The Karner Blue Butterfly is a very small butterfly, about the size of a dime, with a wingspan of only about 1 inch (2.54 cm).
The male has bright, dark blue to silvery-blue wings with a thin black border. The female is less brightly colored, with wings that are a dull blue that often fades to brownish or grayish tones near the edges. Females also have a row of dark spots along the wing edges, each marked with small orange crescents.
On the underside, both males and females are light gray to grayish-brown with rows of small brown spots. Along the outer edges of the wings’ undersides, there is a pattern of blue-green, orange, and black markings that help with camouflage when the butterfly is resting.
The Karner Blue Butterfly is found in dry sandy areas with open woods and clearings such as pine barrens, lakeshore dunes, and sandy pine prairies that contain lots of wild blue lupine.
The larvae of the Karner Blue only eat wild blue lupine. Adult Karner Blue Butterflies eat the nectar of a variety of flowers, including rock cress, raspberry, goldenrod, and butterflyweed.
Two broods of Karner Blue Butterflies hatch each year, one in the spring and one in the summer. After mating, the female Karner Blue lays her eggs on a lupine plant. The eggs are about 0.04 inches (1 mm) in diameter.
When the caterpillars hatch, they are tiny, less than a third of an inch or a few millimeters long. They crawl up the lupine plant and begin to eat the leaves. They eat the leaves of the blue lupine for three to four weeks and then form a chrysalis* and pupate* for 8-11 days.
During pupation, wings, antennae, and legs form, and the caterpillar’s mouth changes to a proboscis – the straw-like extension that butterflies use to suck nectar from flowers.
When the Karner Blue Butterfly emerges, it expands its wings and dries them for about 45 minutes. It then gathers nectar from wildflowers. Karner Blue Butterflies live for only a week or two.
During that time, they mate, and the females lay their eggs on a lupine plant. The eggs from the spring mating will hatch in the summer. This second group of Karner Blue Butterflies mates and lays their eggs on or near a blue lupine plant. These eggs remain dormant until the next spring, when they hatch, and the cycle begins anew.
*A caterpillar pupates when it enters a resting stage called a pupa, where it undergoes a major transformation before emerging as a butterfly.
*A chrysalis is the form a caterpillar takes before it emerges from its cocoon as a fully formed moth or butterfly. The chrysalis has a hard skin that’s left behind after the caterpillar sheds its soft outer skin.
Karner blue butterfly caterpillars have a special relationship with ants. The caterpillars make a sweet liquid that feeds the ants. In return, the ants protect the caterpillars from predators and parasites. Caterpillars with ants are more likely to survive than those without them.
The Karner Blue was first identified as a distinct subspecies of the Melissa Blue Butterfly (Plebejus melissa) in 1944 by novelist and lepidopterist (butterfly expert), Vladimir Nabokov.
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Karner Blue Butterflies are found in the Concord Pine Barrens in East Concord.
For a number of years, biologists have been releasing captive-bred Karner Blues in the hopes that they will begin breeding in the wild.
The Karner Blue Butterfly is the state butterfly of New Hampshire.
The Karner Blue Butterfly could once be found from Maine to Minnesota. Today, its population is limited to Illinois, Indiana, Michigan, Minnesota, New Hampshire, New York, Ohio, Wisconsin, and Ontario in Canada.
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