The Grey Copper or Great Copper (Lycaena dione) is a butterfly of the Lycaenidae family. It is found from the southern Prairie Provinces of Canada and western Ontario south to Texas and east to Illinois and Missouri. There is a disjunct population in southern British Columbia. The wingspan is 24–38 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 Rumex crispus and Rumex occidentalis.