Melanoplus sanguinipes (Fabricius)
Wyoming Agricultural Experiment Station Bulletin 912
Species Fact Sheet
by Robert E. Pfadt
Geographic range of Melanoplus
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Widely distributed in North America, the migratory grasshopper, Melanoplus
sanguinipes (Fabricius), lives in a multitude of habitats. It
is a common inhabitant of grasslands and meadows. Host plants include
many kinds of forbs and grasses. Depending on availability of plant
species, it may be either a mixed herbivorous or a forbivorous feeder.
The migratory grasshopper has adapted exceedingly well to western
agriculture. The inadvertent introduction of weeds, plowing of sandy
loam soils of the prairie for the planting of crops, and overgrazing
of rangeland sites have created especially favorable habitats. Introduced
weeds have furnished a nutritious and steady supply of food, plowing
of sandy soils has resulted in wind-blown drifts that have proved
favorable for oviposition, and overuse of rangeland by livestock
has reduced grass cover and led to the invasion of weeds. A more
recent cause of dense populations are the fields of abandoned cropland
that rapidly convert to weeds. All of these sources of outbreaks
make the migratory grasshopper a prime candidate for integrated
pest management. Suggested methods of control include combining
clean culture (weed-free) of crops, elimination of weedy fence rows
and roadside strips, judicious use of herbicides and insecticides,
planting thick stands of grasses in idle cropland, restoring grasses
in depleted rangeland, protecting healthy rangeland from overuse,
and annual monitoring of habitats and populations of the migratory
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The migratory grasshopper, a mixed feeder of grasses and forbs,
is a serious pest of both crops and grasslands. It causes more crop
damage than any other species of grasshopper in the United States.
High densities damage and may even destroy fields of wheat, barley,
oats, alfalfa, clover, corn, vegetables, and ornamentals. It also
attacks vines, bushes, and trees, feeding on foliage, fruit, and
bark. Populations that irrupt on weedy rangeland and in idle cropland
may migrate in massive swarms to infest land miles away. After flight,
the migrants may number from 60-140 per square yard, wreaking havoc
on the vegetation of the landing area - rangeland, crops, or urban
Small grains are especially vulnerable to depredations of the migratory
grasshopper. Losses of a wheat crop may occur in several ways. An
early hatch of grasshoppers may completely destroy newly germinated
seedlings of spring wheat. This occurs when the grasshoppers invade
the crop from heavily infested stubble or roadside. Grasshoppers
may also hatch within the field of growing plants when the crop
is seeded in infested stubble. Gradual defoliation through the growing
season reduces yield and quality of the wheat by depressing weight
of the kernels. Toward the end of the season, defoliated plants
become susceptible to head clipping by grasshoppers, further decreasing
yield. The grasshoppers feed on green areas of the stem close to
the head, causing the head to fall to the ground. A fourth way in
which the migratory grasshopper damages wheat is the invasion in
late summer of second generation nymphs and adults into the edges
of newly emerged winter wheat. The grasshoppers consume the young
plants to ground level. Row after row of seedlings are killed as
the grasshoppers eat their way from the edge toward the center of
a strip or field. This sort of damage occurs in western Kansas and
surrounding regions where strip cropping of winter wheat is practiced.
Dispersal of a light infestation of one grasshopper per square yard
in a fallow strip of wheat stubble to an adjoining field margin
of young growing wheat concentrates the infestation to 55 grasshoppers
per square yard.
High densities of the migratory grasshopper infesting rangeland
seriously deplete forage for both livestock and wildlife. The grasshoppers
not only feed on native forbs and introduced weeds but also on valuable
forage grasses. In the desert prairie of Arizona where this species
frequently reaches outbreak numbers, the grasshoppers damage blue
grama, curly mesquite, red sprangletop, squirreltail, and
stinkgrass as well as a variety of forbs and weeds. In the mixedgrass
prairie the migratory grasshopper attacks several native grasses
including blue grama, western wheatgrass, bluegrasses, and sand
dropseed. A severe outbreak of the migratory grasshopper occurred
in the mixedgrass prairie of South Dakota from 1937 through 1939
and an unusual but severe outbreak occurred in the bunchgrass prairie
of British Columbia during 1944. In the latter case populations
destroyed 70 to 80 percent of grasses on the open range.
Much variation in size of the migratory grasshopper exists among
specimens taken from different habitats and regions. Live weights
of males collected from a ranch roadside in eastern Wyoming averaged
338 mg and of females 442 mg (dry weights 112 mg and 151 mg, respectively).
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Examinations of gut contents show that the migratory grasshopper
is usually feeding on several species of plants growing in its habitat.
This behavior is important in its ecology because laboratory studies
have demonstrated that a mixed diet affords individual grasshoppers
better nutrition. Although polyphagous, the migratory grasshopper
selects host plants from its habitat. Preferred foods include dandelion,
tumble mustard, wild mustard, pepperweed, western ragweed, downy
brome, Kentucky bluegrass, barley, and wheat. Nymphs and adults
ingest dry materials lying on the ground surface including plant
litter, cattle manure, and bran flakes.
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The migratory grasshopper, as the common name implies, often disperses
and migrates. Many accounts of adults swarming have been published,
although there are few records of nymphal migration and still fewer
accounts of adult migration in the absence of mass swarming. Recent
research has revealed that migratory behavior is inherent and regularly
displayed, although considerable variability occurs among populations.
The greatest degree of migration has been found in populations inhabiting
areas where resources are patchy and unpredictable, as in Arizona
and New Mexico. The least degree of migratory behavior was detected
in a population inhabiting a relatively lush and stable environment
The older nymphs, third to sixth instars, may migrate as far as
10 miles but usually the distance is less than 5 miles. The nymphs
travel together in a band at rates of around 0.1 mile per hour.
Adults are highly migratory in their prereproductive stage. Swarming
occurs on clear days when temperatures approach 80°F and
winds are gentle and intermittent. Migrants take off into the wind
and then turn around and fly with the wind at speeds of 10 to 12
miles per hour. They usually begin flight in late morning, fly during
the middle of the day, and alight in the afternoon to feed and rest.
With favorable conditions the following morning, they continue their
migration. From trials of marked adults, individuals are known to
travel 30 miles in a day and probably fly much farther. In 1938
one record of migration indicated a swarm averaged 66 miles per
day for four days, flying from Highmore, South Dakota to Beach,
North Dakota. The longest migrations recorded in 1938 were made
by swarms that traveled from northeastern South Dakota to the southwestern
corner of Saskatchewan, a distance of 575 miles.
Flights of the migratory grasshopper have been designated as low
flights (25 feet or less above the ground) or high flights (more
than 25 feet above ground). The high flights occur at various elevations.
Pilots of observation aircraft in the grasshopper control program
have encountered swarms flying 1,000 feet above ground and pilots
of ferrying aircraft have encountered swarms 2,000-3,000 feet above
ground. Pilots of commercial aircraft have reported encountering
swarms at all elevations up to 13,000 feet above sea level (about
8,000-9,000 feet above ground).
Migrating or milling swarms can be observed by cupping a hand over
one eye and looking toward the sun with the other. The flying grasshoppers
reflect the sun's rays and this shimmer of light can be seen at
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Figures 1-5. 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 4-6 mm FL 2-2.9 mm AS 12-13.
Second Instar: BL 6-8 mm FL 3-4.3 mm AS 15-17.
Third Instar: BL 8-11 mm FL 5.5-6.1 mm AS 18-20.
Fourth Instar: BL 11-16 mm FL 7.6-8.6 mm AS 21-22.
Fifth Instar: BL 16-23 mm FL 10-13 mm AS 22-24.
Figures 6-10. Appearance
of the adult male and female, cercus, note notch, and egg
Adult Male: BL 20-26 mm FL 11-12.5 mm AS 24-27.
Adult Female: BL 20-29 mm
FL 12.3-14 mm AS 25-27.
Fig. 8, Side view
of end of male abdomen.
Fig. 9, End view of
male abdomen, showing notch in the subgenital plate.
Fig. 10, Egg pod and
exposed eggs in bottom of broken egg pod.
The migratory grasshopper, Melanoplus sanguinipes (Fabricius),
is a medium-sized representative of this large genus. Adult males
(Fig. 6) are easily identified by the shape of the cercus (Fig.
8), the notch of the subgenital plate (Fig. 9), and the node or
bump on the mesosternum. The females (Fig. 7) are slightly larger
than the males and can be associated with them and distinguished
by their similar color patterns. The hind tibiae are blue green
The nymphs (Fig. 1-5) are identifiable by their color patterns:
- Compound eye with many light spots, narrow brown bar across
- Narrow pale yellow crescent on gena below eye and continuing
on pronotal lobe to principal sulcus.
- Hind femur with dorsal black stripe cut in middle by light bar;
a light bar on each end.
- Hind tibia of first instar fuscous with pale basal ring; hind
tibia of other instars pale blue green or reddish without pale
- General color of body tan or gray, few light green.
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The migratory grasshopper is an early-hatching species, appearing
on rangeland about one week after the bigheaded grasshopper begins
to hatch. Several environmental factors, especially soil temperature
and moisture, affect the exact timing and duration of hatching.
Hatching starts first along open south slopes, in fields and rangeland
with little vegetative cover, and in sandy soils. The duration of
hatching is shortened by uniform soil and vegetation and high temperatures,
and may be completed in three weeks. Hatching is retarded by heavy
clay loam soils and by tall vegetation that shades the ground. A
mosaic of these conditions in an area, as well as below-normal temperatures,
may extend the hatching period to six weeks. For complete embryonic
development the eggs require 527 day-degrees above a threshold of
50°F soil temperature. Under favorable conditions 80 percent of
development occurs during the summer that the eggs are laid and
20 percent the following spring. In warmer areas of the West, as
in Kansas, the migratory grasshopper produces a smaller (less numerous)
second generation each year. The majority of eggs of the first generation
enter diapause and hatch the following year.
Duration of embryonic development and stage of embryonic diapause
are greatly influenced by the climate of the occupied area. Grasshoppers
from warmer environments tend to diapause at early stages of embryonic
development while grasshoppers from cooler environments diapause
at later stages. This seeming paradox is due to populations evolving
adaptations to prevailing lengths of season.
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Nymphs grow and develop during late spring when days are long,
weather is usually warm, and food plants are green and abundant.
Under these favorable conditions the young grasshoppers pass through
the nymphal stage in 35 days. Cool weather, however, may lengthen
the nymphal stage to 55 days. Nymphal instars range from five to
six; the females usually require the larger number.
A study of six populations of the migratory grasshopper residing
in habitats lying along an altitudinal gradient in California revealed
significant variations in nymphal period and other life cycle parameters.
Both nymphal development and adult maturation were accelerated at
high altitudes relative to sea level. The phenological differences
were attributable partly to environment and partly to genetic divergence
of the populations.
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Emergence of adults begins the first part of summer and may continue
for three or four weeks. The first adults to emerge have the best
chance for reproductive success. At this time there is likely to
be an abundance of green food plants to provide the nourishment
necessary for rapid egg production. In addition, the first eggs
laid will usually experience more favorable soil moisture and have
a longer time to reach an advanced developmental stage before entering
The females have a preoviposition period of two to three weeks.
During this time they increase in weight, mate, and mature their
first group of 18 to 24 eggs. The male is able to recognize a mature,
virgin female and performs a short courtship in which he waves his
antennae and vibrates his hind femora before he makes a sudden copulatory
leap onto the female. A mated female oviposits about six days later
and takes nearly an hour to lay a clutch of eggs. Healthy adults
copulate many times during the reproductive period.
The females deposit their eggs on rangeland among the roots of
blue grama or other grasses. In cropland they often deposit them
around the base of wheat stubble or alfalfa. Pods are curved, one
inch long and one-eighth inch in diameter. The top half
of the pod, containing dried froth, is oriented vertically in the
soil and the bottom half, containing the eggs, is oriented diagonally.
The midpoint of the clutch is three-fourths inch below the soil
surface. Eggs have a banana-like shape, are 4.5 mm long, and pale
yellow or cream colored (Fig. 10). Under laboratory conditions,
a long-lived female may produce as many as 20 pods and a total of
400 eggs. The average fecundity in nature is unknown, but it may
not be more than 20 eggs.
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The population ecology of the migratory grasshopper has received
much study by scientists in Canada and the United States. Their
findings indicate that the two most influential factors affecting
population growth of this grasshopper are weather and food plants.
Although the species feeds on a large variety of plants, a limited
number are particularly favorable for survival, growth, and reproduction.
The migratory grasshopper has a great capacity for increase. Large
populations develop in disturbed or cultivated land such as weedy
rangeland, stubble of small grains, reverted fields, and roadsides.
In a favorable year, a noneconomic population of three adults per
square yard can reproduce exponentially so that in the next year
the population may reach an outbreak density of 30 adults per square
yard. Over a period of several favorable years, densities may reach
enormous levels. In 1938 in northeastern South Dakota, densities
of the migratory grasshopper reached 1,500 to 8,000 nymphs per square
yard in cropland, idle land, and weedy rangeland. Less than ideal
weather and natural enemies (predators, parasites, and diseases)
usually keep populations from increasing to such an extent. Densities
normally range from zero to nine nymphs and zero to three adults
per square yard.
Weather is important to the health of this grasshopper and consequent
population growth. An early, mild spring allows the nymphs to flourish
and a large percentage to become adults. On the other hand, cool
wet weather and heavy rains in spring cause much mortality among
young nymphs. A mild fall with intermittent rains keeps food plants
growing and lengthens the longevity of adults, which allows them
to continue reproducing.
The migratory grasshopper resides, usually in small numbers, in
all types of grassland habitats. During outbreaks of grass-feeding
species on good-condition rangeland, the migratory grasshopper is
present in the assemblage at subdominant densities of 0.1 to 3 young
adults per square yard. This is in contrast to its often dominant
position in weedy depleted rangeland, where it reaches densities
of 20 to 60 or more young adults per square yard. The latter densities
exhaust the forage, inducing the grasshoppers to take wing and migrate
to "greener pastures."
A study of a severe outbreak of the migratory grasshopper in northeastern
South Dakota revealed a gradual increase in density from 1934 to
1936. In the spring of 1937 very severe infestations of nymphs (80
plus per square yard) hatched and survived in many sites. From these
sites adults spread throughout the area. Unusually warm weather
in September and October allowed the females to lay over an extended
period, producing as many as 8,000 eggs per square yard in idle
land and depleted rangeland. This extraordinary reproduction resulted
in an enormous outbreak during 1938 that eventually led to mass
flights of the young adults. Because of the migrations, the outbreak
expanded and continued through 1939. It ended in 1940, due, at least
in parts of the extensively infested area, to a cool, wet spring
that caused high mortality among the nymphs.
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The migratory grasshopper is normally active during the day and
inactive at night. In rangeland habitats most nymphs and adults
spend the night resting horizontally on the ground. A few, however,
climb vegetation and rest vertically head up at heights of 8 to
24 inches. When the rising sun strikes them in the morning, they
adjust their positions to receive the full benefit of the warming
rays. They may bask either on the ground or on vegetation. The common
orientation is to turn a side perpendicular to the sun's rays and
lower the associated hindleg to expose the abdomen. After basking
for approximately two to three hours they become active, walking
about and feeding. Later in the day they have been observed to mate
and oviposit. When soil temperatures rise, those occupying bare
ground may stilt. As temperatures rise still further (soil approximately
130°F, air 90°F at 1 inch level) many individuals climb vegetation,
often the stems and culms of western wheatgrass, to heights of 2
to 8 inches. When temperatures moderate in late afternoon, they
again become active, pottering, feeding, mating, and ovipositing.
Before taking their nighttime positions, they bask for a second
time. J. R. Parker (1884-1972), a renowned student of grasshopper
biology, has described in detail the influence of temperature on
the daily activities of the migratory grasshopper (Montana Agr.
Exp. Stn. Bull. 223, 1930).
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See list of selected field guide references. In grasshopper literature
the scientific name of the migratory grasshopper has been given
as Melanoplus mexicanus (Saussure), later Melanoplus bilituratus
(Walker), and finally Melanoplus sanguinipes (Fabricius).
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