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Montana Field Guides

Dreamy Duskywing - Erynnis icelus


Global Rank: G5
State Rank: S5

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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

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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).

Summary of Observations Submitted for Montana
Number of Observations: 1

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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).

References
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Citation for data on this website:
Dreamy Duskywing — Erynnis icelus.  Montana Field Guide.  .  Retrieved on , from