Montana Field Guide

[From Ferris and Brown 1981; Scott 1986; Layberry et al. 1998, Opler and Wright 1999; Glassberg 2001; Pyle 2002] Forewing 1.5-1.6 cm. Antennal club short relative to antenna length. Uppersurface of forewing with black pattern extending inward in lobes between veins, male stigma with black interior felt; female with two elongate dark spots below discal cell; hindwing slightly translucent showing undersurface pattern. Undersurface of forewing with white spots in greenish-brown apical patch, hindwing dark yellow-brown to greenish-brown with orange along anal margin, large squarish and whitish spots in band, white spot in chevron closest to abdomen offset inwardly.

Two flights, mainly May to mid-June and September (Scott 1986). April to June, late August to early October (Glassberg 2001). April to June and August through September in the Rocky Mountain states (Ferris and Brown 1981), mid-May to late June and late August to early October in Colorado (Scott and Epstein 1987), late May to mid-July and mid-August to late October in California (Shapiro 1977, 1979), mid-April to early October on Oregon and Washington (Pyle 2002; Warren 2005), mid-May to June and September in British Columbia (Layberry et al. 1998).

Best determined by a combination of antennal club short relative to antenna length, uppersurface of forewing with black pattern extending inward in lobes between veins, undersurface of hindwing dark yellow-brown to greenish-brown with orange along anal margin, large squarish and whitish spots in band, white spot in chevron closest to abdomen offset inwardly.

Non-migratory, but perhaps migratory in some locations. Possibly wanders long distances, makes spring-summer elevational movements upslope (Pyle 2002; Warren 2005).

Sagebrush steppe, arid brushland, dunes, trailsides, grassy hillsides, pine-juniper woodland with grassy openings, dry and wet montane meadows, above treeline in alpine terrain (Emmel and Emmel 1962; Shapiro 1977; Scott 1986; Layberry et al. 1998; Opler and Wright 1999; Glassberg 2001; Guppy and Shepard 2001; Pyle 2002; Warren 2005). Habitat in Montana not described but probably similar.

Larval food plants are grasses, including Agropyron, Aristida, Bouteloua (multiple species), Bromus, Deschampsia, Koeleria, Poa (several species), and Stipa (Scott 1986, 1992; Pyle 2002; Warren 2005); also Elytrigia and Setaria in captivity (James 2009; James and Nunnalee 2011). Adults feed on flower nectar (including Allium, Balsamorhiza, Barbarea, Centaurea, Chrysothamnus, Erigeron, Eriogonum, Erysimum, Harbouria, Heterotheca, Liatris, Medicago, Physocarpus, Senecio, Symphyotrichum, Syringa) and mud (Pyle 2002; Warren 2005; Scott 2014).

Females lay eggs singly on or near dead host plant on inflorescense, base of grass clump, sometimes on soil (Scott 1986, 1992; James and Nunnallee 2011). Summer eggs hatch in about 7-14 days, may diapause (overwinter) with well-formed L1 instar if laid late in season and hatch following spring. Larvae develop to L2 instar in about 7 days (depending on temperature), to L5 instar in another 35 days. Spring-laid eggs develp to L5 instar in about 37 days, L5 instar undergoes summer dormancy for about 31 days before pupation in a silk cocoon, sometimes grow to L6 instar before pupation, adults eclose (emerge from pupae) in about 15-16 days. Larvae feed on host plant leaves, live in silk-tied leaf tube-nest, rest in nest when not feeding, overwinter (diapause) as fully-developed egg or L2 instar, sometimes L1 or L3 instars (Scott 1979, 1986, 1992; James 2009; James and Nunnallee 2011); adult possibly overwinters under some circumstances (Shapiro 1979; Berkhousen and Shapiro 1994), but the likelihood of this has been questioned (Scott 1992; Warren 2005; James 2009). Males territorial, perch throughout the day on ground or low vegetation in gullies, rocky depressions, valley bottoms awaiting passing females (Scott 1975b, 1986; James and Nunnallee 2011).