Karner blue

The Karner blue (Plebejus samuelis) is an endangered species of small blue butterfly found in some Great Lakes states, small areas of New Jersey, the Capital District region of New York, and southern New Hampshire (where it is the official state butterfly) in the United States. The butterfly, whose life cycle depends on the wild blue lupine flower (Lupinus perennis), was classified as an endangered species in the United States in 1992.

First considered a subspecies of Plebejus melissa, it was first identified and described by novelist Vladimir Nabokov. The name originates from Karner, New York (located half-way between Albany and Schenectady) in the Albany Pine Bush, where it was first discovered. In the novel Pnin, Nabokov describes a score of Karner blues without naming them.

Lupine blooms in late May. There are two generations of Karner blues per year, the first in late May to mid June, the second from mid-July to mid-August.

Local conservation efforts, concentrating on replanting large areas of blue lupine which have been lost to development (and to fire suppression, which destroys the open, sandy habitat required by blue lupine), are having modest success at encouraging the butterfly's repopulation. The Necedah National Wildlife Refuge in central Wisconsin is home to the world's largest population of Karner blues, which benefit from its vast area of savanna and extensive lupine.

In 2003, the Canadian Species at Risk Act listed the Karner blue as being extirpated from Canada. In 2012, after an unusually hot and dry year, the Karner blue was also extirpated in the Indiana Dunes National Park.