The hops blue butterfly (Celastrina humulus) is a rare North American butterfly, found in the Rocky Mountain region of the United States in areas where its host plant, wild hops (Humulus lupulus), grows in abundance. As a member of the Lycaenidae we considered it likely that myrmecophiles may exist with ants found in C. humulus habitats. To better understand the ecology of this species and guide conservation efforts, we investigated and documented myrmecophily with multiple ant species. We found seven ant species with close associations with C. humulus larvae.