Montana Field Guide

[From Ferris and Brown 1981, Scott 1986, Glasberg 2001, Guppy and Shepard 2001, Pyle 202] Forewings 2.5-3.0 cm. Rich brown-orange over most of dorsal surface, with yellow highlights and black spots and patches; wing margins hoary, black border has short rounded tails on hindwings, dorsal hindwing clear orange with black spot on leading edge but no prominent white bar; ventral surface bark-brown with striations and variable white marbling, lighter outward and darker toward the wing base. Forelegs of male hairier than those of female.

Varies. One flight in Colorado, adults active July to October when they hibernate (Ferris and Brown 1981). Three or more flights in California; adults emerge from hibernation in February to early April, produce the first flight in late May to early June, second flight July-August, third flight in late September to October (Scott 1986). In Washington and Oregon, late January to mid-November, with peaks in April and August related to different cohorts (Pyle 2002).

Most similar to Compton Tortoiseshell (Nymphalis vaualbum), but lacks a white bar on dorsal hindwing, has a black dorsal hindwing margin, and is more heavily marked dorsally with bright orange.

Migratory, with large immigrant influxes from multiple flights some years (Scott 1986, Guppy and Shepard 2001, Pyle 2002). Migrates north and east in May in central California, south and west in September and October, although early and late migrations comprised of individuals in different cohorts (Shapiro 1975).

Lower montane chaparral, canyon bottoms, ponderosa pine woodland clearings and trails, but almost any habitat during irruption years, including urban areas and above treeline in alpine terrain (Knaus and Lambremont 1987, Shields 1987, Pyle 2002, Hendricks 2005); reported in alpine terrain in Glacier National Park (Debinski 1993).

Larval food plants include several species of Ceanothus (Scott 1986, Pyle 2002). Adults feed on flower nectar, sap, fruit, and mud.

Overwinters (hibernates) as adult. Females deposit eggs on the underside of leaves, sometimes in small clusters. Eggs hatch in 4-5 days. Development rapid at certain temperatures, pupation 25-27 days after eggs hatch, with 5, 3, 4, 5, and 10 days spent in L1, L2, L3, L4, and L5 instars, respectively. Adults emerge from pupae in 6-11 days, about 5 weeks after oviposition. Larvae do not make nests, but early instars may cover themselves by joining leaves together; larvae feed openly on vegetation (James and Nunnallee 2011). Adult males perch during mid-day to late afternoon on branches in valley bottoms to await passing females (Scott 1986).