Karner Blue

The Karner blue (Plebejus samuelis) is a small blue butterfly native to the Great Lakes region and northeastern North America. It is closely associated with oak savanna and pine barrens habitats because its larvae feed exclusively on wild lupine (Lupinus perennis). The species once occurred in a narrow, nearly continuous band across twelve U.S. states and southern Ontario, Canada. The United States Fish and Wildlife Service currently identifies surviving populations in portions of Wisconsin, Michigan, New York, New Hampshire, and Ohio.

The butterfly has undergone extensive range contraction caused principally by habitat loss, fragmentation, and the ecological succession of formerly open savanna and barrens habitat. Fire suppression has contributed to this process by allowing shrubs and trees to shade out wild lupine and flowering plants required by the butterfly.

The Karner blue was listed as endangered under the United States Endangered Species Act on 14 December 1992. It is the official state butterfly of New Hampshire, designated the same year under RSA 3:18.

In Canada, the butterfly has not been reported since 1991 and is considered extirpated. The Committee on the Status of Endangered Wildlife in Canada designated it extirpated in April 1997, and confirmed that status in 2000, 2010, and 2019.