Wyoming distribution map
The redshanked grasshopper ranges widely in western North America, inhabiting the grasslands and shrub-grass communities. The species is also present in clearings of montane forests and in open vegetated areas above timberline.
The redshanked grasshopper is a large species. Live weights of males from mixedgrass prairie average 607 mg and of females 1,352 mg (dry weight: males 117 mg, females 442 mg).
A total of 22 species of grasses, two species of sedges, and one rush have been found in crop contents of the redshanked grasshopper. Because of its wide distribution in diverse habitats, known host plants are undoubtedly far short of the actual numbers eaten. Trace quantities of forbs (29 species), fungi, and arthropod parts have been found in crop contents. An apparent exception is the large quantity (17 percent dry weight) of the forb, woolly plantain, found in the crops of ten adults in July on the shortgrass prairie of northeastern Colorado.
Observation of the feeding of one adult female in the mixedgrass prairie of eastern Wyoming suggests that this grasshopper feeds on the ground in a horizontal position. The female fed on four western wheatgrass plants from 10:53 to 11:03 a.m. DST. Crawling and foraging on the ground, she raised her head upon contacting a host plant and cut a leaf an inch above ground level, then fed on the felled leaf from the cut end to the tip. She handled the leaf with her front tarsi from a horizontal position on the ground. Laboratory observations were made of late instar nymphs feeding from a horizontal ground position on dry fallen leaves of downy brome while housed in a gallon cage with soil as the floor. These observations indicate that the redshanked grasshopper may feed on ground litter as well as on green leaves that they cut.
Little information is available on its dispersal and possible migration. Populations in habitats at different altitudes west of Boulder, Colorado did not disperse into nonresident habitats. In the recent outbreak in Utah, however, adults were observed to fly from denuded grass habitats to nearby alfalfa fields.
The pronotum is heavily nodulate and rugose; the median carina is low and cut twice in front of the middle. The hind femur has three diagonal dark brown bands on its outer face and a solid bright red or deep blue inner face. The hind tibia is either entirely red or is yellow on the outer face and red on the inner face.
The nymphs are identifiable by their shape, structures, and color patterns (Fig. 1-6).
1. Head rounded with face nearly vertical; lateral foveolae triangular; vertex with integument wrinkled except smooth in instar I. Maxillary and labial palps with segments pale gray and proximal ends ringed black, terminal segment with an additional black ring near tip; rings fading in instars IV to VI.
2. Pronotum with integument smooth in instar I, nodulate and wrinkled instars II to VI; median carina of disk low but equally elevated throughout, entire in instar I, cut twice in instars II to VI, principal sulcus deeply cut, front sulcus often faintly cut; lateral carinae of disk pale yellow; a light V-shaped figure on anterior half of disk; light lateral lines on posterior half extend to arms of V (see Figure 2 for side view).
3. Hind femur with lower carina expanded into a conspicuous keel (instars III to VI); outer face tan with three diagonal brown bands, inner face dark blue with pale yellow band next to knee, sometimes a smaller second band near middle, orange or red interfusions on inner face in instars V and VI. Hind tibia shiny dark blue to black in instars I and II, orange or dark blue with orange patches in instars III to VI.
4. Body color brown or gray with many dark brown spots; individuals developing on red soils become red and lose color patterns and majority of markings in instars III to VI (see Figure 4).
In southern populations eggs of the redshanked grasshopper hatch in mid-summer, two to four weeks after the hatching of the brownspotted grasshopper, Psoloessa delicatula, and the specklewinged grasshopper, Arphia conspersa. In the mixedgrass prairie of western North Dakota at altitudes of 2,000 feet, hatching of the redshanked grasshopper begins in mid-July; in the shortgrass prairie of northeastern Colorado at altitudes of approximately 5,400 feet, hatching begins the last week of July; while in the mixedgrass prairie of eastern Wyoming at altitudes of 4,400 feet to 5,300 feet, hatching begins in mid-August. The period of hatching lasts approximately four weeks.
Although the act of oviposition in the natural habitat has gone undescribed, circumstantial evidence indicates the female selects bare ground for this purpose. In a laboratory terrarium transplanted with vegetation from the mixedgrass prairie, females chose to oviposit in bare soil. Over one hour was required to complete an oviposition. After extracting her abdomen, a female takes a minute to brush soil over the hole with her hind tarsi. Females deposit eggs deeply in the soil; eggs lie at a depth of 2 to 3 inches.
The egg pod is two and three-quarters inches long and slightly curved (Fig. 10). The diameter of three-eighths inch in the bottom region containing the eggs is greater than in the top region of froth. Eggs are brown and 6 to 6.5 mm long and number about 32 per pod.
Like the nymphs, adults appear to rest horizontally on the soil surface at night. Adults have been flushed from the ground surface and may jump to evade capture in the morning (8:30 a.m. DST) when ground surface temperature is 60°F. Later (9:30 a.m.), at soil surface temperature of 76°F, flushed adults fly evasively from the ground. One observation was made of a female basking late in the morning (10:45 a.m., soil temperature 80°F) with her left side perpendicular to the sun's rays. This same female began to feed at 10:55 a.m.
When temperatures rise above tolerable levels, greater than approximately 130°F at the soil surface, females have been observed to move across the ground to the shady side of shrubs and males have been observed to climb plants, such as western wheatgrass, to 3 to 6 inches above the soil surface and then rest on the shady side of the plant.
Frase, B. A. and R. B. Willey. 1981. Slowed motion analysis of stridulation in the grasshopper, Xanthippus corallipes (Acrididae: Oedipodinae). Can. J. Zool. 59: 1005-1013.
Onsager, J. A. and G. B. Mulkern. 1963. Identification of eggs and egg-pods of North Dakota grasshoppers (Orthoptera: Acrididae). North Dakota Agr. Exp. Stn. Bull. 446 (Technical).
Otte, D. 1984. The North American Grasshoppers, Vol. II Acrididae, Oedipodinae. (Harvard University Press: Cambridge, Massachusetts).
Pfadt, R. E. and R. J. Lavigne. 1982. Food habits of grasshoppers inhabiting the Pawnee Site. Wyoming Agr. Exp. Stn. Sci. Monogr. 42.
Pickford. R. 1953. A two-year life-cycle in grasshoppers (Orthoptera: Acrididae) overwintering as eggs and nymphs. Can. Entomol. 85: 9-14.
Ueckert, D. N. and R. M. Hansen. 1971. Dietary overlap of grasshoppers on sandhill rangeland in northeastern Colorado. Oecologia 8: 276-295.
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