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Montana Field Guides

Great Basin Fritillary - Speyeria egleis


Global Rank: G5
State Rank: S5

Agency Status
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General Description
[From Ferris and Brown 1981; Scott 1986; Opler and Wright 1999; Glassberg 2001; Pyle 2002] Forewing 2.3-3.4 cm. Variable; a small to middle-sized greater fritillary. Uppersurface orange with black spots and bars, dark forewing margins, basal half of wings darkened; undersurface with brown disk (pale to dark brown to greenish) usually mottled in appearance, postmedian silvery spots smaller than in most Speyeria and relatively elongate, marginal spots slightly triangular or rounded with brown or greenish caps.

Phenology
One flight; late June to mid-August (Scott 1986); June to September (Glassberg 2001); mid-June to early September (Pyle 2002).

Diagnostic Characteristics
Determined by a combination of smoky or hazy dorsal appearance on the upper surface, heavy dark scaling on the basal half of upperwings, under hindwing disk with greenish overtones and red-brown color, smaller size and elongated appearance of postmedian under hindwing spots, underwing marginal spots slightly triangular with brown or greenish caps.

Species Range
Montana Range

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Range Comments
Eastern Washington, Idaho, and western Montana south to southwestern Oregon and northern California in the Cascades, southern California in the Sierra Nevada, central Nevada in the Great Basin, and central Utah and northern Colorado in the Rocky Mountains (Scott 1986, Glassberg 2001; James and Nunallee 2011); 610-3050 m elevation. Throughout the mountainous western third of Montana (Kohler 1980; Stanford and Opler 1993), to at least 2135 m elevation (Ferris and Brown 1981; Debinski 1993). Uncommon to common, sometimes abundant in Sierra Nevada, California (Glassberg 2001); uncommon in Greater Yellowstone Ecosystem (Debinski and Pritchard 2002).

Summary of Observations Submitted for Montana
Number of Observations: 5

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Relative Density

Recency

 

(Observations spanning multiple months or years are excluded from time charts)



Migration
Non-migratory.

Habitat
Varies with subspecies. To high elevation in montane forest openings and meadows, stream banks, exposed rocky ridges, pumice flats (Ferris and Brown 1981; Scott 1986; Pyle 2002; James and Nunnallee 2011). Forest openings and exposed rocky ridges in the Greater Yellowstone Ecosystem (Debinski and Pritchard 2002); montane wet meadows and above treeline in alpine terrain in Glacier National Park (Debinski 1993).

Food Habits
Larval food plants include several species of Viola (Scott 1986; Pyle 2002; James and Nunnallee 2011). Adults feed on flower nectar (including Achillea, Agastache, Apocynum, Calyptridium, Chrysothamnus, Cirsium, Prunus, Senecio) and mud (Ferris and Brown 1981; Pyle 2002; James and Nunnallee 2011; Scott 2014).

Reproductive Characteristics
Females lay eggs singly on or near host plants. Eggs hatch in about 15 days (depending on temperature), larvae diapause (overwinter) as L1 instars. L1 emerge from diapause in spring and reach L2 in 8 days, another 34 days to pupate, an additional 12 days to eclose (emerge from pupae). Most larval feeding is nocturnal. Larvae are solitary, do not build nests but seek refuge as L1 in curled leaves and dried seedpods; mature larvae silk together leaves as pupation tents close to the ground, many pupae fall to the ground (Scott 1986; James and Nunnallee 2011). Males patrol throughout the day low to the ground in shaded open spaces (including roads) or hilltops as they seek females (Scott 1975b, 1986).

References
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Citation for data on this website:
Great Basin Fritillary — Speyeria egleis.  Montana Field Guide.  .  Retrieved on , from