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Montana Field Guides

Half-moon Hairstreak - Satyrium semiluna
Other Names:  Satyrium fuliginosa semiluna


Global Rank: G4
State Rank: S4

Agency Status
USFWS:
USFS:
BLM:


 

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General Description
[From Ferris and Brown 1981; Scott 1986; Opler and Wright 1999; Glassberg 2001; Pyle 2002] Forewing 1.3-1.4 cm. Tailless. Uppersurface gray to brown, unmarked, lacks strong dark bar at end of forewing cell, fringe of forewing light gray to light tan. Undersurface of hindwing sooty gray, an obscure irregular postmedian series of small black spots circled with white, an even more obscure submarginal series of spots, a small obscure whitish bar in the discal cell.

Phenology
One flight; mainly July (Scott 1986). May to mid-September but mainly July and August (Glassberg 2001). Late May to late August and early September in Oregon and Washington (Pyle 2002; Warren 2005), late May to early July in British Columbia (Guppy and Shepard 2001).

Diagnostic Characteristics
Best determined by the uppersurface lacking the strong dark bar at end of forewing cell, the under hindwing with an obscure irregular postmedian series of small black spots circled with white, an even more obscure submarginal series of spots, a small obscure whitish bar in the discal cell.

Species Range
Montana Range

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Range Comments
Extreme southern British Columbia south to northeastern California, northern Nevada, and east across southern Idaho, southwestern Montana, western Wyoming to northern Utah and Colorado (Scott 1986; Opler and Wright 1999; Glassberg 2001; Brock and Kaufman 2003); usually between 2286 m and 2743 m elevation in Rocky Mountain states (Ferris and Brown 1981), 549 m to 2591 m elevation in Oregon (Warner 2005). In Montana, reported from at least nine counties in the southwestern part of the state (Kohler 1980; Stanford and Opler 1993). Uncommon to common (Glassberg 2001).

Migration
Non-migratory.

Habitat
Sagebrush steppe on hills and slopes, montane meadows, roadsides, pine forest openings (Scott 1986; Opler and Wright; Glassberg 2001; Pyle 2002). Reported from meadows in pine forest, dry mountainsides, rolling grassland, roadsides in the Greater Yellowstone Ecosystem (Debinski and Pritchard 2002).

Food Habits
Larval food plants include at least eight species of Lupinus (Scott 1986, 1992; James and Nunnallee 2011). Adults feed on flower nectar, including Arnica, Eriogonum, Purshia, Senecio, and Tetradymia (Pyle 2002; Scott 2014).

Reproductive Characteristics
Females lay eggs singly or in small clusters low on host plant stem or in litter near base (Scott 1986, 1992; James and Nunnallee 2011). Eggs overwinter, hatch within 2 days after exiting diapause (depending on temperature). Larval L1 instar reaches L2 and L3 instar in 4-5 days post-hatch, L4 in 9 days post-hatch, pupate 19-20 days post-hatch. Adults eclose (emerge from pupa) in 13 days (33 days post-hatch). Larvae build no nests, are nocturnal, feed on leaves, flowers, in stems, may be tended by ants (Scott 1979, 1986, 1992; James and Nunnallee 2011). Males perch on shrubs (including larval host plant) often on or near ridges, patrol erratically every few minutes around host plant canopy, in search of females (Scott 1975, 1986).

References
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Citation for data on this website:
Half-moon Hairstreak — Satyrium semiluna.  Montana Field Guide.  Montana Natural Heritage Program.  Retrieved on December 7, 2016, from http://FieldGuide.mt.gov/speciesDetail.aspx?elcode=IILEPD4024