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Montana Field Guides

Assiniboine Skipper - Hesperia assiniboia

Global Rank: G5
State Rank: S5

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General Description
Not all authorities have agreed on the taxonomic status of members in the Hesperia comma group, which includes H. assiniboia (Scott 1975d, 1986; Scott and Fisher 1998; Layberry et al. 1998; Oppler and Wright 1999; Guppy and Shepard 2001; Forister et al. 2004; Alcorn and Sheldon 2006). Some treat H. assiniboia as a subspecies of H. comma, others consider it a subspecies of H. colorado, and others treat it as a full species, currently the accepted status. Given past taxonomic uncertainty and instability, this account probably includes information pertaining to more than one species.

[From Ferris and Brown 1981; Scott 1986; Layberry et al. 1998; Opler and Wright 1999; Glassberg 2001] Forewing 1.3-1.6 cm. Antennae relatively long, wing fringes long, white or pale. Uppersurface appears dark, with reduced tawny areas. Male stigma (scent patch) with black interior "felt." Undersurface of hindwing pale green or gray-green, postmedian chevron broken into 2-3 groups of pale-yellow spots (sometimes whitish, often small, sometimes absent).

One flight, mainly late June to early August in Saskatchewan (Scott 1986). Late June to early September (Layberry et al. 1998; Opler and Wright 1999; Glassberg 2001). Mid-June to late September in North Dakota (McCabe and Post 1976), late July to late August in British Columbia (Guppy and Shepard 2001).

Diagnostic Characteristics
Best determined by a combination of the male stigma (bulb at antenna tip) with black interior "felt", undersurface of hindwing pale green or gray-green (not darker), postmedian chevron broken into 2-3 groups of pale-yellow spots (sometimes whitish, often small, sometimes absent), the chevron band not continuous.

Species Range
Montana Range

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Range Comments
West-central British Columbia east to central and southeastern Manitoba, south to southern Montana, North Dakota, northeastern South Dakota (Layberry et al. 1998; Opler and Wright 1999; Glassberg 2001; Guppy and Shepard 2001). In Montana, reported from at least 17 counties in the eastern prairie region, as far west as Pondera County in the north, Sweet Grass county in the south (Kohler 1980; Standford and Opler 1993; FLMNH Lepidopterists' Society database), to at least 1650 m elevation. Mainly common to abundant (Glassberg 2001).

Non-migratory. Most probably move 100 m or less in suitable habitat (James and Nunnallee 2011).

Short-grass prairie, aspen parkland (Scott 1986; Layberry et al. 1998; Opler and Wright 1999; Glassberg 2001). Habitat in Montana not described but probably similar.

Food Habits
Larval food plants are grasses, including Bouteloua, Hesperostipa (=Stipa), and Koeleria, possibly Carex and other grass species such as Andropogon and Bromus (Scott 1986, 1992, 2006; Layberry et al. 1998). Adults feed on flower nectar (including Achillea, Arctium, Berteroa, Campanula, Carduus, Centaurea, Chrysothamnus, Cichorium, Cirsium, Dipsacus, Erigeron, Eriogonum, Geranium, Grindelia, Gutierrezia, Helianthus, Heterotheca, Liatris, Machaeranthera, Medicago, Penstemon, Rudbeckia, Senecio, Solidago, Symphyotrichum, Viguiera) and mud (Scott 2014).

Reproductive Characteristics
Limited information. Females lay eggs somewhat haphazardly on or near host plant mostly on underside of leaf. Eggs diapause (overwinter), with L1 instar well developed. Larval development to pupation may take up to 129 days in captivity, with possibly 6 instars. Larvae feed on host plant leaves, live in nests of rolled and silk-tied leaves, pupate in silken cocoon within leaf nest, adults eclose (emerge from pupae) in about 19-30 days (Scott 1975e, 1979, 1986, 1992, 2006; James and Nunnallee 2011). Males probably perch throughout the day on flats and hilltops near host plants, waiting for passing females (Scott 1975b, 1986; James and Nunnallee 2011).

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Assiniboine Skipper — Hesperia assiniboia.  Montana Field Guide.  .  Retrieved on , from