Montana Field Guide

[From Ferris and Brown 1981; Scott 1986; Layberry et al. 1998; Opler and Wright 1999; Glassberg 2001; Pyle 2002] Forewing 1.4-1.8 cm. Medium-sized, fringes dark brown on male hindwing. Uppersurface of forewing with grayish-brown patch at end of cell, clear spots appear in forewing band; male forewing with numerous raised grayish-white hairs over much of surface, creating a soft and frosted appearance, male hindlegs with tibial hair tufts; basal third of female forewing dark, with patches of gray on both sides of dark wing band, hindwing with small pale spots and less prominant cell-end bar.

One flight, mostly May to mid-June in the eastern US, mostly June in Canada and western US, June to July at high elevation; two flights, May to September in northern California, March to September in central California (Scott 1986). mainly May to July (Glassberg 2001). Mid-May to early August in Canada (Layberry et al. 1998). Mid-May through July in the Rocky Mountain states (Ferris and Brown 1981). Mid-May to mid-August in Colorado (Emmel 1964; Scott and Scott 1978; Scott and Epstein 1987), late April to early July in western Nebraska (Johnson and Nixon 1967), early May to late June in western North Dakota (McCabe and Post 1976), late April to mid-August in Oregon and Washington (Pyle 2002), mid-April to mid-August in Oregon (Warren 2005), early May to late June in British Columbia (Guppy and Shepard 2001).

Best determined by combination of distinctive genetalia; males with hind-leg tibial hair tufts and numerous raised grayish-white hairs over much of surface of forewing, creating a soft and frosted appearance; clear spots appear in forewing band,basal third of female forewing dark, with patches of gray on both sides of dark wing band, hindwing with small pale spots and less prominant cell-end bar.

Non-migratory.

Montane meadows, streamsides, woodland openings, roadsides, grasslands, sandy areas, above treeline in alpine terrain (Emmel 1964; Ferris and Brown 1981; Scott 1986; Layberry et al. 1998; Opler and Wright 1999; Glassberg 2001); also in ponderosa pine Pleistocene relict woodlands of the western Great Plains (Johnson and Nixon 1967; Johnson 1975). Habitat in Montana not described but probably similar.

Laval food plants are members of the Fabaceae, including Astragalus (multiple species), Lotus (multiple species), Lupinus (several species), Thermopsis (multiple species), and Trifolium, and members of the Salicaceae in eastern North America, including Populus (several species) and Salix (Scott 1986, 1992, 2006; Layberry et al. 1998; Guppy and Shepard 2001; Pyle 2002; Warren 2005; James and Nunnallee 2011). Adults feed on flower nectar (including Allium, Antennaria, Apocynum, Arctostaphylos, Astragalus, Barbarea, Berberis, Berteroa, Cerastium, Claytonia, Collinsia, Comandra, Cryptantha, Erigeron, Eriogonum, Erysimum, Harbouria, Heterotheca, Jamesia, Lathyrus, Lesquerella, Lithospermum, Lupinus, Mertensia, Oxytropis, Penstemon, Phacelia, Phlox, Physaria, Potentilla, Pseudostellaria, Pulsatilla, Ranunculus, Ribes, Sedum, Senecio, Thermopsis, Thlaspi, Townsendia, Verbena, Viola) and mud (Tooker et al. 2002; Warren 2005; James and Nunnallee 2011; Scott 2014).

Females lay eggs singly on the undersurface of host plant leaves, often near new growth and flower buds, sometimes on host plant stems (Scott 1986, 1992, 2006). Eggs hatch in about 7-8 days, develop from L2 instar to L5 instar in about 14 days, overwinters as mature L5 instar, pupate in about 6 days after exiting dormancy the following spring, adults eclose (emerge from pupae) in about 13 days (Guppy and Shepard 2001; James and Nunnallee 2011). Larvae feed on host plant leaves, build nests of rolled leaves tied with silk, feed nocturnally, overwinter (hibernate) as mature L5 instar (Scott 1979, 1986; James and Nunallee 2011). Males perch throughout the day on hilltops, the ground, low twigs near shrubs along flight corridors, awaiting passing females (Scott 1975b, 1986; Warren 2005; James and Nunnallee 2011).