Montana Field Guide

[From Ferris and Brown 1981; Scott 1986; Glassberg 2001; Pyle 2002] Forewing 2.9-4.0 cm. A mid-sized to large fritillary. Tawny orange to bright orange dorsally, sometimes with postmedian and marginal spots lighter than surrounding ground color, males with light black chains along wing margins, females with heavy black chains; ventral forewing usually reddish-orange flush (especially females), hindwing marginal silver spots inwardly rounded (almost egg-shaped, not tent-like or triangular) and capped with greenish-brown, other underwing silver spots large and round, hindwing disk color brown, submarginal band straw-yellow or pale buff.

One flight; June to early September (Scott 1986), early May to mid-October in Oregon and Washington (Pyle 2002; James and Nunnallee 2011), late May to early September east of the continental divide in Colorado (Glassberg 2001).

Distinguished from other large fritillaries by hindwing marginal silver spots inwardly rounded (almost egg-shaped, not tent-like or triangular) and capped with greenish-brown, the underwing submarginal band straw-yellow or pale buff.

Mostly Non-Migratory, but an altitudinal migrant in Oregon coastal lowlands, making elevational movements upslope in midsummer and returning in late summer (Scott 1986). In central Washington the same altitudinal migration reported, mostly by females, who travel 50-100 km between lowland and montane sites (James and Pelham 2011).

Chaparral, sagebrush steppe, conifer woodland, montane meadows (Scott 1986; Pyle 2002; James and Pelham 2011).

Larval food plants include several species of violet (Viola) (Scott 1986; Pyle 2002; James and Nunnallee 2011). Adults feed on flower nectar (including Apocynum, Aster, Astragalus, Barbarea, Carduus, Centaurea, Chrysothamnus, Cirsium, Erigeron, Erioganum, Erysimum, Gaillardia, Heracleum, Jamesia, Lesquerella, Liatris, Medicago, Monarda, Oxytropis, Physocarpus, Sedum, Senecio, Solidago, Taraxacum, Verbena) and sip mud (Scott 1986, 2014).

Females lay eggs in fall (September and October in central Washington), usually singly but sometimes in close proximity, on rocks, bare earth, ground-level trunks and stems of sagebrush in areas with concentrations of desiccated violets. Eggs laid 5-25 cm apart, then female moves to another location 5-30 m distant. Eggs hatch in about 14-20 days (depending on temperature), larvae diapause (overwinter) as L1 instar. L1 molt to L2 in about 8-9 days, L2-L6 and to pupation in about 31 days; larvae solitary, build no nests, rest on undersides of leaves, and feed nocturnally. Adults eclose (emerge from pupae) in about 12 days (James and Nunnallee 2011; James and Pelham 2011). Males patrol rapidly and low over the ground throughout the day in all areas, regardless of topography (Scott 1975b, 1986; James and Pelham 2011).