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Threats
Urbanization,
herbicides, declining
frequency of wildfires
STATUS:
ESA -- ENDANGERED
SIZE:
Wingspan:
0.9-1.25 inches
(2.3-3.2 cm), about
the size of a quarter
POPULATION:
Unknown but
drastically declining
CURRENT RANGE:
New York, New Hampshire, Wisconsin, Illinois, Indiana, Michigan, Minnesota
CONSERVATION:
Captive-breeding and
release programs;
preservation of natural habitat and host plants
In 1977, the Karner blue became the first insect
to be listed on the New York State Endangered Species List.
In the Concord Pine Barrens of New Hampshire (the only area in New England that still has Karner blues), an ambitious program of habitat improvement and wild lupine planting began in 1994. In New York, a fire-management plan has been proposed for a 2.4 square mile (6.2 sq km) preserve within the Albany Pine Bush, where huge populations of Karner blues once thrived.
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Wildfires and Butterflies
The small blue flower of the wild lupine (Lupinus perennis) blooms in pine and oak barrens of the Northeast and Midwest. A member of the pea family, it is the only known food source of the larvae of the Karner blue butterfly. Without this plant, the butterfly cannot exist.
Wild lupine does best in sandy soils, in areas that are occasionally razed by wildfires. Fire helps keep shrubs low and purges the area of more aggressive colonizers -- plants like aspen, maple, and black locust that, if they took hold, would shade out the lupine and other smaller plants. Karner blues rely on lupine for their whole life cycle. In April, tiny butterfly eggs hatch after spending the winter attached to the lupine stems. The newly born caterpillars feed avidly on the lupine's newly sprouted spring leaves. The caterpillars pupate in May and emerge as adults at the end of the month. In June, these first-brood females lay their eggs, again on the lupine stems, and a second brood of larvae hatch about a week later. These caterpillars become second-brood adults by mid-July. They lay eggs on litter and lupine stems that will hatch the following spring.
Recently this cycle has been severely interrupted in various parts of the U.S. In the Northeast, wildfires have been dramatically reduced by human intervention. Without fires to clear away competitors, lupine has nearly disappeared. The plant is also controlled with pesticides along power line and highway right-of-ways. For the Karner blue, the result is devastation: its numbers have dropped by 99 percent in the last two decades.
Novelist and amateur
lepidopterist Vladimir Nabokov named the Karner blue, and also designated the place where the butterfly was first described -- Karner,
a village
in upstate
New York.
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