Size: 1.0 - 1.25 inches wingspan
Key ID features: Both sexes dull gray above and below. Below, median band of small dark spots with white halos, and submarginal band of black spots with halos. No tails.
Similar species: May be confused with a female Boisduval's blue, which has some blue below (Half-moon has no blue), white fringes, and usually one to three black basal spots on HW below. Range does not overlap with closely related Sooty Hairstreak.
Host plant: Lupines (Lupinus).
Habitat: Subalpine meadows, high ridges, sage steppe, open slopes.
Range: East of the Cascades except Columbia basin in Gilliam, Morrow and Umatilla counties.
Season: Mid-May to early September
Conservation Status: Secure