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The Carolina grasshopper, a large bandwinged species, ranges widely in North America inhabiting weedy grasslands. Blowouts, field margins, roadside strips, weedy fence rows, railway cuttings, and disturbed rangeland support moderate populations of this species. During the day when temperatures warm, the adults move from vegetated to bare areas such as dirt roads where they fly about and become highly conspicuous.
Because of its large size the Carolina grasshopper has been regarded as a voracious feeder capable of causing much damage at moderate densities. The live weight of males averages 570 mg and of females 1,467 mg (dry weight: males 171 mg, females 387 mg).
Two-choice laboratory tests revealed that the Carolina grasshopper fed readily on downy brome, smooth brome, western wheatgrass, wheat, barley, dandelion, and kochia. Because of its wide distribution, the Carolina grasshopper undoubtedly has many more host plants than presently known.
Several observations of the Carolina grasshopper's feeding in nature have been made. On 5 August 1992 at 6:51 p.m. DST with soil temperature 81°F and air at 1-inch level 74°F, an instar III female climbed a 3-inch tall kochia plant and in a vertical head-up position fed on a kochia leaf (2 x 7 mm) beginning at the tip and devouring it to its base leaving a 2 mm stub.
On 27 July 1990 at 9:10 a.m. an adult male was discovered sitting on ground litter facing the sun in a city lot. At 9:13 a.m. the male began to stir and walked a short distance to a short grass, Buchloe dactyloides. At 9:14 a.m. the male reached up with its mouthparts to the tip of a leaf and consumed the whole leaf to the base. He then attacked another leaf of the same plant, cutting it near the middle. Holding onto the cut section with the front tarsi, he consumed all of it from the cut end to the tip. He then cut another leaf of the same plant near the base, held onto it with the front tarsi, and ate all of it. A fourth and final leaf was eaten from the tip to the base. Feeding ended at 9:24 a.m. During all of the feeding the male sat horizontally on the ground, resting on the mid- and hindlegs and using the forelegs to handle the food. The weather was clear, warm, and calm (soil surface 94°F, air 72°F, at 1-inch level, wind 0-2 mph).
On 2 October 1992 from 4:28 to 4:37 p.m. DST (soil surface 92°F and air 1-inch level 80°F), three females wandering around on bare ground were observed to feed on ground litter (dry grass and unidentifiable vegetation). The females were horizontal on the surface. One female was observed to spread out her front legs rather than use the front tarsi to handle the food.
These few observations suggest that the Carolina grasshopper is a thrifty feeder because it appears to eat all of whatever it attacks.
In voluntary or appetitive flights, adults fly a distance of 2 to 36 feet at heights of usually 1 to 2 feet. They undulate and may crepitate as they fly. Adults are wary and flush readily at the approach of a person. In flushed flight they may travel a distance of 4 to 70 feet or much farther in a strong wind. They fly at heights of 1 to 5 feet and often make a right angle turn at variable distances into the flight before landing on the ground.
No special study of dispersal or migratory flight has been made, but it is known that adults have moved from resident localities near Boulder, Colorado to nonresident mountain sites above 10,000 feet, approximately 14 miles west. In the vicinity of Washington, D.C., considerable numbers frequently fly around the electric lights during warm summer nights. The species has also been collected at lights in Presidio, Texas and in North Branch and Minneapolis, Minnesota.
The nymphs are identifiable by their color patterns, shape, and external structures (Fig. 1-5).
1. Head with face nearly vertical; antennae filiform, terminal segments dark, basal segments colored like body; lateral foveolae small and triangular.
2. Pronotum with median carina strongly elevated and cut once.
3. Hind femur with medial area evenly colored like body, may be spotted in instars IV and V; inner knee tan or fuscous, basal half of inner medial and lower marginal areas fuscous, distal half with two pale yellow transverse bands (Fig. 9); hind tibia of instar I and II black with basal annulus pale yellow, hind tibia of instars III to V with variable patterns of tan, gray, and black; hind tarsus white or pale yellow except distal end fuscous.
4. General body color tan, brown, or gray. Reddish in individuals developing on red soils.
The habitat in which the eggs hatched and the nymphs developed remains occupied by adults, most likely by an assemblage composed of some of the original inhabitants and some immigrants. The males court females by producing a calling signal using their hindlegs and wings to stridulate. One hindleg at a time is rubbed against the tegmen in a behavior called alternate stridulation. A male sits horizontally on bare ground in sunlight and may continue to call for 5 minutes or longer until he attracts a female. She walks toward him and when she is close he approaches her and mounts. If he is successful, the pair mate. They may remain in copulo for as long as 16 hours.
Sexual maturation of females appears to be prolonged. In Minnesota, where the adult stage is reached in early June, the females do not begin to oviposit until early August, suggesting that nine weeks are required for maturation. In Manitoba, oviposition has been observed in September and in Wyoming in September and October.
The female selects compact bare ground exposed to the sun in which to oviposit. The selected site is often the edge of a gravel or dirt road. She works her ovipositor to a depth of 1 1/2 inches and deposits a large clutch of eggs that she encloses in a sharply curved pod (Fig. 10). After approximately 1 1/3 hours, she extracts her ovipositor and for one to three minutes brushes surface particles with her hind tarsi over the aperture of the hole. The pod, nearly 2 inches long, usually contains more than 40 eggs. Two egg pods obtained after observing the females oviposit at the edge of a gravel road in southeastern Wyoming contained 50 and 57 eggs, respectively. Reared in a greenhouse, caged females have laid from 30 to as many as 70 eggs in a pod. The eggs are reddish brown and 4.8 to 5.8 mm long.
Although adults are conspicuous because of their size and flashy wings, giving the impression of large numbers, the density of populations is usually low, around 0.1 to 0.2 young adults per square yard. Populations irrupt infrequently, as in southern Saskatchewan in 1933 and 1934, causing serious loss of crops. No estimates of absolute densities were determined during this outbreak.
After basking, the adults begin to walk and fly about the habitat. The males are more active than the females, perhaps searching for receptive females with which to mate. Females walk and fly far less than males, but do more feeding, grooming, and resting. Seven observations of feeding by adults indicate that this activity occurs in the afternoon from approximately noon to 5 p.m. DST. An observation of courting occurred at 12:25 p.m. Mating pairs have been observed in the afternoon: two pairs at 2:15 p.m., one pair at 3:15 p.m., and one pair at 3:47 p.m. In the George Reserve, Michigan, a pair observed in copulo at 5:20 p.m. on August 4, remained together until 7:50 a.m. the next morning. Three extended observations of oviposition in eastern Wyoming indicate that females perform this function during midday with oviposition beginning as early as 10:30 a.m. and as late as 2:30 p.m.
Hot ground temperatures of 110°F. and air temperature of 90°F., 1-inch level, induce the adults to stilt. As temperatures rise, the grasshoppers climb on vegetation and place themselves 1-3 inches above ground. They face the sun directly so that only the front of the head is exposed to the rays and the rest of the body is shaded.
In the afternoon the adults bask on bare ground for a second time beginning about 3 p.m. and ending about 5 p.m. Then they walk or fly to vegetated areas where they seek shelter usually under canopies of grasses. Sampling of their density on a bare, gravel road in Laramie County, Wyoming on 4 October 1992 showed that adults (0.06 per square yard) were 20 times more prevalent at 4 p.m. DST than at 5:17 p.m., and none were found at 5:29 p.m.
Kerr, G.E. 1974. Visual and acoustical communicative behaviour in Dissosteira carolina (Orthoptera: Acrididae). Can. Entomol. 106: 263-272.
Kerr, G.E. 1978. Uncertainty analyses of the behaviour of the Carolina locust, Dissosteira carolina (Orthoptera: Acrididae). Can. J. Zool. 56: 201-214.
Otte, D. 1970. A comparative study of communicative behavior in grasshoppers. Misc. Publ. Mus. Zool. Univ. Michigan, No. 141.
Riegert, P.W. 1968. A history of grasshopper abundance surveys and forecasts of outbreaks in Saskatchewan. Memoirs Entomol. Soc. Can. No. 52.
Scoggan, A.C. and M.A. Brusven. 1972. Differentiation and ecology of common immature Gomphocerinae and Oedipodinae (Orthoptera: Acrididae) of Idaho and adjacent areas. Melanderia Vol. 8.
Somes, M.P. 1914. The Acrididae of Minnesota. Minnesota Agr. Exp. Stn. Bull. 141.