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Karner Blue Butterfly © Bill Daunis

The Karner blue butterfly is listed as "Endangered" by the U.S. government.

Small Butterfly Endangered from Habitat Loss and Degradation

A subspecies of the Melissa blue butterfly, the Karner blue is a relatively small butterfly, averaging around one inch in wingspan. Males’ wings across the top are silvery blue to dark blue with narrow black margins; females are graying brown with bands of orange inside the blade border. Found around the Great Lakes and the northeast United States, the Karner blue typically inhabits semi-shaded areas with sandy soil. It is a fairly sedentary creature, rarely venturing farther than 300-600 feet from its hatching place.

There are two broods each year of the Karner blue butterfly. The first winters as eggs, hatching in April and emerging at the end of May and June. Adults are in flight the first 10-15 days of June. Then they lay eggs, which hatch about a week later and feed as larvae for three weeks before flying as adults into mid-August.

The second brood hatches the following spring. Individual adults usually live only five days or so, though some females live as long as two weeks. Larvae feed only on the wild lupine plant and are tended by ants, which feed on a liquid it secretes.

The Karner blue butterfly experienced drastic declines in the 1970s and 1980s. It is now believed to be extirpated in Illinois, Iowa, Pennsylvania, Maine and New Hampshire, and in the Canadian province Ontario. It is listed as "Endangered" by the U.S. government. The main threat to the species has been habitat loss and degradation. Because the larvae feed only on wild lupine, habitats are also lost to succession, the lupine being eventually shaded out by pines, oak and shrubby vegetation.