Montana Field Guide

[From Ferris and Brown 1981; Scott 1986; Opler and Wright 1999; Glassberg 2001] Forewing 1.8-2.8 cm. Uppersurface orange on both sets of wings with irregular black borders on costal and outer margins; orange-yellow form rare; male with black border sharply defined, female with inner edge of black border diffuse (especially on hindwing); forewing with small black cell spot. Undersurface of forewing with orange flush, hindwing in summer form orange-yellow with diagonal postmedian brown smudges, in winter form dull reddish.

Several flights all year in southern California, southern Texas, southern Florida; migratory northward, mostly summer records (Scott 1986). All year, central Texas to southeastern Arizona, March to September in southern California; mainly June through July elsewhere (Glassberg 2001). Early June to early August in Colorado (Brown 1957; Emmel 1964; Scott and Scott 1978), mid-June to early July in Wyoming (Hardesty and Groothuis 1993), early September to late February in Hawaii (Rubinoff et al. 2015).

Best determined by a combination of dull to bright orange uppersurface with irregular black borders on costal and outer margins; male with black border sharply defined, female with inner edge of black border diffuse (especially on hindwing); forewing with small black cell spot; undersurface of hindwing with diagonal postmedian brown smudges.

Migratory. Movements primarily northward in autumn (Scott 1986; Walker 2001). Established on Oahu in 2013, since spread to several of the main Hawaiian Islands (Rubinoff et al. 2015).

Low areas in subtropical regions, dry washes, prairie, pine forest, open fields, farm land, roadsides, many other open habitats including above treeline in alpine terrain (Brown 1957; Emmel 1964; Scott and Scott 1978; Ferris and Brown 1981; Scott 1986; Opler and Wright 1999; Glassberg 2001; Rubinoff et al. 2015). Habitat in Montana not described but probably similar.

Larval foodplants are exotic and native members of the pea family, including Cassia (several species) and Trifolium (Ferris and Brown 1981; Scott 1986, 1992; Guppy and Shepard 2001; Graves and Shapiro 2003; Rubinoff et al. 2015); adults visit other legumes but egg-laying not reported (Scott 2006). Adults feed on flower nectar (including Cardamine, Cirsium, Erigeron, Oxalis, Psilostrophe, Raphanus, Sedum, Symphyotrichum, Trifolium, Verbena, Viola) and mud (Tooker et al. 2002; Scott 2014; Rubinoff et al. 2015).

Limited information. Females lay eggs singly on the underside of host plant leaves, sometimes on flower buds. Larvae eat host plant leaves, overwinter as adult only in the southern part of North American range (Scott 1979, 1986, 1992). Males patrol throughout the day mainly in gulches and over flat terrain in search of females (Scott 1975b, 1986).