Montana Field Guide

[From Ferris and Brown 1981; Scott 1986; Layberry et al. 1998; Opler and Wright 1999; Glassberg 2001] Forewing 1.5-1.8 cm. Uppersurface pale tawny-orange, male stigma on forewing relatively long with yellow interior felt; female with extensive black strongly contrasting pale yellow spots. Undersurface pale yellow-orange, hindwing with postmedian chevron reduced to a few small cream to whitish spots or completely absent.

One flight, mid-August to early September northward, late August to mid-September southward, mid-September to early October in Arkansas (Scott and Stanford 1981; Scott 1986). Mid-August through September (Glassberg 2001). August and September in Canada (Layberry et al. 1998). Mid-August through September in the Rocky Mountain states (Ferris and Brown 1981). Mid-August to mid-September in Colorado (Scott and Scott 1978; Scott and Stanford 1981; Wooley et al. 1991), late August to early September in Nebraska (Dankert and Nagel 1988), early August to early October in North Dakota (McCabe and Post 1976).

Best determined by a combination of late flight season, male stigma on uppersurface of forewing relatively long with yellow interior felt, female uppersurface with extensive black strongly contrasting pale yellow spots, undersurface of hindwing with postmedian chevron reduced to a few small cream to whitish spots or completely absent.

Non-migratory.

Short-grass prairie, grassy openings in ponderosa pine woodland (Ferris and Brown 1981; Scott 1986; Dankert and Nagel 1988; Layberry et al. 1998; Opler and Wright 1999; Glassberg 2001), dry and sandy prairie and barrens in upper Midwest, in sites experiencing some grazing and haying (Reed 1997; Swengel and Swengel 1999, 2015). Habitat in Montana not described but probably similar.

Larval food plants are grasses, including Agrostis, Andropogon, Bouteloua (several species), Bromus, Danthonia, Eragrostis, Panicum, Poa, Sporobolus, Stipa, and Tridens; also Cynodon in captivity, sometimes sedges (Carex) (Ferris and Brown 1981; Scott and Stanford 1981; Scott 1986, 1992, 2006; Wooley et al. 1991; Layberry et al. 1998). Adults feed on flower nectar (including Allium, Carduus, Chrysopsis, Chrysothamnus, Cirsium, Clematis, Dalea, Echium, Erigeron, Eriogonum, Eupatorium, Geranium, Grindelia, Gutierrezia, Helianthus, Heliomeris, Heterotheca, Liatris, Lycium, Machaeranthera, Monarda, Petalostemum, Ratibida, Senecio, Solidago, Symphyotrichum, Tagetes, Verbesina, Veronia) and mud (Scott and Stanford 1981; Wooley et al. 1991; Layberry et al. 1998; Swengel and Swengel 1999; Scott 2014).

Limited information. Females lay eggs singly and haphazardly on and near host plant on undersides of leaves. Eggs hatch in fall, larvae live in silk-tied leaf nest, L1 instar (rarely L2 instar) overwinters, continues feeding on host plant leaves the following spring until pupation (83-114 days post egg-hatch in captivity), adults eclose (emerge from pupae) in captivity in 19-36 days, depending on temperature (Scott 1975e, 1979, 1986, 1992). Males patrol throughout the day, sometimes perch, on hilltops near favored nectaring flowers (especialy Liatris) searching or waiting for passing females (Scott 1975b, 1982, 1986; Ferris and Brown 1981; Scott and Stanford 1981).