Oarisma garita (Reakirt, 1866)
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Basis for Listing
The Garita Skipperling, also known as the Garita Skipper, is a grassland species ranging from northern Mexico north through the Great Plains and Rocky Mountains to the Canadian parklands (Layberry et al. 1998; Opler et al. 2006). It reaches its eastern limit in southern Manitoba and northwestern Minnesota (although there is a disjunct population near Mantoulin Island in Ontario). Breeding colonies of the Garita Skipperling were discovered in the aspen parkland in Kittson County in the late 1980s (R. Dana, Minnesota DNR, pers. comm.), where colonies have been confirmed at three sites (Cuthrell 1991). There is also a record from the late 1960s from Clay County that may represent a brief, adventive establishment. All locations in Kittson County are in native prairie or savanna habitat on sandy soils. This habitat was always a minor landscape component in the region, and conversion of lands to crop production, overgrazing, aggregate mining, and succession to woodland have further reduced the amount.
The Garita Skipperling is a small butterfly, smaller and more delicate looking than most other skippers in Minnesota. Forewing length (base to apex) is 1.1-1.3 cm (0.4-0.5 in.) in both sexes. Antennae are short and relatively stout and have blunt-tipped clubs. Though capable of rapid flight, this skipperling more typically flies erratically just above the grass tops at a speed that is relatively easy to follow with the eye. Its flight is somewhat mothlike and lacks the skipping quality that gives the family its name.
Habitat for the Garita Skipperling in Manitoba is described as dry and moist virgin prairie, with hollows or bases of hills favored in dry prairie (Klassen et al. 1989). Dry prairie seems to be the preferred habitat in North Dakota, where the Poweshiek Skipperling occupies moister prairie (McCabe and Post 1977). In Minnesota, the Garita Skipperling has been observed in prairie openings on sandy soils, in either old dune formations or outwash deposits. In all cases, moister swales or hollows occur together with the drier hillocks or swells. Dominant grasses of the drier prairie include little bluestem (Schizachyrium scoparium var. scoparium), prairie junegrass (Koeleria macrantha), porcupine grass (Hesperostipa spartea), and needle-and-thread grass (S. comata). In one of these locations there are scattered small, gnarly bur oaks (Quercus macrocarpa).
Biology / Life History
The Garita Skipperling has a single annual generation. All observations of this species in Minnesota have been in the first half of June, although the flight period probably extends somewhat into July, as it does in North Dakota and Manitoba (McCabe and Post 1977; Royer 1988; Klassen et al. 1989). It overwinters as a partly grown larva and completes development the following spring (Scott 1986).
Conservation / Management
Small colony sizes due to past habitat loss, and further habitat destruction are the primary threats facing the garita skipper in Minnesota. All habitat that is not protected by permanent dedication for conservation is at risk of destruction for agricultural production, aggregate mining, or development. Loss of the unprotected habitat at the sites where this skipperling is known to occur will make the colonies even more vulnerable. Extirpation could result from natural events (such as severe drought or hailstorms) or human caused ones (such as insecticide application), as well as from the vagaries of normal population processes (for example, by chance all adults in one generation are males). Loss of genetic diversity is another possible threat. Even where protected, the habitat in northwestern Minnesota is strongly susceptible to woodland invasion and requires active management intervention to maintain it.
Conservation Efforts in Minnesota
Following the discovery of breeding colonies of the Garita Skipperling in Kittson County, the Minnesota DNR conducted a more intensive survey in the Tallgrass Aspen Parklands Province of northwestern Minnesota. All three locations found are substantially protected from destructive development: a Minnesota DNR Wildlife Management Areas, a State Park, and a Nature Conservancy preserve. No conservation efforts specifically targeted to this skipperling have been undertaken; however, prescribed burning at the Nature Conservacy site is conducted in accordance with guidelines that reduce risk to grassland insects. The other two sites have enough habitat that prescribed burning is not likely to extirpate the skipperling colonies. Additional survey work on this species is needed.
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Cuthrell, D. L. 1991. The butterflies of Kittson and Roseau counties, Minnesota, with special emphasis on the Dakota Skipper (Hesperia dacotae) [Skinner]. Final report submitted to the Nongame Wildlife Program, Minnesota Department of Natural Resources. 48 pp.
Klassen, P., A. R. Westwood, W. B. Preston, and W. B. McKillop. 1989. The butterflies of Manitoba. Manitoba Museum of Man and Nature, Winnipeg, Manitoba. 290 pp.
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McCabe, T. L., and R. L. Post. 1977. Skippers (Hesperioidea) of North Dakota. North Dakota Insects Publication No. 11, Schafer-Post Series. Agricultural Experiment Station, University of North Dakota, Fargo, North Dakota. 70 pp.
Opler, P. A., H. Pavulaan, R. E. Stanford, and M. Pogue, coordinators. 2006. Butterflies and moths of North America: Garita Skipperling (Oarisma garita). Bozeman, Montana: NBII Mountain Prairie Information Node.
Royer, R. A. 1988. Butterflies of North Dakota: an atlas and guide. Science Monograph Number 1, Minot State University, Minot, North Dakota. 192 pp.
Scott, J. A. 1986. The butterflies of North America: a natural history and field guide. Stanford University Press, Stanford, California. 583 pp.
Swengel, A. B. 1998. Effects of management on butterfly abundance in tallgrass prairie and pine barrens. Biological Conservation 83(1):77-89.