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Montana Field Guide

Montana Field Guides

Juniper Hairstreak - Callophrys gryneus

Native Species

Global Rank: G5
State Rank: S4

Agency Status

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General Description
[From Ferris and Brown 1981; Scott 1986; Opler and Wright 1999; Glasberg 2001; Pyle 2002] Forewing 1.2-1.3 cm. Tailed. Uppersurface gray to reddish-brown, redder near tails, forewing with postmedian row of white spots in alignment, hindwing apple green to yellow-green; hindwing undersurface postmedian white line irregular and edged inwardly with red-brown, strong marginal blue and black spots in tail area.

Two flights, late April to early June and late June to early August in northeast and Midwest; several flights southward; one flight, mostly mid-May to June in most of west, April to May on Pacific Coast (Scott 1986). Two flights in south and east, March to May and June to September; one flight in much of the west, mainly late May to early July (Glassberg 2001). Late April to August in Colorado (Scott and Scott 1978), late March to early August in Oregon and Washington (Pyle 2002), early May to late June in British Columbia (Guppy and Shepard 2001).

Diagnostic Characteristics
Best determined by association with junipers, the hindwing uppersurface apple green to yellow-green; hindwing undersurface postmedian white line irregular and edged inwardly with red-brown, strong marginal blue and black spots in tail area.

Species Range
Montana Range Range Descriptions


Range Comments
Southern British Columbia south to southern California and northwestern Mexico, east to southern Ontario, New England and most of eastern US to northern Louisiana and Florida (Scott 1986; Opler and Wright 1999; Glassberg 2001; Pyle 2002); 1463 m to 2682 m elevation in Colorado (Scott and Scott 1978), 1830 m to 2135 m elevation in the Rocky Mountain states (Ferris and Brown 1981), 549 m to 1463 m elevation in Oregon (Warren 2005). In Montana, reported from across most of the state except the upper northwest counties (Kohler 1980; Stanford and Opler 1993). Taxonomy remains unstable and confusing, compounded by unintended introductions on host plants used in ornamental plantings (Johnson 1978). Uncommon to common (Glassberg 2001).

Observations in Montana Natural Heritage Program Database
Number of Observations: 2

(Click on the following maps and charts to see full sized version) Map Help and Descriptions
Relative Density



(Observations spanning multiple months or years are excluded from time charts)

Non-migratory; adults may stray up to 15 km from host junipers (Scott 1986).

Pinyon-juniper woodland, juniper forest, juniper windbreaks, juniper shrub-steppe, city parks and gardens (Scott 1986; Opler and Wright 1999; Glassberg 2001; Pyle 2002). Habitat in Montana not described but probably similar.

Food Habits
Larval food plants include multiple species of Juniperus (Johnson 1978; Ferris and Brown 1981; Scott 1986, 1992; Guppy and Shepard 2001; Pyle 2002). Adults feed on flower nectar (including Achillea, Aletes, Apocynum, Asclepias, Astragalus, Baccharis, Ceanothus, Chrysothamnus, Cirsium, Cleome, Comandra, Conium, Cryptantha, Eriogonum, Erysimum, Euphorbia, Geranium, Harbouria, Heterotheca, Hymenopappus, Jamesia, Melilotus, Mimulus, Opuntia, Phacelia, Phlox, Physocarpus, Potentilla, Prunus, Rhus, Rubus, Rudbeckia, Salix, Schoenocrambe, Sedum, Senecio, Solidago, Trifolium, Veronica) and mud (Scott 2014).

Reproductive Characteristics
Females lay eggs singly on host plant foliage tips and flowering twigs (Scott 1986; Pyle 2002). Eggs hatch in about 8-10 days, develop to L4 instar and pupation in about 30 days post-hatch (depending on temperature). Larvae are solitary, feed on juniper needles, build no nest, depart host plant as mature larvae prior to pupation, pupate in litter, overwinter (hibernate) as pupae (Scott 1979; James and Nunnallee 2011). Males perch throughout the day on the tops and sides of juniper trees, more often on ridge crests than in valleys, to await passage of females (Scott 1975b, 1986).

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Citation for data on this website:
Juniper Hairstreak — Callophrys gryneus.  Montana Field Guide.  .  Retrieved on , from