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The Karner blue butterfly is a small butterfly with a wingspan of about one inch and the sexes are different in appearance. The upper side of the male's wings are violet blue with black margins and white fringed edges. The upper side of the females' wings range in color from bright purplish blue near the body to dark gray-brown with orange crescents on the edges of the hind (back) wings. The underside of both sexes is gray to fawn colored with orange crescents and metallic spots on both the hind and fore wings.
Karner blue butterflies live in areas described as oak savannas and pine barren ecosystems. These ecosystems are likely to contain many different herbaceous plants and grasses with scattered small groves of trees and shrubs. The open sunny nature of these systems creates the right conditions for wild lupine, a plant that the Karner blue caterpillar depends on. Wild lupine is the only plant that the caterpillar is known to feed on and therefore critical to survival of the butterfly. Adult Karner blues feed on nectar from a variety of wild flowers like the horsemint, butterflyweed, and bachelors button.
Historically, wildfires and grazing created and maintained savanna and barrens ecosystems. Wildfires would kill, or set back, trees and shrubs, letting sunlight onto the forest floor, creating grassy areas. These conditions would remain until shrubs would start invading the grasslands, eventually shading out the grasses and herbs and creating a forest. Historically, any one site did not remain as Karner blue habitat. Instead, intermittent wild fires created a constantly changing patchwork of these grassy openings across the landscape. Karners can fly up to about 1.4 miles across open landscapes. So as a savanna began to be overtaken by trees and shrubs, the butterflies would disperse to nearby openings that may have been recently created by wildfire or were being maintained by grazing mammals such as bison.
Today, wildfires are practically nonexistent. The disturbance that wildfires once created is now sometimes replicated by logging practices or mowing along power lines and roadways where the rights-of-way are kept clear of trees and shrubs. On some public lands, land managers use timber harvests, mowing, grazing, herbicides, and controlled burns to manage for oak savannas or pine barrens.
The savanna and barrens ecosystems that support Karner blue butterflies are almost as rare as the butterfly itself. There are also many other plant and animal species that use these ecosystems for all or part of their life cycle. The rarest of these include: in the eastern United States, the Persius duskywing (Erynnis persius) and the frosted elfin (Incisalia irus). These are butterflies that also depend on the wild lupine of the pine barrens and oak savanna ecosystems. In Indiana, Minnesota, Wisconsin, and Michigan savannas and/or barrens provide habitat for the phlox moth, eastern massasauga rattlesnake, Blanding's turtle, loggerhead shrike, and prairie fame flower, all of which appear to be species with declining numbers.
The Karner blue requires wild lupine (Lupinus perennis), the only plant its caterpillar is known to feed on and therefore critical to the butterfly's survival. The Karner blue usually lays two batches of eggs each year. Eggs laid the previous summer hatch during mid-April when the lupine are first coming up. The caterpillars feed on wild lupine leaves and are commonly tended by ants. It appears the ants protect the caterpillars from some natural enemies and that the ants in return collect a nectar from the caterpillar. Once mature, the caterpillars form a cocoon around themselves; this happens about the end of May or early June. Within about two weeks the adult butterflies emerge from their cocoon and begin laying eggs on the lupine plants.
These eggs hatch, the caterpillar feeds on the lupine, matures, then forms a cocoon; adults again emerge in July. By the time that these butterflies are ready to lay eggs, many of the lupine plants have died back and eggs are laid on old lupine stems, on plant litter, and on grass blades near wild lupine. By the end of August or early September all adult butterflies have died. Their eggs overwinter and do not hatch until the following spring.
Because their eggs fall to the ground or are laid on leaf litter, or on stems of lupine or grasses that fall to the ground, it is the winter snows that protect the eggs from freezing temperatures and from dehydration. The range of Karner blues only overlaps with the range of wild lupine where there are long periods of winter snowpack. Wild lupine is found in far more areas than Karner blues; its range extends across the Great Lakes states and down the east coast to Florida.
Adult Karners feed on nectar from many different wildflower species, but because the caterpillar can only successfully feed on wild lupine, the reproductive success of Karner blue butterflies is critically dependent on the wild lupine.
Karner blue butterflies once occurred in a nearly continuous narrow band across twelve states and the province of Ontario, Canada, but it has been eliminated from at least five of those states and Ontario. Today it is found in portions of New Hampshire, New York, Michigan, Wisconsin, Ohio, Indiana, and Minnesota. Over the past century, the number of Karner blue butterflies has declined by at least 99 percent across their historic range.
Small remnant populations (and a few larger populations) remain in Minnesota, New York, New Hampshire, Indiana, and Ohio. Reintroduction programs are ongoing in Ohio, New Hampshire, and Indiana with the goal of establishing healthy populations of the butterfly in those states. Wisconsin and Michigan lie in the heart of Karner range where Karner blue butterfly sites are more numerous but still require management and restoration to restore and maintain viable populations of the species.
The single most important factor causing the decline of the Karner blue butterfly across its range has been the loss of habitat due to suppression of wild fires, clearing land for farming, and developing land for commercial and residential purposes. Without disturbance activities such as fire and grazing, shrubs and trees invade the open savanna and barrens and shade out the grass and herbaceous plants, including wild lupine. When this happens, only pockets of grassy areas remain, making it hard for butterflies to find more areas with wild lupine, and limiting the amount of habitat available. This results in small isolated populations of Karner blue butterflies. The Karner blue butterfly's habitat is very specific, and the butterfly is unable to adapt to these changes in its environment. Habitat loss, isolation of populations, combined with the extremely small size of many of the remaining population, puts these populations at high risk of "winking out."
The Karner blue habitat in the Albany Pine Bush, which once covered as much as 40,00 continuous acres, has been reduced to 2,000 acres. These 2,000 acres are dissected by barriers to butterfly dispersal such as roads and buildings and are subject to disturbance by off-road vehicles and horseback riding. The pine barrens in New Hampshire have largely been destroyed as a result of industrial, commercial, and residential development; road and airport construction; and gravel and sand mining. In Wisconsin, remaining habitat is threatened by encroachment of nearby forests, conversion of barrens to pine plantation, and commercial and urban development. Development and agricultural land conversions have been a major contributor to the habitat loss in Michigan.
Management for Karner blue butterflies in most cases means management for the oak savanna and pine barrens ecosystem. In some cases it is hoped that recovery can be realized on lands managed for other purposes such as non-intensive forestry operations or military operations such as those conducted at Fort McCoy in Wisconsin.
Savanna and barrens ecosystems are as imperiled as the butterfly. Restoration and protection of savannas will lead to the recovery of Karner blues. So synonymous are Karner blue and savanna management that Necedah National Wildlife Refuge has a savanna restoration and management plan instead of a Karner blue management plan. The result of their plan has been the establishment of a large viable population of Karners and progress towards recovery of the species.
Wisconsin, the state with the greatest number of butterfly sites, developed a Karner Blue Butterfly State-wide Habitat Conservation Plan (HCP). As of 2006, there are 40 partners in the HCP, with the Wisconsin Department of Natural Resources being one of the major partners and lead in this effort. Other partners include major forestry stakeholders, conservation organizations, county forest departments, utility companies, private landowners, The Nature Conservancy, and the Wisconsin Departments of Agriculture and Transportation. This plan was developed to ensure that management and restoration of Karner blue habitat continues even though some habitat may be destroyed or degraded by partner activities.
To ensure conservation of the Karner blue, all partners plan to incorporate conservation measures for the butterfly into their land management activities (e.g. the use of herbicides in forestry operations will be adjusted to enhance the growth of wild lupine). The partners are also developing an outreach and education strategy to further conservation of the butterfly and its habitat on other private lands in Wisconsin.
In other States, protection and restoration of savannas is occurring on many public lands, both Federal and State. And interested private landowners are providing savanna habitat for Karner blues. The Huron-Manistee National Forest and the Michigan DNR are playing major roles in habitat restoration in Michigan as is the National Park Service's Indiana Dunes National Lakeshore and TNC in Indiana. Habitat restoration efforts are ongoing on state property in Minnesota and on TNC, state, and private property in New York. The U.S. Fish and Wildlife Service and a host of other public and non-governmental conservation organizations, most notably the New Hampshire Fish and Game Department, have undertaken significant protection and enhancement efforts in New Hampshire. The Karner blue has been designated the official butterfly of the City of Concord as well as the state of New Hampshire.
The U.S. Fish and Wildlife Service prepared a Karner Blue Butterfly Recovery Plan that outlines a strategy for recovering the butterfly range-wide. It identifies tasks to restore habitat and stabilize and recover Karner blue populations. The Recovery Plan was published in 2003 and is available online (1.6MB, 293 pages).
Since the landing of the Pilgrims in 1620, more than 500 species, subspecies, and varieties of our Nation's plants and animals are known to have become extinct. In contrast, during the Pleistocene Ice Age, all of North America lost only about three species every 100 years. This recent, catastrophic loss of biological diversity is continuing at an unprecedented rate. Each and every species has a valuable ecological role in the balance of nature and each loss destabilizes that fragile balance. Once a species is extinct, it is lost forever.Experience has proven that many plants and animals have properties which will prove beneficial to humans as sources of food and medicine. With the loss of each species, we lose a potential resource for improving the quality of life for all humanity.
Karner blue butterflies are endangered primarily because the savanna and barrens ecosystems that they depend on for survival are also endangered. Recovering the Karner means recovering these unique and interesting ecosystems. Restoring these systems will not only result in recovery of Karner blue populations, but will also help stabilize and enhance the populations of many other species of plants and animals that depend on these ecosystems for survival.
Article revised November 2006
Last updated: July 19, 2016