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Dreamy Duskywing - Erynnis icelus
Native Species
Global Rank:
G5
State Rank:
S5
Agency Status
USFWS:
USFS:
BLM:
External Links
General Description
[From Ferris and Brown 1981; Scott 1986; Layberry et al. 1998; Opler and Wright 1999; Glassberg 2001; Pyle 2002] Forewing 1.4-1.5 cm. Small for a duskywing. Base color black. Labial palpi project forward more than other Erynnis (duskywings), forewing with slight hump along leading edge (costa) in males, lack small transparent white spots. Uppersurface of forewings grizzled gray with darker chain-like median and postmedian bands, inner 1/3 blacker than rest of ground color; hindwing crossed with small buffy spots.
Phenology
One flight, mid-May to mid-June most areas, late April to June in southeast, late-May to early July in the north and higher elevations (Scott 1986). May to mid-July (Glassberg 2001). Mid-May to early July in Canada (Layberry et al. 1998). Late April to early July in the Rocky Mountain states (Ferris and Brown 1981). Mid-May to mid-July in Colorado (Scott and Scott 1978), early May to late June in North Dakota (McCabe and Post 1976), early April through late July in Oregon and Washington (Pyle 2002; Warren 2005), early May to late June in British Columbia (Threatful 1988; Guppy and Shepard 2001).
Diagnostic Characteristics
Best determined by a combination of small size for a duskywing, labial palpi project forward more than in other duskywings, forewing of males with slight hump along leading edge (costa), uppersurface of forewing without small transparent white spots, frosty scaling traversed by darker chain-like median and postmedian bands, inner 1/3 blacker than rest of ground color.
Species Range
Montana Range
Range Descriptions
Native
Range Comments
Across boreal Canada from the Northwest Territories to Nova Scotia, south in the West to central California, southern Arizonas and southern New Mexico, south in the East to Arkansas, northeastern Alabama, northern Georgia (Scott 1986; Layberry et al. 1998; Opler and Wright 1999; Glassberg 2001); to 3048 m elevation in the Rocky Mountain states (Ferris and Brown 1981), 2134 m to 3048 m elevation in Colorado (Brown 1957; Scott and Scott 1978), sea level to at least 2134 m elevation in Oregon and Washington (Warren 2005; James and Nunnallee 2011), below 1000 m elevation in British Columbia (Threatful 1988; Guppy and Shepard 2001). In Montana, reported from at least 33 counties across the state (Kohler 1980; Stanford and Opler 1993; FLMNH Lepidopterists' Society database), to at least 1981 m elevation. Common, Canada and Montana, mainly rare to uncommon elsewhere (Glassberg 2001).
Observations in Montana Natural Heritage Program Database
Number of Observations: 15
(Click on the following maps and charts to see full sized version)
Map Help and Descriptions
Relative Density
Recency
(Observations spanning multiple months or years are excluded from time charts)
Migration
Non-migratory.
Habitat
Open woodlands, aspen woodland, stream margins, road margins, moist forest edge (Ferris and Brown 1981; Scott 1986; Threatful 1988; Layberry et al. 1998; Opler and Wright 1999; Glassberg 2001; Guppy and Shepard 2001). Habitat in Montana not described but probably similar.
Food Habits
Larval food plants are members of the Salicaceae, including Populus (several species) and Salix (several species), Betulaceae, including Betula, and Fabaceae, including Robinia (Ferris and Brown 1981; Scott 1986, 1992, 2006; Layberry et al. 1998; Warren 2005; James and Nunnallee 2011). Adults feed on flower nectar (including Antennaria, Astragalus, Cerastium, Cercis, Claytonia, Collinsia, Erigeron, Lithospermum, Phlox, Prunus, Senecio, Trifolium, Viola), campfire ash, and mud (Scott 1986, 2014; Pyle 2002; Tooker et al. 2002; James and Nunnallee 2011).
Reproductive Characteristics
Females lay eggs singly on the undersides of young (seedling) host plant leaves (Scott 1986, 1992, 2006; James and Nunnallee 2011); 50 eggs laid by one captive female in five days. Eggs hatch in about 5-7 days (depending on temperature), develop to L5 instar in about 19 days post egg-hatch (depending on temperature), pupate in 19 days after reaching L5 instar, eclose (emerge from pupae as adult) in 16 days (James and Nunnallee 2011). Larvae feed on host plant leaves, live in folded leaf-flap nests when L1-L2 instars, silked-together leaves when L3-L5 instars, feed outside nests at night, overwinter (diapause) as mature L5 instar (Scott 1979, 1986; James and Nunnallee 2011). Males perch, occasionally patrol, throughut the day in shallow depressions, gullies, often perch on dead woody material near host plants waiting or searching for passing females (Scott 1975b, 1986; James and Nunnallee 2011); do not hilltop (Ferris and Brown 1981; Glassberg 2001).
Stewardship Responsibility
References
- Literature Cited AboveLegend:
View Online Publication
Brown, F.M. 1957. Colorado Butterflies. Proceedings; Numbers Three through Seven. Denver Museum of Natural History, Denver, Co.- 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.
- McCabe, T.L. and R.L. Post. 1976. North Dakota butterfly calendar (including possible strays). Journal of Research on the Lepidoptera 15:93-99.
- 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. 1979. Hibernal diapause of North American Papilionoidea and Hesperioidea. Journal of Research on the Lepidoptera 18(3): 171-200.
- Scott, J.A. 1986. The butterflies of North America: a natural history and field guide. Stanford University Press, Stanford, California.
- Scott, J.A. 1992. Hostplant records for butterflies and skippers (mostly from Colorado) 1959-1992, with new life histories and notes on oviposition, immatures, and ecology. Papilio new series #6. 185 p.
- 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.
- Scott, J.A. and G.R. Scott. 1978. Ecology and distribution of the butterflies of southern central Colorado. Journal of Research on the Lepidoptera 17(2): 73-128.
- 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.
- Tooker, J.F., P.F. Reagel, and L.M. Hanks. 2002. Nectar sources of day-flying lepidoptera of central Illinois. Annals of the Entomological Society of America 95(1): 84-96.
- 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
Do you know of a citation we're missing?- 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.
- Forister, M.L., C.A. Halsch, C.C. Nice, J.A. Fordyce, T.E. Dilts, J.C. Oliver, K.L. Prudic, A.M. Shapiro, J.K. Wilson, J. Glassberg. 2021. Fewer butterflies seen by community scientists across the warming and drying landscapes of the American West. Science 371:1042-1045.
- Forister, M.L., E.M. Grames, C.A. Halsch, K.J. Burls, C.F. Carroll, K.L. Bell, J.P. Jahner, et al. 2023. Assessing risk for butterflies in the context of climate change, demographic uncertainty, and heterogeneous data sources. Ecological Monographs 93(3):e1584. https://doi.org/10.1002/ecm.1584
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