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Montana Field Guide

Montana Field Guides

Acadian Hairstreak - Satyrium acadica

Native Species

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] Forewing 1.5-1.7 cm. Tailed. Uppersurface gray with one orange spot on hindwing opposite tail; undersurface gray with row of submarginal orange spots capped with black, hindwing with postmedian row of fairly uniform round black spots, blue tail-spot capped with orange, black bar above tail spot often sharply angled.

One flight; late June to early August (Scott 1986). Mid-June to August (Glassberg 2001). Early July to early August in Colorado (Scott and Scott 1978), late June to early September in British Columbia if correctly identified (Threatful 1988).

Diagnostic Characteristics
Best determined by a combination of undersurface gray with row of submarginal orange spots capped with black, blue tail-spot capped with orange.

Species Range
Montana Range Range Descriptions


Range Comments
Extreme southeastern British Columbia, northern Idaho, western Montana east across southern Canada and adjacent US to Nova Scotia and New England, south to Colorado in the west, New Jersey and Maryland in the east (Scott 1986; Opler and Wright 1999). Although reported as common in parts of southeastern British Columbia (Threatful 1988), other authorities state that the species has not been reported in British Columbia, northern Idaho, or anywhere else west of south-central Montana since 1920 (Pyle 2002); to 2560 m elevation in Colorado but typically 1830 m or below (Brown 1957; Scott and Scott 1978). In Montana, reported from several south-central and eastern counties (Kohler 1980; Stanford and Opler 1993). Locally uncommon to locally common (Glassberg 2001).


Riparian woodland, stream courses, marshes, willow thickets (Opler and Wright 1999; Glassberg 2001). Willows and along streams in Greater Yellowstone Ecosystem (Debinski and Pritchard 2002).

Food Habits
Larval food plants include several species of Salix (Scott 1986, 1992). Adults feed on flower nectar, including Apocynum, Asclepias, Ceanothus, Cirsium, Medicago, Melilotus, Polygonum, and Tamarix (Scott 1986, 2014; Tooker et al. 2002).

Reproductive Characteristics
Females lay eggs in small numbers (1-6 eggs per oviposition) on host plant twig usually in a small hole, less often at base of leaf, then sealed with a "glue window." Overwinter (diapause) as egg; larvae build no nests, associate with ants. (Scott 1979, 1986, 1992). Males perch (infrequently patrol) on small willows or other plants less than 1 m above the ground during the afternoon waiting for females (Scott 1975b, 1986).

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Citation for data on this website:
Acadian Hairstreak — Satyrium acadica.  Montana Field Guide.  .  Retrieved on , from