Cordillacris crenulata (Bruner)
Link directly to photos of adults, nymphs,
Distribution and Habitat
C. crenulata continental distribution map
Wyoming distribution map
The crenulatewinged grasshopper is a small, grassland species that reaches
its greatest abundance in the shortgrass and desert prairies and in heavily
grazed upland sites of the mixedgrass prairie. Its geographic range extends
westward into the bunchgrass prairie and shrub-grass associations as far
as Nevada and California. It prefers short stands of grass in which blue
grama is dominant and interspersed with bare ground. The species does not
invade the tallgrass prairie nor dense stands of mid grasses in the mixedgrass
The crenulatewinged grasshopper attacks and eats the green leaves of blue
grama, a preferred forage grass of livestock. The grasshopper's presence
in an economically damaging assemblage on rangeland adds slightly to the
total damage. In the northern mixedgrass prairie it has been found to comprise
1 to 4 percent of some outbreak populations. Occasionally it becomes the
most abundant species in an assemblage, with adult densities reaching eight
per square yard. In Montana it has been recorded as causing considerable
damage to threadleaf sedge, and in Arizona it has been observed destroying
young grasses on newly seeded rangeland. However, because of its small
size and generally low densities, it usually is not a serious pest on grasslands.
Live weight of males averages 45 mg and of females 110 mg (dry weight males
15 mg, females 24 mg).
The crenulatewinged grasshopper is a grass feeder, preferring blue grama
whenever it is present in the habitat. In the shortgrass prairie of eastern
Colorado, it fed almost exclusively on blue grama. This grass comprised
over 99 percent of crop contents of instars I to IV and over 96 percent
of crop contents of the adults. Small amounts of needleleaf sedge, red
threeawn, prairie junegrass, and a trace of one forb, tansy aster, were
also found in crop contents.
In Montana the crenulatewinged grasshopper has been observed to feed
heavily on threadleaf sedge in addition to blue grama. In a desert prairie
of southwest Texas, crop contents of this species consisted of 71 percent
blue grama, 7 percent hairy grama, 6 percent buffalograss, 4 percent burrograss,
4 percent of an undetermined grass, 4 percent of flax (a forb), and 2 percent
of fall witchgrass. This grasshopper can live in communities where blue
grama does not occur, subsisting on other grass species. In the mixedgrass
prairie of Wyoming, one observation has been made of its feeding on needleandthread
The method by which older instars and adults of this grasshopper attack
the primary host plant, blue grama, has been observed in the mixedgrass
prairie of eastern Wyoming. A hungry individual appears agitated and crawls
on the ground and over host plants waving its antennae and shaking its
hindlegs. It stops at several blue grama plants and tastes leaves until
it finds one it apparently likes. The grasshopper crawls up the leaf a
short distance, tastes the leaf again, then turns around head down and
backs up toward the tip. It begins to feed on the edge about one-quarter
inch from the tip and proceeds toward the base. It consumes most of the
width, but leaves behind a narrow standing length to which it clings. On
a recumbent or detached leaf lying on the ground, an individual feeds from
a horizontal position.
Dispersal and Migration
A study of local movement by adult crenulatewinged grasshoppers in a habitat
of the desert prairie revealed an average daily displacement of 16 feet
and a maximum of 210 feet. Observations of normal activity of adults in
the mixedgrass prairie of eastern Wyoming indicate that movement is achieved
both by walking and flying. Adults have been observed to walk both in short
bouts of a few inches and to walk as much as 6 feet without stopping. Walking
crenulatewinged grasshoppers wave their antennae and, when they stop, shake
Evasive flights are straight and silent with distances ranging from
2 to 8 feet and with peak heights of approximately 6 inches. The grasshopper
usually takes off from the ground and lands on the ground facing away from
the intruder. No information is available on long-distance dispersal and
migration by this grasshopper.
Adults of the crenulatewinged grasshopper are small and slender (Fig.
5 and 6). The body is cream-colored with brown markings and stripes.
A diagnostic character is the wide, brown, crenulate or scalloped stripe
on each tegmen (Fig. 7). The subocular
groove is edged posteriorly with a narrow brown stripe. On the side of
the head behind each compound eye a conspicuous triangular brown stripe
is present. The upper part of the lateral lobe is brown; the lower is cream-colored.
An anterior cream-colored wedge runs nearly to the top of the lateral lobe
separating the brown postocular stripe from the brown stripe of the lateral
lobe. The hind tibiae are pale gray to yellowish and have a distal dark
Nymphs are identifiable by their shape and distinctive color patterns
(Fig. 1- 4).
1. Head with strongly slanted face; antennae slightly ensiform in instars
I to III, filiform in instar IV. Postocular brown stripe present on side
of head. Dorsum of head with brown medial stripe that is usually divided
by narrow light line. Subocular groove edged posteriorly with a brown stripe.
2. Pronotum with lateral lobe brown on upper half, cream on lower half.
Distinctive cream-colored wedge on upper anterior edge of lateral lobe.
Lateral carinae low but conspicuously cream- colored. Disk of pronotum
with triangular posterolateral markings.
3. Hind femur with medial area brown dorsally and cream ventrally, as
in Cordillacris occipitalis but with greater contrast of colors. Hind tibia
pale gray with a dark annulus distally.
The crenulatewinged grasshopper hatches three to four weeks after the spottedwinged
grasshopper, Cordillacris occipitalis, and belongs to the intermediate-hatching
group of grasshoppers. Eggs probably begin development upon being laid
in the ground in summer. They develop to embryonic stage 18 by fall and
enter diapause at this time. They overwinter protected in soil cells constructed
by the ovipositing females. Eggs lie at a shallow depth in the top one-half
inch of soil. When temperatures rise in spring, development resumes. Hatching
usually occurs in mid May in the desert prairie of Arizona and during the
first half of June in the mixedgrass prairie of eastern Wyoming and the
shortgrass prairie of northcentral Colorado.
The length of the nymphal period ranges from 30 to 43 days and averages
36 days. The period is approximately five days shorter than that of C.
occipitalis. This difference is probably due to warmer temperatures
experienced by the later-hatching crenulatewinged grasshoppers and the
requirement of only four instars to reach the adult stage. A few females
require five instars.
Adults and Reproduction
Adults appear in July in the northern mixedgrass and shortgrass prairies,
and remain in the same habitat in which the nymphs hatched and developed.
Ordinarily, this habitat continues to provide a plentiful supply of green
leaves of its primary host plant, blue grama, and a favorable place in
which to live and reproduce.
Courtship appears to be similar to that of C. occipitalis. A
male moves close to a female, tips his hindlegs, depresses his antennae,
and then produces a single burst of stridulation. He then tips his hindlegs
forward and advances towards the female. The act of mounting and initial
copulation has not been observed. A field observation was made of a pair
in copulation at 11:20 a.m. DST 27 July 1973 in the usual manner of grasshoppers
with the male atop the female.
One observation of oviposition from start to finish was made in the
mixedgrass prairie of eastern Wyoming on 22 August 1991. A gravid female
selected an old crown of blue grama grass in which to oviposit. She braced
herself with the forelegs and midlegs on an adjacent blue grama plant and
held the hindlegs off the ground. Oriented diagonally at a 45° angle
she started boring into the soil at 10:53 a.m. DST (soil surface was 105°F,
air temperature 1 inch above ground was 82°F, clear, wind 0-5 mph).
An attending male stridulated briefly at the beginning of oviposition,
but otherwise stood quietly one-quarter inch from her pronotum. She completed
oviposition and withdrew her abdomen after 26 minutes (soil surface was
112°F, air temperature 1 inch above ground was 89°F, clear, wind
0-5 mph). For one minute she brushed soil and litter over the hole with
her hind tarsi, but the opening remained visible. Afterwards, she climbed
on top of a blue grama plant and rested, while the attending male walked
away. Three eggs, lightly cemented together and vertically oriented, were
recovered from the soil cell. Another observation of oviposition was made
26 July 1978 between 8:30 and 9:00 a.m. (air temperature at 8:30 was 72°F);
this female also bored into an old blue grama crown.
Crenulatewinged females produce two to three eggs at one time, but do
not produce a pod for their protection. The eggs are pale yellow and 5
to 5.5 mm long (Fig. 8).
The crenulatewinged grasshopper is a resident of western grasslands, and
lives most often as a subdominant member of an assemblage of 12 to 18 acridid
species. Densities usually remain low, ranging from 0.05 to 1 young adult
per square yard. In many areas of the mixedgrass, shortgrass, and desert
prairies it does not appear to be present as measured by square foot visual
sampling or by sweep net collection. On sites where it is present, populations
persist from year to year in fluctuating low numbers (Table
1). The environmental factors that allow increases in typically dominant
species also allow increases in the crenulatewinged grasshopper. How increases
arise in the latter species to dominance of eight per square yard is unknown.
The crenulatewinged grasshopper spends the night resting in the crown of
blue grama grass or on ground litter under a canopy of blue grama. At sunrise
the grasshoppers are immobile and quiet. At this time, ground surface and
air temperatures are low, ranging from 50° to 60°F. About 90 minutes
later, the grasshoppers begin to stir and take basking positions in which
they assume two main orientations. Sitting on top of blue grama or on ground
litter they may present a side perpendicular to the sun's rays and lower
the exposed hindleg. In this orientation, some grasshoppers tilt their
bodies slightly to expose their backs as well as their sides. In the second
orientation, grasshoppers rest diagonally on blue grama with their hindlegs
on the ground so as to expose their backs to the sun's rays. Grasshoppers
bask for about one to two hours before they begin normal activities of
pottering, feeding, mating, and ovipositing. These activities continue
until temperatures become too hot (surface of soil 120°F and air temperature
1 inch above ground 85°F). The grasshoppers then either climb grass
leaves and rest head up one-fourth to one inch above ground level or they
climb on top of blue grama and face the sun to expose a minimum of their
body surface. In the latter orientation, they may spread apart their flexed
hindlegs. When temperatures moderate they again become active. Only one
observation has been made of this grasshopper as it settled down for the
night. Shortly before sunset, a female was discovered sitting quietly on
the ground under a canopy of blue grama plants.
Anderson, N. L. and J. C. Wright. 1952. Grasshopper investigations on Montana
range lands. Montana Agr. Exp. Stn. Bull. 486.
Fry, B., A. Joern, and P.L. Parker. 1978. Grasshopper food web analysis:
use of carbon isotope ratios to examine feeding relationships among terrestrial
herbivores. Ecology 59: 498-506.
Joern, A. 1983. Small-scale displacements of grasshoppers (Orthoptera:
Acrididae) within arid grasslands. J. Kansas Entomol. Soc. 56: 131-139.
Otte, D. 1970. A comparative study of communicative behavior in grasshoppers.
Univ. Michigan Mus. Zool. Misc. Publ. 141.
Pfadt, R. E. 1982. Density and diversity of grasshoppers (Orthoptera:
Acrididae) in an outbreak on Arizona rangeland. Environ. Entomol. 11: 690-694.
Pfadt, R. E. and R. J. Lavigne. 1982. Food habits of grasshoppers inhabiting
the Pawnee site. Wyoming Agr. Exp. Stn. Sci. Monogr. 42.
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