Montana Field Guide

[From Ferris and Brown 1981; Scott 1986; Layberry et al. 1998; Opler and Wright 1999; Glassberg 2001; Pyle 2002] Forewing 1.3-1.5 cm. Uppersurface tawny orange, lacking white spots but with dark brown border projecting inward between veins, male forewing with prominent black stigma imbedded in dark diagonal band from wing base to somewhat rounded tip, female forewing with a dark diagonal band and no stigma. Undersurface variable (yellow, purple, chocolate-brown), hindwing usually yellow-orange with postmedian chevron of pale squarish yellow or yellow-cream spots.

One flight, mostly late July through August (late August to early October in California); multiple flights April to October at lower elevation in California (Scott 1986). Mid-June to early October, mainly August through September (Glassberg 2001). June to September in Canada (Layberry et al. 1998). Mid-July through August in the Rocky Mountain states (Ferris and Brown 1981), mid-July to late September in Colorado (Scott and Epstein 1987), mid-August to mid-September in the Black Hills of South Dakota (McCabe and Post 1976), mid-June to early October in Oregon and Washington (Pyle 2002), late June to early October in Oregon (Warren 2005), late July to mid-September in British Columbia (Threatful 1988; Guppy and Shepard 2001).

Best determined by a combination of the uppersurface with dark brown border projecting inward (tooth-like) between veins, both sexes with a dark diagonal band from wing base to tip, encompassing a prominent black stigma in the male; undersurface of the hindwing variable in color, usually yellow-orange with postmedian chevron of pale and large squarish yellow or yellow-cream spots.

Non-migratory.

Hillsides, grassy areas in chaparral, sagebrush, montane meadows, gardens, along streams and roadways (Scott 1986; Threatful 1988; Opler and Wright 1999; Glassberg 2001; Pyle 2002; Warren 2005). Habitat in Montana not described but probably similar.

Larval food plants are native and exotic grasses, including Agropyron (several species), Agrostis (multiple species), Avena, Bromus (several species), Cynodon, Dactylis, Danthonia, Elymus (multiple species), Leucanthemum, Leucopoa, Leymus (several species), Muhlenbergia, Phalaris (multiple species), Phleum, Pseudoroegneria, possibly Calamagrostis, and Poa in captivity (Scott 1986, 1992, 2006; Pyle 2002; Graves and Shapiro 2003; Warren 2005; James and Nunnallee 2011); anomalous oviposition reported on the shrub Ceanothus cuneatus (Shapiro 2013). Adults feed on flower nectar (including Achillea, Alyssum, Anaphalis, Arctium, Asclepias, Astragalus, Berteroa, Buddleia, Carduus, Centaurea, Cerastium, Chamaenerion, Chrysanthemum, Chrysothamnus, Cichorium, Cirsium, Dipsacus, Epilobium, Ericameria, Erigeron, Eriogonum, Geranium, Grindelia, Helianthus, Heterotheca, Lathyrus, Lavandula, Leontodon, Liatris, Linaria, Lythrum, Machaeranthera, Medicago, Mentha, Monarda, Nepeta, Phlox, Polygonum, Prunella, Solidago, Sonchus, Symphyotrichum, Tagetes, Tanacetum, Trifolium, Verbena, Viguiera, Zinnia) and mud (Scott 1986, 2014; Pyle 2002; Warren 2005; Shapiro 2013).

Females lay eggs singly on the undersides of dead host plant leaves, typically 10-60 cm above ground (Scott 1992; James and Nunnallee 2011). L1 instar hatches from egg in about 7-18 days (depending on temperature), L1 instar overwinters in silk-tied leaf-tube shelter, emerges from diapause in spring, develop from L1 instar to L5 instar and pupa in about 44 days, adults eclose (emerge from pupae) in about 6-10 days. Larvae depart nests to feed on host plant leaves, feed nocturnally but may become more active during day as larvae mature, mature (L5 instar) larvae may aestivate for about 30 days prior to pupation, pupates in new leaf-nest (Scott 1979, 1986; James and Nunnallee 2011). Males perch throughout the day about 1 m above ground in gullies, valley botttoms, among shrubs on ridges, awaiting passing females (Scott 1975b, 1986).