The Xerces Society for Invertebrate Conservation is an international nonprofit organization that protects the natural world through the conservation of invertebrates and their habitats.Our name (which is pronounced Zer-sees, or /ˈzɚˌsiz/) comes from the now-extinct Xerces blue butterfly (Glaucopsyche xerces), the first butterfly known to go extinct in North America as a result of human activities. The Xerces blue's habitat was destroyed by development in the sand dunes of San Francisco, and the species was declared extinct by the 1940s.