The western tailed-blue (Cupido amyntula) is a Nearctic non-migratory butterfly that commonly takes flight during the spring and summer seasons of March–July.

[1] Adults feed on various things such as flower nectar, horse and coyote manure, urine, and mud.

Within these locations, adult C. amynula visits white, purplish, yellow, or pinkish flowers, including Sedum lanceolatum and Astragalus flexuosus.

This species also occurs along weedy forest margins across Canada, as far as eastern Quebec, New Brunswick, and Maine.

[9] Male C. amyntula typically perches and patrols between shrubs, hillsides, and gully mouths throughout the day in search of a receptive female to mate with.