Karner blue (Plebejus melissa samuelis)

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Karner blue

Plebejus melissa samuelis

Butterfly

Small blue butterfly of oak savannas and pine barrens whose larvae feed exclusively on wild lupine (Lupinus perennis) — the only plant the caterpillars can eat. Two broods are produced each year, both tied to lupine bloom and regrowth, and the larvae are tended by ants in a facultative mutualism. Adults nectar on a range of open-habitat wildflowers, but the obligate dependence on wild lupine makes the butterfly a textbook case for why a single native host plant can be load-bearing for an entire species.

Conservation

Listed as Endangered under the U.S. Endangered Species Act in 1992 (USFWS). Included in the Xerces Society's Red List of pollinator insects of North America. Habitat loss and the suppression of the periodic fire and disturbance that maintain open lupine-rich savanna are the central drivers of decline; reintroductions are underway in several states.

Plants in the catalog

Larval host plants · 1

Wild lupine

Lupinus perennis

Specialist

Range

Historically ranged across roughly a dozen northern states from Minnesota to the Atlantic coast plus Ontario. Now restricted to scattered populations in the Great Lakes region and Northeast — chiefly Wisconsin, Michigan, New York, and New Hampshire, with reintroductions in Ohio, Indiana, and elsewhere.

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