Abstract

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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.

Abstract:

A status survey for the Karner Blue butterfly (Lycaeides melissa samuelis) was conducted during the late spring and summer of 1990. This butterfly, which appears to be declining across much of it's range, is proposed for federal listing and status reports in the midwest are lacking.

The Karner Blue overwinters as ova laid on or very near wild lupine (Lupinus perennis) by second brood females. The eggs hatch in early spring and the larvae feed on the lupine leaves for about three weeks. Just before pupating the larvae moves off the plant among the litter. Typically the first brood adult flight period is from late May to mid-June. In Minnesota the second adult flight period is from late July to mid-August. Adults on the average live for only 5 days. Adult females usually oviposit on the lupine plant itself or very near the plant on grass or sedge blades, or in the duff. Thus, no stage in the butterflies life cycle would be highly resistant to fire.

The goals of this survey were to: (1) identify known locations or probable locations of large populations of wild lupine (Lupinus perennis), the Karner Blue butterfly's exclusive host plant, (2) survey these identified sites to confirm the presence of the host plant and to search the site for the Karner Blue butterfly, and (3) to provide baseline data on the status of the butterfly and it's host plant in Minnesota.

The survey was conducted in two phases. The first phase consisted of analyzing aerial photos, soil maps, and topographical maps to identify habitat suitable for lupine, and conducting field work in search of the plant and possible first brood butterflies. The second phase included rechecking sites that contained lupine for second brood adult Karner Blue butterflies.

Although this survey found populations of lupine in each study area, it was less common in Minnesota than had been believed. Large populations of the plant were found within the Whitewater Wildlife Management Area, (WMA) in Winona County, the Himlie Sand Barrens site in Fillmore County, Sherburne National Wildlife Refuge in Sherburne County, and within the St. Croix Wild River State Park in Chisago County.

Fourteen sites out of 50 contained lupine; of those sites many populations are in a precarious state. Fire supression appears to be the main reason that suitable habitat is limited in the oak barrens region. It is the author's opinion that wild lupine should be listed as a species of "special concern" in Minnesota.

There were two historical records of the Karner Blue butterfly in Minnesota. The insect had not been found at either of these sites since 1984 and was believed to be extirpated from the state. However, a population was found within the Whitewater WMA in Winona County during this 1990 survey. Because the Karner Blue butterfly was found at only two locations, both within one WMA, it should be listed as an "endangered" species in Minnesota. An estimate of the population size was beyond the scope of this study. This should, however, be a top priority in future Minnesota studies on the Karner Blue. It is essential to understand the total habitat requirements of the butterfly in order to manage the area in such a way as to insure the survival of the species.

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