Montana Field Guide

[From Ferris and Brown 1981; Scott 1986; Glassberg 2001, Guppy and Shepard 2001; Pyle 2002] Forewing 1.6-2.1 cm. Antennae knobs dark brown or black. Upperside orange and black, appearing primarily black above, hindwing postmedian orange band enclosing black dots; underside of forewing yellow-brown with a yellow discal bar and smaller black patches on the inner margin, underside of hindwing yellow-brown with rusty markings and more heavily patterned.

Three or four flights: one flight from late June to early August in the mountains and far north, three to four flights in May to September on the Colorado plains, April-October in lowland California (Scott 1986). One flight early May to late September in the Pacific Northwest (Pyle 2002; James and Nunallee 2011), one flight late May to early August in British Columbia (Guppy and Shepard 2001).

Best told by the upper surface being relatively black in the basal and median regions of the wings, the underside of forewing with a yellow bar at the outer end of the discal cell running perpendicular to leading edge of wing, antennal knobs largely dark brown or black.

Non-migratory.

Prairie, forested foothills, moist montane meadows, taiga, above treeline in alpine tundra (Scott 1986; Pyle 2002; James and Nunnallee 2011). In Glacier National Park, Montana reported in mesic montane meadows and above treeline in alpine tundra (Debinski 1993).

Larval food plants include many species of aster (Aster, Eucephalius, Eurybia, Machaeranthera)(Scott 1986, 1992; Guppy and Shepard 2001; Pyle 2002), but also on Taraxacum in captivity (James and Nunnallee 2011). Adults feed on flower nectar (including Achillea, Allium, Antennaria, Apocynum, Arnica, Aster, Astragalus, Bidens, Ceanothus, Centaurea, Cerastium, Chrysothamnus, Cirsium, Cryptantha, Erigeron, Erioganum, Erysimum, Galium, Grindelia, Helianthus, Lesquerella, Machaeranthera, Potentilla, Prunus, Ranunculus, Rudbeckia, Sedum, Senecio, Solidago, Taraxacum, and Trifolium) as well as dung and mud (Scott 1992; Pyle 2002, James and Nunnallee 2011).

Females lay eggs in clusters (to 235 eggs per cluster but usually 30-40 eggs) on the undersides of host plant leaves, sometimes very close to the ground. Eggs hatch in 6-9 days. Larvae gather into groups and cover themselves in communal silk nests. Feeding occurs both diurnally and nocturnally. Larvae reach L3 instars by about 36-40 days post egg hatch, at which stage they diapause. Development to L4 instar began about 26 days after overwintwering completed, L5 in another 11 days, and pupation in 20 days after molting to L5; adults emerge from pupae (eclose) in abut 33-40 days, depending on temperature (Scott 1992; James and Nunnallee 2011). Males patrol for females low to the ground throughout the day in grassy swales, meadows, valley bottoms (Scott 1975b, 1986).