Plebejus melissa samuelis Nabokov, 1944
Lycaeides melissa samuelis
Basis for Listing
The historical range of the Karner blue forms a narrow band from Maine and New Jersey westward through the southern Great Lakes region to eastern Minnesota and northeastern Iowa (Dirig 1994). It was always a highly local species because of the naturally patchy distribution of its specialized habitat, sandy barrens and savannas where its obligate larval host plant, wild blue lupine (Lupinus perennis), occurs. Human land use has had a severe impact on this habitat, resulting in the disappearance of many colonies and the reduction of most others to precariously small numbers of adult butterflies. The Karner blue is believed to be extirpated in several states and the Province of Ontario, and is barely hanging on in several others (NatureServe 2008). Only in Wisconsin are there still numerous colonies, including several sizeable metapopulations (Bleser 1994).
The Karner blue is a typical member of the subfamily of the Lycaenidae commonly known as blues because of the blue coloration of the upper wing surfaces in males (females usually are more brown than blue). It is a small butterfly (forewing length 1.2-1.5 cm (0.47-0.59 in.) from base to apex) with rounded wings. Males and females are nearly identical in size and shape. The dorsal surfaces of both hind and forewings of males are bright, violet- or lilac-tinged blue, with a slight frosting of whiter scales in fresh individuals, especially along the veins. There is a thin black line along the outer edge of the wings, and a contrasting fringe of long, white scales. The thorax above is clothed in a dense pile of blue hairlike scales. The female is mostly dark brown above, with blue scaling confined to the basal area of the wings. There is a row of circular black spots near the outer margin of the hind wing that are capped on their inner sides with bright orange crescents. Beneath, the sexes are nearly identical, with a sparse pattern of white-ringed black spots on a pale gray ground (sometimes darker gray in females). Near the outer margin of the hind wing there is a band of prominent, bright orange crescents each enfolding a silvery-blue eye and thinly capped on the inner edge with black. Smaller orange spots without the silvery inclusions continue the band along the forewing.
Minnesota's only surviving occurrence of the Karner Blue butterfly is in a mosaic of oak savanna and sand barrens habitats in the southeast, where wild blue lupine is common. The extirpated colony was concentrated along an unpaved township road through an overgrown sand savanna. Although wild blue lupine plants could still be found in the overgrown savannah away from the road, the butterfly utilized primarily a small population of vigorous plants along the road edges (Lane and Dana 1994). Similar habitats are reported for Wisconsin and Michigan (Swengel and Swengel 1997; Nielsen 1999).
Biology / Life History
The Karner blue has two generations each year throughout its range, including Minnesota. Eggs laid by the second generation females overwinter and hatch early in the spring. Although the eggs are laid on various plant surfaces near the bases of wild blue lupine plants, the tiny hatchling larvae have to find their way to lupine shoots emerging from the soil. The first generation adults can begin to appear in mid-May and are mostly gone by late June. Year-to-year variation in the rate of warm-up can advance or retard the flight period. Females of the first generation lay their eggs on lupine stems and leaves. Second generation adults emerge and fly beginning as early as mid-July and continuing into late August. Adult life expectancy in the wild is estimated to be only a few days. There is no information on how many eggs a female will lay over her lifetime.
Conservation / Management
The small size of Minnesota's only known colony is the primary threat facing the Karner blue in the state. Such a small, isolated colony is at high risk of extirpation resulting from both natural events (such as severe drought or hailstorms) and human caused ones (such as insecticide application), as well as from the vagaries of normal population processes (for example, by chance all adults in one generation are males). Loss of genetic diversity in a small population is another possible threat. The Minnesota colony is at least 80 km (48 mi.) from the nearest known occurrences in Wisconsin (Eau Claire and Jackson counties), making it unlikely that immigration from the Wisconsin population will maintain genetic diversity.
Conservation Efforts in Minnesota
In September 2003, the U.S. Fish and Wildlife Service completed a national Karner blue butterfly recovery plan. The objective of the plan is to restore viable metapopulations of Karner blues across the species extant range so that it can be reclassified from endangered to threatened, and eventually removed from the federal endangered species list altogether.
Bleser, C. A. 1994. Karner Blue Butterfly survey, management and monitoring activities in Wisconsin: 1990-Spring 1992. Pages 153-162 in D. A. Andow, R. J. Baker, and C. P. Lane, editors. Karner Blue Butterfly: a symbol of a vanishing landscape. Miscellaneous Publication 84-1994, Minnesota Agricultural Experiment Station, University of Minnesota, St. Paul, Minnesota.
Cuthrell, D. L. 1990. Status of the Karner Blue Butterfly, Lycaeides melissa samuelis Nabokov, in Minnesota 1990. Report submitted to the Nongame Wildlife Program, Minnesota Department of Natural Resources. 44 pp. + appendix.
Dirig, R. 1994. Historical notes on Wild Lupine and the Karner Blue Butterfly at the Albany Pine Bush, New York. Pages 23-36 in D. A. Andow, R. J. Baker, and C. P. Lane, editors. Karner Blue Butterfly: a symbol of a vanishing landscape. Miscellaneous Publication 84-1994, Minnesota Agricultural Experiment Station, University of Minnesota, St. Paul, Minnesota.
Herms, C. P., D. G. McCullough, L. S. Bauer, R. A. Haack, D. L. Miller, and N. R. Dubois. 1997. Susceptibility of the endangered Karner Blue Butterfly (Lepidoptera: Lycaenidae) to Bacillus thuringiensis var. kurstaki used for gypsy moth suppression in Michigan. The Great Lakes Entomologist 30:125-141.
Lane, C., and R. Dana. 1994. The status of the Karner Blue Butterfly in Minnesota. Pages 113-122 in D. A. Andow, R. J. Baker, and C. P. Lane, editors. Karner Blue Butterfly: a symbol of a vanishing landscape. Miscellaneous Publication 84-1994, Minnesota Agricultural Experiment Station, University of Minnesota, St. Paul, Minnesota.
Lane, C. P. 1999. Benefits of heterogeneous habitat: oviposition preference and immature performance of Lycaeides melissa samuelis Nabokov (Lepidoptera: Lycaenidae). Dissertation, University of Minnesota, St. Paul, Minnesota. 185 pp.
Malicky, H. 1970. New aspects on the association between lycaenid larvae (Lycaenidae) and ants (Formicidae, Hymenoptera). Journal of the Lepidopterists' Society 24:190-202.
NatureServe. 2008. NatureServe Explorer: An online encyclopedia of life [web application]. Version 7.0. NatureServe, Arlington, Virginia.
Nice, C. C., G. Gelembiuk, N. Anthony, and R. ffrench-Constant. 2000. Population genetics and phylogeography of the butterfly genus Lycaeides. April 21, 2000 report to U.S. Fish and Wildlife Service, Fort Snelling, Minnesota. 43 pp.
Nielsen, M. C. 1999. Michigan butterflies and skippers: a field guide and reference. Michigan State University Extension, East Lansing, Michigan. 248 pp.
Packer, L., J. S. Taylor, D. A. Savignano, C. A. Bleser, C. P. Lane, and L. A. Sommers. 1998. Population biology of an endangered butterfly, Lycaeides melissa samuelis (Lepidoptera: Lycaenidae): genetic variation, gene flow, and taxonomic status. Canadian Journal of Zoology 76:320-329.
Savignano, D. A. 1994. Benefits to Karner Blue Butterfly larvae from association with ants. Pages 37-46 in D. A. Andow, R. J. Baker, and C. P. Lane, editors. Karner Blue Butterfly: a symbol of a vanishing landscape. Miscellaneous Publication 84-1994, Minnesota Agricultural Experiment Station, University of Minnesota, St. Paul, Minnesota.
Swengel, A. B. 1994. Observations on the effects of fire on Karner Blue Butterflies. Pages 37-46 in D. A. Andow, R. J. Baker, and C. P. Lane, editors. Karner Blue Butterfly: a symbol of a vanishing landscape. Miscellaneous Publication 84-1994, Minnesota Agricultural Experiment Station, University of Minnesota, St. Paul, Minnesota.
Swengel, A. B., and S. R. Swengel. 1997. Co-occurrence of prairie and barrens butterflies: applications to ecosystem conservation. Journal of Insect Conservation 1:131-144.
U.S. Fish and Wildlife Service. 2003. Final Recovery Plan for the Karner Blue Butterfly (Lycaeides melissa samuelis). U.S. Fish and Wildlife Service, Fort Snelling, Minnesota. 273 pp.