Lycaena cuprea, the lustrous copper, is a butterfly of the family Lycaenidae. It is found in the western mountains of North America. The wingspan is 23–30 mm. Adults are on wing from mid-June to July or August. They feed on the nectar of Cirsium, Medicago sativa and Melilotus species. The larvae feed on Oxyria digyna and Rumex species.