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Montana Field Guide

Montana Field Guides

Gray Hairstreak - Strymon melinus

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; Pyle 2002] Forewing 1.2-1.5 cm. Two-tailed, the lower one longer. Male abdomen pale orange, female abdomen gray. Uppersurface gray with orange spot near tail; undersurface paler gray, hindwing postmedian line often edged inward with orange and outward with white, postmedian line usually relatively straight, orange hindwing marginal spot flat across inward edge and almost reaching postmedian line.

Many flights; spring to fall (Scott 1986). Flies almost all year in the south but mainly March to October elsewhere, May to August at higher elevations and latitudes (Glassberg 2001). Mid-April to October in Colorado (Scott and Scott 1978), late March to mid-October in Oregon and Washington (Pyle 2002; Warren 2005), late April to late August in British Columbia (Guppy and Shepard 2001).

Diagnostic Characteristics
Best determined by uppersurface gray with orange spot near tail, undersurface hindwing postmedian line often edged inward with orange and outward with white, orange hindwing marginal spot flat across inward edge and almost reaching postmedian line.

Species Range
Montana Range Range Descriptions


Range Comments
Across southern Canada south through US and Mexico to northern South America (Scott 1986; Opler and Wright 1999; Glassberg 2001); usually below 2133 m elevation in Colorado but to at least 2926 m (Brown 1957; Scott and Scott 1978; Ferris and Brown 1981), sea level to 2438 m elevation in Oregon (Warren 2005). In Montana, reported throughout the state (Kohler 1980; Stanford and Opler 1993). Common to abundant in Texas and southern California, rare to uncommon elsewhere (Glassberg 2001).

Observations in Montana Natural Heritage Program Database
Number of Observations: 11

(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)


Open weedy areas, grasslands, sagebrush steppe, montane meadows, river basins, agricultural areas (Opler and Wright 1999; Glassberg 2001; Pyle 2002). Habitat in Montana not described but probably similar.

Food Habits
Larval food plants are very diverse, and include Amorpha, Amphicarpa, Asclepias, Astragalus, Callirhoe, Carya, Cassia, Citrus, Comptonia, Crataegus, Croton, Cynoglossum, Desmodium, Diospyros, Echites, Eremocarpus, Eriobotrya, Eriogonum, Fragaria, Glycyrrhiza, Gossypium, Hibiscus, Humulus, Hypericum, Hyptis, Indigofera, Lamium, Lantana, Lespedeza, Lotus, Lupinus, Malus, Malva, Medicago, Melilotus, Mentzelia, Neolloydia, Nolina, Phaseolus, Pinus, Pisum, Polygonum, Porlieria, Quercus, Rhamnus, Rhododendron, Rosa, Rubus, Rumex, Sabal, Salsola, Salvia, Sedum, Sesbania, Sida, Sidalcea, Sphaeralcea, Tecoma, Trifolium, Verbascum, Vicia, Vigna, and Zea (Scott 1986, 1992, 2006; Guppy and Shepard 2001; Warren 2005; James and Nunnallee 2011). Adults feed on flower nectar (including Abronia, Achillea, Aesculus, Agastache, Allium, Apocynum, Arctium, Asclepias, Astragalus, Baccharis, Berberis, Berteroa, Bidens, Boltonia, Buddleia, Carduus, Ceanothus, Centaurea, Cephalanthus, Chrysanthemum, Chrysothamnus, Cirsium, Clematis, Comandra, Conyza, Coreopsis, Croton, Dalea, Echinacea, Erigeron, Eriogonum, Eryngium, Eupatorium, Euphorbia, Geranium, Glycrrhiza, Gutierrezia, Helianthus, Hesperis, Heterotheca, Lesquerella, Liatris, Linaria, Marrubium, Medicago, Melilotus, Mentha, Oxytropis, Phacelia, Phlox, Plantago, Polygonum, Prunus, Psoralea, Pycnanthemum, Ratibida, Rhus, Rudbeckia, Salix, Senecio, Solidago, Sphaeralcea, Symphyotrichum, Taraxacum, Thelesperma, Trifolium, Verbascum, Verbena, Verbesina, Viguiera, Zinia) and mud (Tooker et al. 2002; Scott 2014).

Reproductive Characteristics
Females lay eggs singly on host plant inflorescences, flower buds, fruits, small leaves near flowers, seeds (Scott 1986, 1992, 2006). Eggs hatch in captivity in about 3 days, larvae develop to L4 instars in about 24 days post egg-hatch (depending on temperature), pupate in another 3-4 days, adults eclose (emerge from pupae) in about 7-10 days after pupation. Larvae feed on flowers and frots, build no nest, associate with ants, pupate in sheltered location like curled leaf, overwinter as pupa (Scott 1979, 1986; James and Nunnallee 2011). Males perch on small hilltop trees or shrubs, usually late morning through afternoon, waiting for passing females (Scott 1975b, 1982, 1986).

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Citation for data on this website:
Gray Hairstreak — Strymon melinus.  Montana Field Guide.  .  Retrieved on , from