Slantfaced Pasture Grasshopper
Orphulella speciosa (Scudder)
Link directly to photos of adults, nymphs,
Distribution and Habitat
O. speciosa continental distribution map
Wyoming distribution map
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.
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).
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.
Dispersal and Migration
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.
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 0. speciosa. The two species can be distinguished
from one another by structural differences. The slantfaced pasture grasshopper,
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). 0. 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
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.
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.
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.
Adults and Reproduction
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
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.
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.
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.
Brusven, M. A. 1967. Differentiation, ecology and distribution of immature
slant-faced grasshoppers (Acridinae) in Kansas. Kansas Agr. Exp. Stn. Bull.
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): 85-157.
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, Manhattan.
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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