Two-banded Checkered-skipper - Pyrgus ruralis
[From Ferris and Brown 1981; Scott 1986; Layberry et al. 1998; Opler and Wright 1999; Glassberg 2001; Pyle 2002] Forewing 1.2-1.3 cm. Small, fringes checkered. Male forewing with costal fold. Uppersurface black with small white spots, the white submarginal and median spot-bands of the forewing somewhat parallel and forming an apparent "X", the spot bands on the hindwing parallel, the hindwing with a very small white postbasal spot. Undersurface of hindwing with interspersed white and reddish-brown bands.
One flight, mostly May in coastal ranges and low elevations, mid-June through mid-July at high elevation, mid-April to mid-July for southern California Pyrgus ruralis lagunae (Scott 1986). June to mid-July in the Rocky Mountain region, March to August elsewhere except April and May in southern California (Glassberg 2001). Early May to mid-July in Canada (Layberry et al. 1998). Mid-May to early July in the Rocky Mountain states (Ferris and Brown 1981). June to mid-July in northern California (Emmel and Emmel 1962; Shapiro 1977), early March to early September in Oregon and Washington (Pyle 2002), late March to mid-August in Oregon (Warren 2005), April to mid-July in British Columbia (Threatful 1988; Guppy and Shepard 2001).
Best determined by a combination of small size, dark uppersurface with white submarginal and median spot bands forming an "X" on the forewing, the uppersurface of the hindwing with a small white postbasal spot; undersurface of hindwing with interspersed white and reddish-brown bands.
Southern British Columbia and southwestern Alberta south in the mountains to central California, southern Utah, central Colorado (Scott 1986; Layberry et al. 1998; Opler and Wright 1999; Glassberg 2001); to 3200 m elevation in the Rocky Mountain states (Ferris and Brown 1981), to at least 2743 m elevation in northern California (Emmel and Emmel 1962; Shapiro 1977), sea level to 2896 m elevation in Oregon (Warren 2005), to at least 1830 m elevation in Washington (James and Nunnallee 2011), to 2000 m elevation in British Columbia (Layberry et al. 1998; Guppy and Shepard 2001). In Montana, reported from at least 29 counties in the western 1/2 of the state, east to Fergus and Carbon counties (Kohler 1980; Stanford and Opler 1993; FLMNH Lepidopterists' Society database), to at least 1410 m elevation. Rare to uncommon in the Rocky Mountain region (Glassberg 2001).
Wet and dry montane meadows, forest clearings, hillsides, roadsides, creek and river margins, above treeline in alpine terrain (Emmel and Emmel 1962; Shapiro 1977; Ferris and Brown 1981; Scott 1986; Threatful 1988; Layberry et al. 1998; Opler and Wright 1999; Glassberg 2001; Pyle 2002; Warren 2005). Habitat in Montana not described but probably similer.
Larval food plants are members of the Rosaceae including Fragaria and Potentilla (multiple species), possibly Geum and Horkelia, members of the Malvaceae including Sidalcea, in captivity members of the Ericaceae including Vaccinium (Ferris and Brown 1981; Scott 1986, 2006; Layberry et al. 1998; Guppy and Shepard 2001; Pyle 2002; James and Nunnallee 2011). Adults feed on flower nectar (including Dentaria, Fragaria, Potentilla, Taraxacum) and mud (Pyle 2002; Warren 2005; James and Nunnallee 2011; Scott 2014).
Females lay eggs singly on the undersides of host plant leaves (Scott 1986; James and Nunnalee 2011). Eggs hatch in 3-4 days (depending on temperature), develop from L1 instar to L5 instar and pupae in 32 days (low elevation cohorts) to 55 days (high elevation cohorts), depending on temperature for both cohorts. Overwinter as pupae, adults eclose (emerge from pupae) in about 62 days following exposure to warm spring temperatures. Larvae feed on host plant leaves, build silk-tied tube nests of host plant leaves, may cannibalize smaller larvae, pupate in late summer-early autumn in heavily silk-lined L5 instar nest (James and Nunnallee 2011). Males patrol or perch near the ground throughout the day in valley bottoms and grassy swales in search of or awaiting passing females (Scott 1975b, 1986; Warren 2005).
- Literature Cited AboveLegend: View Online Publication
- Emmel, T.C. and J.F. Emmel. 1962. Ecological studies of Rhopalocera in a High Sierran Community-Donner Pass, California. I. Butterfly associations and distributional factors. Journal of the Lepidopterists' Society 16:23-44.
- Ferris, C.D. and F.M. Brown (eds). 1981. Butterflies of the Rocky Mountains. Univ. of Oklahoma Press. Norman. 442 pp.
- Glassberg, J. 2001. Butterflies through Binoculars: A Field Guide to the Butterflies of Western North America. Oxford University Press.
- Guppy, C.S. and J.H. Shepard. 2001. Butterflies of British Columbia: including western Alberta, southern Yukon, the Alaska Panhandle, Washington, northern Oregon, northern Idaho, northwestern Montana. UBC Press (Vancouver, BC) and Royal British Columbia Museum (Victoria, BC). 414 pp.
- James, D.G. and D. Nunnallee. 2011. Life histories of Cascadia butterflies. Corvallis, OR: Oregon State University Press. 447 p.
- Kohler, S. 1980. Checklist of Montana Butterflies (Rhopalocera). Journal of the Lepidopterists' Society 34(1): 1-19.
- Layberry, R.A., P.W. Hall, and J.D. LaFontaine. 1998. The Butterflies of Canada. University of Toronto Press. 280 pp. + color plates.
- Opler, P.A. and A.B. Wright. 1999. A field guide to western butterflies. Second edition. Peterson Field Guides. Houghton Mifflin Company, Boston, Massachusetts. 540 pp.
- Pyle, R.M. 2002. The butterflies of Cascadia: a field guide to all the species of Washington, Oregon, and surrounding territories. Seattle Audubon Society, Seattle, Washington. 420 pp.
- Scott, J.A. 1975b. Mate-locating behavior of western North American butterflies. Journal of Research on the Lepidoptera 14:1-40.
- Scott, J.A. 1986. The butterflies of North America: a natural history and field guide. Stanford University Press, Stanford, California.
- Scott, J.A. 2006. Butterfly hostplant records, 1992-2005, with a treatise on the evolution of Erynnis, and a note on new terminology for mate-locating behavior. Papilio new series #14. 74 p.
- Scott, J.A. 2014. Lepidoptera of North America 13. Flower visitation by Colorado butterflies (40,615 records) with a review of the literature on pollination of Colorado plants and butterfly attraction (Lepidoptera: Hersperioidea and Papilionoidea). Contributions of the C.P. Gillette Museum of Arthopod Diversity. Fort Collins, CO: Colorado State University. 190 p.
- Shapiro, A.M. 1977. The alpine butterflies of Castle Peak, Nevada County, California. Great Basin Naturalist 37(4): 443-452.
- Stanford, R.E. 1981. Hesperiodea. In: Ferris, C.D. and F.M. Brown. Butterflies of the Rocky Mountain States. University of Oklahoma Press, Norman. pp. 67-140.
- Stanford, R.E. and P.A. Opler. 1993. Atlas of western USA butterflies: including adjacent parts of Canada and Mexico. Unpubl. Report. Denver and Fort Collins, Colorado 275 pp.
- Threatful, D.L. 1988. A list of the butterflies and skippers of Mount Revelstoke and Glacier National Parks, British Columbia, Canada (Lepidoptera). Journal of Research on the Lepidoptera 27(3-4): 213-221.
- Warren, A.D. 2005. Lepidoptera of North America 6: Butterflies of Oregon, their taxonomy, distribution, and biology. Contributions of the C. P. Gillette Museum of Arthropod Diversity, Colorado State University. Fort Collins, Colorado. 406 pp.
- Additional ReferencesLegend: View Online Publication
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- Allen, T.J., J.P. Brock, and J. Glassberg. 2005. Caterpillars in the field and garden: a field guide to the butterfly caterpillars of North America. Oxford University Press.
- Brock, J.P. and K. Kaufman. 2003. Kaufman Field Guide to Butterflies of North America. Houghton Mifflin Company, New York, NY 284 pp.
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