Orphulella speciosa (Scudder)
Wyoming Agricultural Experiment Station Bulletin 912
Species Fact Sheet
by Robert E. Pfadt
Geographic Range of Orphulella
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The slantfaced pasture grasshopper ranges widely in North American
grasslands from east of the Rocky Mountains to the Atlantic Coast
and from southern Canada to northern Mexico. The species is most
abundant in upland areas of short grasses in the tallgrass and southern
mixedgrass prairies. In the shortgrass prairie of Colorado and New
Mexico, it inhabits mesic swales. Generally preferring mesic habitats,
its center of distribution appears to be in the tallgrass prairie
where its populations often become numerically dominant. In eastern
states this grasshopper occurs principally in relatively dry upland
and hilly pastures with sandy loam soil and often becomes abundant
and the dominant species.
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The slantfaced pasture grasshopper is a common, often numerically
dominant, species in the tallgrass prairie region. Populations fluctuate
in density increasing during a series of dry years along with other
grassland species. Because it feeds almost exclusively on grasses,
it contributes to the overall damage of forage by an assemblage
of grass-feeding grasshoppers. In western Iowa during the outbreak
of 1934 to 1937, it, in concert with Ageneotettix deorum
and a few less numerous species, destroyed all green vegetation
in bluegrass pastures. Assemblages ranged from 30 to more than 100
per square yard. Because the slantfaced pasture grasshopper is a
small species, about half the size (weight) of A. deorum,
it presumably eats less and causes less damage to forage. Live weight
of adult males collected in Comanche County, Kansas, 29 August 1997,
averaged 86 mg and adult females 173 mg (average dry weight of males
28 mg, and of females 58 mg).
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The slantfaced pasture grasshopper is a general grass feeder, exhibiting
some preferences among species of grasses. It usually feeds on grasses
in proportion to their availability. Examination of crop contents
of grasshoppers collected in the tallgrass prairie of eastern Kansas
revealed that the common plants ingested were blue grama, sideoats
grama, Kentucky bluegrass, little bluestem, and big bluestem. Because
this grasshopper prefers to inhabit areas of short grasses, mowed
fields, and heavily grazed pastures, a large proportion of crops,
16 to 27 percent, contained blue grama and Kentucky bluegrass. Fragments
of other grasses detected in crops included buffalograss, hairy
grama, prairie junegrass, western wheatgrass, tall dropseed, sand
dropseed, Leibig panic, Scribner panic, switchgrass panic, prairie
sandreed, reed canarygrass, prairie threeawn, stinkgrass, and yellow
bristlegrass. Fragments of three species of sedges were also found:
Penn sedge, needleleaf sedge, and fieldclustered sedge. Unidentified
fungi were present in 6 percent of the crops of grasshoppers from
Kansas and 8 percent from North Dakota. A few crops contained forbs
and arthropod parts. Because of this grasshopper's wide distribution,
it no doubt feeds on many other species of grass. In Michigan it
has been observed to feed on Canada bluegrass (Poa compressa),
arrowfeather threeawn (Aristida purpurascens), and poverty
oatgrass (Danthonia spicata).
In a small patch of short grass within the tallgrass prairie of
Comanche County, Kansas, two observations were made of method of
feeding. On 24 August 1997 at 10:30 a.m. DST (temperature 1 inch
above the ground was 79°), a pair in copulo hopped onto the
top of blue grama and landed horizontally. After five minutes of
basking, the female cut through a leaf, held onto the detached portion,
and began to feed on the cut end. She fed briefly, crawled a short
distance on top of the grass, and began to bask again. A second
female was discovered resting horizontally on the top of a blue
grama plant, stirred and oriented itself diagonally, and then began
to feed on the tip of a leaf.
Because of the scant number of observations of feeding in nature,
several observations were made in a terrarium stocked with turf
of blue grama, western wheatgrass, and bare soil. Adults jumped
or climbed onto the blue grama and fed vertically, head-up on the
edge of a leaf, and moved up the leaf ingesting about 1/8 inch of
leaf edge at a time. Thin edges of the attacked leaves were left
standing. In another cage a female jumped onto the base of an 8-inch
green leaf of downy brome and began to feed from a vertical head-up
position on the edge of the leaf. Eating upward on the leaf, the
grasshopper continued feeding for 18 minutes and then ceased. During
this time the female consumed green leaf tissue 2 3/8 inches long
by 1/8 inch deep and caused a gouge in the leaf of these same dimensions.
A residual edge of 1/8 inch width was left standing. Occasionally
a leaf was cut through; the grasshopper held onto the detached section
with the front tarsi, eating the green material completely and dropping
the yellow, dry tip. Adults were also observed to feed head-down
on leaf edges.
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The slantfaced pasture grasshopper possesses long wings that allow
it to disperse widely. In Lincoln, Nebraska one male and seven females
were captured at night at electric lights 1 July 1921 indicating
that these adults dispersed from surrounding tallgrass prairie.
As valuable as such collections are in providing evidence of dispersal
and migration, they leave several pertinent questions unanswered,
especially grasshopper densities and meteorological data of the
beginning, duration, and ending of flight. Of considerable significance
is the swarming of populations in the New England states.
Flushed flight is silent, often straight, but sometimes circular,
for distances of 1 to 4 feet and usually at heights of 4 to 12 inches.
Flushed flight, however, may be as high as 5 feet (1 of 16 observations).
Flights were chiefly crosswind but one was into a variable wind
that ranged from 3 to 10 mph.
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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 4.3-4.8 mm FL 2.2-2.4 mm AS 11.
Second Instar: BL 5.8-6.2 mm FL 3-3.1 mm AS 14-15.
Third Instar: BL 8.7-9 mm FL 5.7-6.2 mm AS 17-18.
Fourth Instar: BL 9.3-12.5
mm FL 5.4-7.9 mm AS 18-20.
Fifth Instar: BL 9.9-14 mm FL 7.5-9.4 mm AS 19-22.
Figures 6-10. Appearance
of the adult male and female, head, egg pod & distiguishing
Adult Male: BL 13-15 mm FL 8.7-10 mm AS 19-22.
Adult Female: BL 16.5-19.5 mm FL 9.5-11.7 mm AS
Fig. 8, Lateral carina
of pronotum incised once.
Fig. 9, O. speciosa
egg pod and broken pod to show eggs.
Fig. 10, Dorsal view
of head and pronotum of Orphulella speciosa and O.
pelidna showing two characteristics for separating the
(Adapted from a drawing by Daniel Otte).
The slantfaced pasture grasshopper is a small, long-winged species
with a variety of color patterns of brown, tan, and green (Fig.
6 and 7). Specimens are usually spotted and marked with brown and
black. Some individuals bear much green while others are entirely
tan and brown. The face is strongly slanted. The antennae are filiform.
Compound eyes are tan with fuscous spots and markings. Behind each
eye on the side of the head is a broad fuscous band, above it a
thin black line, and above the latter a light line often colored
ivory. A second species, Orphulella pelidna, inhabits the
prairies east of the Rocky Mountains in greater abundance than O.
speciosa. The two species can be distinguished from one another
by structural differences. The slantfaced pasture grasshopper, O.
speciosa, has a small semicircular depression of the vertex
that is closer to the front and the lateral carinae of the pronotum
incised once (Fig. 8 and Fig. 10). O. pelidna, a larger species,
has a larger semicircular depression set farther back and the lateral
carinae incised twice, occasionally three times (Fig. 10).
The nymphs are identifiable by their shape, structures, and color
patterns (Fig. 1-5).
1 . Head. Compound eyes tan and spotted brown; face strongly slanted;
antennae of instar I terminally expanded, antennae of instar II
flat and terminally pointed, antennae of instars III to V filiform;
semicircular depression of vertex located close to front of fastigium;
head of instars I and II with patterns of green, of instars III
to V with patterns of tan, brown, green, and fuscous.
2. Lateral carinae of pronotum incised once, colored ivory, sometimes
green on metazona in older instars; hind femur with medial and upper
marginal areas of instars I and II tan, of instars III to V fuscous;
lower part of medial area and lower marginal area pale gray. Thorax
of instars I and II with patterns of green, of instars III to V
patterns of tan, brown, green, and fuscous.
3. Abdomen in instars I and II green with darker green band on
each side that runs forward on lateral lobe and side of head to
eye, in instars III to V the lateral band is fuscous.
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The slantfaced pasture grasshopper is a late-developing species
hatching about the same time as Phoetaliotes nebrascensis,
a common coinhabitant of the tallgrass prairie. In the Flint Hills,
Kansas (elevation 1,200 ft), hatching of the slantfaced pasture
grasshopper began 16 May 1957-59 and 22 May 1976-78. The hatching
continued for four to six weeks. In Comanche County, southcentral
Kansas (elevation 2,000 ft), hatching began 10 June 1993. In northcentral
Colorado (elevation 5,750 ft), hatching began in mid June 1958-60
and in eastem Montana (elevation 2,000-3,000 ft), 25 June 1950-51.
In the Flint Hills in 1976-78 the period of hatching ranged from
20 days in the south to 47 days in the north. In the north some
eggs were still hatching when some instar-V nymphs were nearly ready
to become adults.
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Nymphs of the slantfaced grasshopper develop through five instars
to reach the adult stage. Several studies of the life history conducted
in the Flint Hills of Kansas indicate a nymphal period of 42 to
48 days, as determined from date of first hatch to first adults.
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Adults usually remain in favorable habitats of short grasses where
they have developed as nymphs. Here they mature, mate, and reproduce,
persisting generation after generation, frequently fluctuating in
density. In the Flint Hills of Kansas adults first appeared 2 July
1957-59 and 5-9 July 1976-78 and in Comanche County, Kansas 17 July
1997. Near Boulder, Colorado adults first appeared by mid July 1958-60
and in eastern Montana by 5 August 1950-51. The peak of abundance
of adults in the Flint Hills occurred in August.
Courtship of females by males was observed on the George Reserve,
Michigan and in Southwestern Quebec. Males may court females by
stridulating, making a faint ticking sound, repeated three to ten
times. Males stalk moving females slowly and stealthily and when
close enough, pounce on them without signaling. After the pair coupled,
any disturbance or stirring of the female induces the male to stridulate,
which keeps the mating pair together. In Comanche County, Kansas,
23-25 August 1997, pairs in copulo were observed from 9:22
a.m. to 2:20 P.M. (the time limits of the observations). The grasshoppers
appeared to be in a mating frenzy. Of 60 grasshoppers observed 18
were of single individuals and 21 were of copulating pairs.
Oviposition has not been observed in nature. A clue to location
of pods was obtained in a laboratory terrarium furnished with buffalograss
turf and bare soil. Three females deposited six pods in the small
bare spaces between grass plants and none in the large bare areas.
None of the pods was attached to roots of the grass. This location
of pods among shortgrass plants would make the discovery of ovipositing
females in nature difficult. The pods measure 13/16 inch long and
contain from 10 to 13 eggs each (Fig. 9). Eggs measure 3.5 to 4.1
mm long and are pale yellow when laid becoming brown as they age.
The eggs are deposited in summer, overwinter, and hatch the following
year in late spring.
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In favorable dry years, populations of the slantfaced pasture grasshopper
increase to outbreak densities. The shortgrass upland areas of the
tallgrass prairie are especially prone to harbor large numbers.
In 1935-36 this grasshopper and Ageneotettix deorum irrupted
in pastures of western Iowa. Populations of the two ranged from
30 to more than 100 per square yard. In many of the pastures all
green vegetation was eaten to the ground by the first of July and
all new shoots were consumed as fast as they appeared. The scarcity
of food induced populations to disperse, presumably to seek better
grazing. Several studies of grasshopper populations inhabiting the
tallgrass prairie of the Flint Hills, Kansas, revealed that the
slantfaced pasture grasshopper is a characteristic species. Frequently
it is the most abundant species of assemblages, at other times the
second most abundant after such species as Ageneotettix deorum,
Mermiria bivittata, Melanoplus femurrubrum, Melanoplus
sanguinipes, or Phoetaliotes nebrascensis. The studies
revealed that the peak of adult density of the slantfaced pasture
grasshopper occurred the first or second week of August and then
declined at a high rate of daily mortality (approximately 9 percent).
In contrast, daily mortality rate of younger grasshoppers (late
nymphal and early adult) amounted to only 2 percent.
That this grasshopper prefers to inhabit sites of short grass was
evident in grassland of Comanche County, Kansas. On 25 August 1997
a population inhabiting a 300 square foot patch of blue grama and
buffalograss reached 14 adults per square yard. In surrounding tallgrass
the adults numbered less than one per square yard. The predominant
tall grasses were interspersed with other patches of short grasses,
which were also populated abundantly with adults of the slantfaced
pasture grasshopper. In Oklahoma and South Dakota, entomologists
have observed the dispersal of large numbers of adults into freshly
mowed roadsides. These tracts of land bear not only shorter, but
also greener and more succulent vegetation.
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The slantfaced pasture grasshopper is a phytophilous insect preferring
to rest on vegetation, principally grasses, day and night. At night
in its preferred habitat of short grasses, it appeared to rest 2
to 3 inches high on stems and leaves of blue grama and buffalograss
(4 to 6 inches tall). Hidden by the dense grass leaves, the grasshoppers
are difficult to locate and to observe their positions and orientations.
Approximately two hours after sunrise, about 9 a.m. DST, they climb
up grass stems and bask. Their usual position is resting on grass
leaves at a 45° angle with their dorsum and a side in the sun. A
few individuals have been found sitting in the sun on dry cattle
dung. Basking may last for two hours before other activities begin.
Pairs in copulo have been observed all day long from 9 a.m.
to 2 p.m. As temperatures rise, the grasshoppers require little
adjustment in orientation since they normally reside in cooler locations
on the tops of short grasses. Some individuals may, however, rest
on tall grass at heights of 9 inches. Presumably at sunset, the
grasshoppers crawl or shinny down on short grasses to their night
time resting places.
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Brusven, M. A. 1967. Differentiation, ecology and
distribution of immature slant-faced grasshoppers (Acridinae) in
Kansas. Kansas Agr. Exp. Stn. Bull. 149.
Campbell, J.B., W. H. Arnett, J. D. Lambley, 0.
K. Jantz, and H. Knutson. 1974. Grasshoppers (Acrididae) of the
Flint Hills native tallgrass prairie in Kansas. Kansas Agr. Exp.
Stn. Research Paper 19.
Evans, E. W. 1992. Absence of interspecific competition
among tallgrass prairie grasshoppers during a drought. Ecology 73:1038-1044.
Gurney, A. B. 1940. A revision of the grasshoppers
of the genus Orphulella Giglio-Tos, from America north of
Mexico (Orthoptera; Acrididae). Entomologica Americana 20 (new series):
Otte, D. 1979. Revision of the grasshopper tribe
Orphulellinae (Gomphocerinae: Acrididae). Proc. Acad. Nat. Sci.
Philadelphia 131: 52-88.
Smith, S. F. 1981. Variation in morphology and coloration
among grasshoppers (Orthoptera: Acrididae) related to geographical
distribution, seasonal occurrence, and plant communities in the
Flint Hills region of Kansas. Ph.D. Dissertation. Kansas State University,
Wilbur, D. A. and R. F. Fritz. 1940. Grasshopper
populations (Orthoptera, Acrididae) of typical pastures in the bluestem
region of Kansas. J. Kansas Entomol. Sec. 13: 86-100.
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