Striped Slant-faced Grasshopper - Amphitornus coloradus
The following comes from Hebard (1928), Brooks (1958), Helfer (1971), Otte (1981), Capinera and Sechrist (1982), Vickery and Kevan (1985), McDaniel (1987), Pfadt (2002), Capinera et al. (2004), and Scott (2010). Medium-sized, brownish-yellow or green grasshopper. Two dark brown stripes run from the top of the head and broadening across the pronotum and fading onto the wings (tegmina). The hind tibia is blue. The face is strongly slanted, and the antennae are flattened.
Overwinters in the egg stage. Eggs hatch at the end of May or early June. Adults occur from late-June to early-October (Capinera et al. 2004, Capinera and Sechrist 1982, Otte 1984, Pfadt 2002, Schell et al. 2005, Scott 2010, and Vickery and Kevan 1985).
The following is taken from Hebard (1928), Brooks (1958), Helfer (1971), Otte (1981), Capinera and Sechrist (1982), Vickery and Kevan (1985), McDaniel (1987), Pfadt (2002), Capinera et al. (2004), and Scott (2010). Adult body length for males is 18 to 20 mm, and females 21 to 25 mm. Hind femur has three dark bands on the upper outer surface. Junction of femur knee with the tibia is black. Wings (tegmina) are unspotted with a white stripe on the lower basal third.
Could be confused with similarly marked slantfaced species in the genera Cordillacris, Opeia, Mermiria, or Psuedopomala. Closely observe diagnostic characteristics for positive identification.
Widely distributed across the grasslands of North America, from the western provinces of Canada, southward into central Mexico, and westward from western Illinois to Washington, Oregon, and California. In Montana, this species has been recorded for 49 counties, but likely occurs in suitable grassland habitats throughout the state (Brooks 1958, Capinera et al. 2004, Capinera and Sechrist 1982, Otte 1984, Pfadt 2002, Schell et al. 2005, Scott 2010, and Vickery and Kevan 1985).
Observations in Montana Natural Heritage Program Database
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Prefers mixed-grass and bunchgrass prairies. Also inhabits dry, grassy slopes and small, grassy spots along river valleys. Often clings to grasses and never seen walking over open ground. Usually occurs at elevations below 7600 feet, but accidentals have been collected as high as 11,400 feet (Capinera et al. 2004, Capinera and Sechrist 1982, Otte 1984, Pfadt 2002).
The Striped Slant-faced feed almost exclusively on grasses and sedges, favoring blue gramma
), thread-leaved sedge
) and needleleaf sedge
). Seventeen other grass species have been reported consumed, as well as some forbs (Capinera and Sechrist 1982, Pfadt 2002, Schell et al. 2005).
Males stridulate before making a copulatory leap on the female. The female selects a needle-and-thread
) or a thread-leaved sedge
) in which to oviposit her eggs. She deposits four eggs on the plant stem and forms a pod just below the soil surface. The outer wall of the pod is constructed of dry fragments of grass and soil particles. The nymphs pass through 5 instars before reaching the adult stage in 50 to 56 days (Capinera and Sechrist 1982, Pfadt 2002, Schell et al. 2005).
The Striped Slant-faced Grasshopper can cause damage to rangelands and native grasslands. Among the assemblages of grasshoppers infesting rangelands, it is rarely the dominate species but can be the third most abundant (Pfadt 2002, Schell et al. 2005).
- Literature Cited AboveLegend: View Online Publication
- Brooks, A.R. 1958. Acridoidea of Southern Alberta, Saskatchewan, and Manitoba (Orthoptera). The Canadian Entomologist (Supplement 9) 90:5-92.
- Capinera, J.L. and T.S. Sechrist. 1982. Grasshoppers of Colorado: Identification, Biology, and Management. Fort Collins, CO: Colorado State University Experiment Station, Bulletin 584S. 161 p.
- Capinera, J.L., R.D. Scott, and T.J. Walker. 2004. Field Guide to Grasshoppers, Katydids, and Crickets of the United States. Ithaca, NY. Cornell University Press.
- Hebard, M. 1928. The Orthoptera of Montana. Proceedings of the Academy of Natural Sciences of Philadelphia, Vol. 80:211-306.
- Helfer, J.R. 1971. How to Know the Grasshoppers, Crickets, Cockroaches, and Their Allies. Revised edition (out of print), Mineola, NY: Dover Publications.
- McDaniel, B. 1987. Grasshoppers of South Dakota. Brookings, SD: South Dakota Agricultural Experiment Station, Bulletin TB 89.
- Otte, Daniel. 1981. The North American Grasshoppers. Volume 1. Acrididae (Gomphocerinae and Acridinae). Harvard University Press. 275 pp.
- Pfadt, R.E. 2002. Field Guide to Common Western Grasshoppers, 3rd edition. Laramie, WY: Wyoming Agricultural Experiment Station, Bulletin 912, modified by S. Schell and S. Schell for electronic publication. Accessed 19 February 2020. http://www.uwyo.edu/entomology/grasshoppers/field-guide/index.html#fieldguidetoc
- Schell, S.P., A.V. Latchininsky, and B.A. Shambaugh. 2005. Common Wyoming Pest Grasshoppers. 2nd Edition B-1161.Laramie, WY: University of Wyoming Cooperative Extension Service and Department of Renewable Resources. 76 p.
- Scott, R.D. 2010. Montana Grasshoppers, Katydids, and Crickets A Pictorial Field Guide to the Orthoptera. MagpieMTGraphics, Billings, MT.
- Vickery, V. R. and D. K. M. Kevan. 1985. The grasshopper, crickets, and related insects of Canada and adjacent regions. Biosystematics Research Institute, Ottawa, Ontario. Publication Number 1777. 918 pp.
- Additional ReferencesLegend: View Online Publication
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- Anderson, N.L. 1951. Field studies on the biology of range grasshoppers of southeastern Montana. M.Sc. Thesis. Bozeman, Montana: Montana State University. 96 p.
- Anderson, N.L. 1962. Grasshopper-vegetation relationships on Montana grasslands. Ph.D Dissertation. Bozeman, Montana: Montana State University. 73 p.
- Gillespie, R.L.1992. Dynamics of grasshoppers (Orthoptera: Acrididae) at a rangeland-crop interference. Ph.D. Bozeman, MT: Montana State University. 111 p.
- Hebard, M. 1932. Notes on Montana Orthoptera. Proceedings of the Academy of Natural Sciences of Philadelphia. V. 84. pp 251-257.
- Larson, D.P. 1996. Evaluation of sweep sampling as a method for determining grasshopper community composition on rangeland. M.Sc. Thesis. Bozeman, MT: Montana State University. 92 p.
- Mussgnug, G.L. 1972. The structure and performance of an adult population of Aulocara elliotti (Thomas) (Orthoptera, Acrididae) near Billings, Montana. M.Sc. Thesis. Bozeman, MT: Montana State University. 97 p.
- Skinner, K.F. 1995. Plant and grasshopper community composition: indicators & interactions across three spatial scales. M.Sc. Thesis. Bozeman, MT: Montana State University. 144 p.
- Wachter, D.H. 1995. The ecology of selected grasshopper species along an elevational gradient. M.Sc. Thesis. Bozeman, Montana: Montana State University. 59 p.
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