Labrador Sulphur (Colias nastes Boisduval)
Wing span: 1 1/4 - 1 3/4 inches (2.8 - 4.3 cm).
Identification: Upperside of male pale, washed-out green-yellow with a diffuse dark outer band; female usually a dull white; both male and female with enclosed lighter spots, although the spots are much more distinct in males than females; hindwing below with discal dot narrly edged with pink and stretched outwardly; female hindwing above with a light streak in the discal cell.
Life history: Caterpillar dark green with lateral pink-edged stripes. Adults fly rapidly and very erratically over the tundra, dropping between rocks to hide.
Flight: One flight from mid-June to mid-September.
Caterpillar hosts: Plants in the pea family (Fabaceae) including showy locoweed.
Habitat: Arctic and alpine tundra.
Range: Restricted to the tundra and alpine zones stretching from northern and western Alaska across northern Northwest Territories and the arctic islands, southward through British Columbia to northern Washington and northern Montana.
