Montana Field Guide

[From Ferris and Brown 1981; Scott 1986; Layberry et al. 1998; Opler and Wright 1999; Glassberg 2001; Pyle 2002] Forewing 1.1-1.2 cm. Uppersurface dark brown with restricted yellow patches and yellow apical spots, male forewing with gray-brown patch below sinuous black stigma extending almost to darker border, stigma with yellow interior felt; undersurface of hindwing chestnut-brown with a broad postmedian patch of yellow spots surrounded by darker border, the central yellow spot jutting outward, a second smaller yellow patch near hindwing base.

One flight, mostly July in the north and at higher elevation; two flights, late May to mid-June and late July to mid-September elsewhere (Scott 1986). Mid-June to early August in one-brood areas, May to September in two-brood areas (Glassberg 2001). Late June to early August in Canada (Layberry et al. 1998). Late July to mid-August in eastern Nebraska (Bray 1994), early June to mid-August in western Pennsylvania (Clench 1967). July to August in mountains of the Rocky Mountain states, May to August in the prairies (Ferris and Brown 1981). Late June to early August Washington and Oregon (Pyle 2002), mid-June to late July in Oregon (Warren 2005), late June to early August in British Columbia (Guppy and Shepard 2001).

Best determined by a combination of the overall dark brown base color with restricted yellow patches, the undersurface of the hindwing chestnut-brown with a broad postmedian patch of yellow spots surrounded by darker border, the central yellow spot jutting outward, a second smaller yellow patch near hindwing base.

Non-migratory.

Moist and dry grassy areas, montane meadows, prairie marsh edges, roadsides, urban lawns (Clench 1967; Scott 1986; Layberry et al. 1998; Opler and Wright 1999; Glassberg 2001; Pyle 2002); most abundant in degraded fields and barrens in midwestern prairie fragments (Swengel and Swengel 2015). Habitat in Montana not described but probably similar.

Larval food plants are grasses, including Distichlis spicata, Leersia oryzoides, and Poa pratensis, possibly Bromus inermis (Ferris and Brown 1981; Scott 1986, 1992, 2006; Layberry et al. 1998; James and Nunnallee 2011). Adults feed on flower nectar, including Achillea, Asclepias, Astragalus, Buddleja, Carduus, Centranthus, Ceratostigma, Chrysanthemum, Cirsium, Echinacea, Erigeron, Euphorbia, Gomphrena, Hesperis, Lavandula, Leucanthemum, Liatris, Lobelia, Lupinus, Lychnis, Malva, medicago, Nepeta, Prunella, Rudbeckia, Salvia, Scabiosa, Solidago, Sonchus, Symphoricarpos, Symphyotrichum, Tagetes, Taraxacum, Teucrium, Thermopsis, Trifolium, Verbena, Vernonia, Vicea, and Zinnia (Clench 1967; Bray 1994; Pyle 2002; James and Nunnallee 2011; Scott 2014).

Females lay eggs singly on or near host plant leaves; eggs drop to ground because they lack glue (Scott 1986, 1992; James and Nunnallee 2011). Eggs hatch in about 8-9 days, grow slowly in captivity from L1 instar to L3 instar in about 40 days, feed slowly another 30 days and diapause (overwinter) as half-grown (L3-L4 instars) or mature (L5 instar) larvae, possibly pupae. Larvae feed on host plant leaves, probably feed nocturnally, build silk-tied leaf-tube nests low on host plant or below ground, pupate in loose cocoon inside leaf nest near host plant base on in upper soil layer (Scott 1986, 1992; Guppy and Shepard 2001; James and Nunnallee 2011). Males perch throughout the day on tall grasses in grassy swales awaiting passing females (Scott 1986; James and Nunnallee 2011).