow, dry tissue.
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The High Plains grasshopper is a very mobile insect. During outbreak
years huge numbers of hatching nymphs, up to 2,000 per square yard,
soon crawl away from the egg beds that range in size from one-half
to 200 acres and average about 15 acres. Dispersal usually begins
near the end of the first week after emergence and increases rapidly
as nymphs age. The rate of travel of first instars was clocked at
3 feet per minute, the third instar at 6 to 12 feet, and late instars
at more than 10 feet per minute. In 1937 one band of nymphs was
found to travel 2 1/2 miles in one day. In 1993 and 1997 in Colorado's
Bent and Otero counties, nymphs at low densities of less than 1
per square yard appeared to remain close to their hatching sites.
Soon after transforming to the adult stage, the grasshoppers of
dense populations begin to disperse. On their first flights, they
cover from 25 to several hundred yards at a time and at heights
of less than 50 feet. Later, the adults rise in swarms taking high,
long flights that disperse the grasshoppers widely over great distances.
Swarms appear to fly during both day and night; the lights of cities
attract huge numbers and induce them to land. In 1937, 2,940 adults
were marked with nontoxic paints to determine direction and distance
of migratory flights. Sixteen grasshoppers were recovered 1 to 13
days later and at distances of 17 to 175 miles mainly in a northwest
direction from the point of release. The results indicated that
rate of movement ranged from 10 to 37 miles per day and that the
grasshoppers flew with the prevailing winds. After the grasshoppers
land in distant pastures, they concentrate into populations numbering
about 20 per square yard. Fourteen days later the females begin
to deposit eggs. At this time the adults no longer migrate, but
they make regular low flights of one-half to 3 miles between egg
beds and feeding grounds. Observations of small populations, less
than one per square yard, in Otero County, Colorado in 1997 revealed
that the adults form mating aggregations of approximately one adult
per square yard on one-quarter to one-half acre of land. Three aggregations
approximately 1 mile apart were discovered in an infested area of
6 square miles. As the whole area was not inspected, it is probable
that several other aggregations were undetected.
Flushed flight is usually silent without crepitation, but a soft
rustling of the wings is sometimes audible. Distances traveled ranged
from 1 foot in early morning to more than 90 feet at midday at heights
of 4 inches to 3 feet. The short flights are straight but the long
flights are either straight or zig-zag and circuitous. Toward the
end of a long flight, the grasshoppers may make a right angle turn
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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 7.8 mm FL 3.8 mm AS 13-14.
Second Instar: BL 6.1-8.5 mm FL 3.9-4.5 mm AS 14-16.
Third Instar: BL 9.8-13.4 mm FL 4.7-6.5 mm AS
Fourth Instar: BL 13-15.5 mm FL 7-7.6 mm AS 20.
Fifth Instar: Females BL
18.5-24 mm FL 10.7-11 mm AS 23.
Males BL 23 mm FL 12 mm AS 23-24.
Sixth Instar: Females BL 28-31 mm, FL 14-15
mm, AS 25-26.
Males BL 25-25.5 mm, FL 13-13.6 mm, AS 25.
Figures 7-10 Appearance
of adult male and female, male hindleg, end male abdomen,
and egg pod and eggs
Adult Male: BL 36-44 mm FL 19.2-22 mm AS 24-26.
Adult Female: BL 31-35 mm FL 15.8-17 mm AS 25-28.
Left forewing (tegmen) and hindwing of female.
Dissosteira longipennis egg pod and broken pod exposing
eggs in situ.
A conspicuous insect in the shortgrass prairie, the High Plains
grasshopper is distinguished by its large size, attractive black
hindwings, and quick, elusive flight (Fig. 7 and 8). The hindwings
have a transparent outer margin bordering the large black disk that
widens greatly at the apex and is marked by several large fuscous
spots (Fig. 9). The tegmina or forewings are pale tan with many
large brown spots. The median pronotal crest is notably high and
deeply incised once. The inner side of the hind femur is yellow
with two large dark markings near the middle. The hind tibia is
distinctively golden. Wingspans of males range from 2 1/2 to 3 3/8
inches, and females 3 1/4 to 4 inches.
The nymphs are identifiable by their color, shape, and external
structures (Fig. 1-6).
1 . Head with face nearly vertical; antennae filiform, majority
of segments pale tan, terminal segments dark; lateral foveolae small
and triangular; compound eyes tan or brown with light spots; usually
narrow light band on side of head behind the compound eye.
2. Pronotum with median carina strongly elevated and incised once.
3. Hind femur with medial area tan and often with three transverse
diagonal dark bars, inner medial area tan with two or three black
transverse bars; hind tibia of instars I and II black with pale
yellow annulus located proximally, instar III black and tan or entirely
golden, instar IV, V, and VI golden.
4. General body color tan with brown round spots; venter generally
immaculate cream to yellow.
The high pronotal crest and tan, heavily spotted body are diagnostic
features of the younger nymphs. The golden hind tibia and high pronotal
crest are diagnostic features of the older nymphs.
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The High Plains grasshopper is an intermediate-hatching species;
the first instars appear two to three weeks after Aulocara elliotti
nymphs. In 1939 the first hatch occurred May 2 in Colorado. Because
of an unusually warm spell in the spring of 1939 in eastern New
Mexico and the Texas Panhandle, hatching began two to three weeks
earlier than normal on April 21. In 1997 in Colorado's Bent and
Otero counties, hatching was calculated to have begun on May 14.
The hatching period usually lasts from 11 to 18 days but may be
extended to 30 days by spells of cold weather. In egg beds with
southern exposures, the hatch is sooner and faster than in those
with northern exposures.
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Nymphs develop in late spring when temperatures are warm and grasses
young and green. In 1939, based on the dates of first appearance
of nymphs and first adults, the developmental period lasted 44 to
45 days in Colorado, New Mexico, and the Texas Panhandle. In New
Mexico and Texas the majority of nymphs had five instars, while
in Colorado they had six.
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The first adults of the High Plains grasshopper appear in June.
In 1939 they were discovered June 5 in New Mexico and Texas and
June 15 in Colorado. In 1997 the first adults appeared in Bent and
Otero Counties, Colorado on June 25. Maturation of the females is
lengthy, as they require six to seven weeks before laying their
first clutch of eggs. In 1939 this occurred July 17 in New Mexico
and August 1 in Colorado. Male courtship of females appears to be
brief. Only two observations of this behavior were made in nature.
On 1 August 1997 at 8:35 a.m. DST, a male was discovered walking
on bare ground. He approached within a few inches of a basking female
and began to signal with his hindlegs. The female raised her hindlegs
to reject him, but he persisted in the approach, still signaling.
Within an inch of her, he jumped suddenly and mounted. The female
knocked him off and walked 3 feet away. Caged males have been seen
to signal the females by femur-tipping and vibratory stridulation
followed by sudden leaps onto the females that sometimes end in
a successful mating.
Observations made in 1939 revealed that most egg deposition occurred
between 9 and 12 a.m. when air temperatures ranged from 80° to 90°
F. At the beginning of this period they made shallow holes without
depositing eggs. Later on, they selected bare ground around the
edges of grass plants and dug holes into the soil depositing large
clutches of eggs nearly 2 inches deep. Several males usually attended
the ovipositing female. In a laboratory cage a female took 1 hour
and 5 minutes from the start of drilling to withdrawal of the ovipositor.
Afterward she used her hind tarsi for 1 minute to cover the aperture
with soil particles and debris. In nature, a male mounts the female
immediately after oviposition and mates successfully.
Egg beds occurred in various soil types, but during the 1934-40
outbreak the greatest number were found in sandy loam soil. The
majority of pods were deposited in egg beds, although a few were
interspersed in the extensive areas between them. In the spring
survey of 1939, 187 pods were examined and found to contain an average
of 65 eggs with a range of 32 to 84. The egg pod is large and slightly
curved ranging from 1 to 2 inches long (Fig. 10). The eggs, 4.4
to 5.6 mm long, are pale yellow when laid but eventually turn tan.
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Populations of the High Plains grasshopper irrupt during periods
of drought and above-normal temperatures. Rainfall and temperature
have their greatest influence during the hatching period when the
nymphs are delicate. Numerous observations made during the 1934-40
outbreak revealed that cold, wet weather decimated populations of
young nymphs and warm, clear weather fostered their welfare. When
the nymphs were older, rains had little effect on survival. Biotic
factors reducing populations during the outbreak were predatory
birds, rodents, and insects. These took their toll, yet many adults
survived through August and September and a few into October. A
thorough summary of the life history, ecology, and control of the
High Plains grasshopper was published in 1958 by Claude Wakeland
as USDA Technical Bulletin 1167.
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In spite of its notorious reputation as a strong migratory flier,
the High Plains grasshopper spends most hours on bare ground in
its habitat. In the shortgrass prairie southwest of Hawley, Colorado,
late instars and adults did not seek shelter at night but rested
horizontally on bare ground within an inch of clumps of grass. After
sunset they often crawled short distances, but in the morning before
sunrise they were immobile. In the summer of 1997, ground temperatures
at the Hawley site were approximately 77° F at sunset and 65° F
shortly before sunrise. One-half to one hour after sunrise, the
grasshoppers adjusted their bodies to bask. They rested horizontally
on bare ground, turned a side perpendicular to rays of the sun,
and lowered the associated hindleg to expose more of the abdomen.
In July and August, basking lasted two to three hours, approximately
from 6 a.m. to 9 a.m. DST. During this time individuals may turn
around 180° and continue basking, or they may walk distances of
4 to 6 inches and then resume basking, apparently in a better location.
During the basking period almost all High Plains grasshoppers rest
quietly, absorbing the heating rays of the sun. Toward the end of
this period, a few individuals may walk short distances to find
a host plant and feed. A few males may also start to court nearby
females. Of 18 observations of feeding, seven occurred between 8
and 9 a.m., six between 9 and 10 a.m., four between 10 and 11 a.m.,
and one at 2:51 p.m. DST. Temperatures of the unshaded soil surface
during the period of morning feeding ranged from 85° to 112° F;
shaded air at 1 inch high ranged from 67° to 90° F. The temperature
at the time of the one afternoon observation of feeding registered
130° F at the soil surface and 105° F air. Courting was observed
twice between 8:35 and 8:49 a.m. 1 August 1997, but no pairs in
cap were seen anytime.
In the Hawley site on clear days the ground temperatures rose rapidly
in July and August, reaching 120° F by 10 a.m. DST. Heat induced
the grasshoppers to stilt and to face directly into the sun or to
face directly away from the sun. As temperatures rose further, the
grasshoppers crawled onto the top of short grasses raising
the body about an inch above the soil surface and away from the
surrounding hot bare ground. They assumed a diagonal orientation
on top the short grass facing the sun directly and shading
Observed in low-density populations of less than one individual
per square yard and away from egg beds, the High Plains grasshopper
appears mainly quiescent-little jumping, walking, or flying unless
flushed. After the basking period on 21 August 1997 from 9:20 to
11:08 a.m. DST, four appetitive flights of 15 to more than 50 feet
were observed when ground temperatures ranged from 100° to 123°
F and air temperatures from 77° to 85° F. Appetitive walking (pottering)
was also observed on five different days. Eight observations revealed
movements of 1 1/2 to 15 feet over bare ground; the grasshoppers
usually broke the walk into two or three segments separated by brief
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Wakeland, Claude. 1958. The High Plains grasshopper,
a compilation of facts about its occurrence and control. USDA Tech.
Willis, H. R. 1939. Painting for determination of
grasshopper flights. J: Econ. Entomol. 32: 401-403.
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