Milwaukee Public Museum

by Susan Borkin

EDITOR'S NOTE: This article is reprinted from LORE magazine (vol. 43, no. 2 (June, 1993), p. 16-19), an MPM publication that is a benefit of museum membership. ©1996 Milwaukee Public Museum, Inc.

The great copper, Lycaena xanthoides dione, is one of several butterflies currently under study, with my goal being to uncover the details of their natural history and understand what is required for their survival.

The great copper is the largest of the six butterfly species commonly called coppers that are found in Wisconsin. It has a wingspan measuring about one and one-half inches, and its coloration is mousey gray above and white beneath, with black spots and a variable amount of orange along the hindwing margins. Generally, it is characterized as being a highly localized and uncommon resident of the state.

In 1976, about a year after I started working at the museum, I collected a single great copper along an unmowed section of one of the county parkways. I grew up close to this site and my father still lives in his original home nearby. I witnessed many changes there over the years, construction of the interstate which bisects the site, rechanneling the small creek that once teamed with life into a wide algae-coated concrete ditch, and the progression of shrubby willows and sea of reed canary grass where there had been a wet sedge meadow complete with its chorus of spring peepers. I don't recall seeing the great coppers there during my childhood, but then they are far less conspicuous than the bright orange and black monarchs or irridescent red-spotted purple butterflies I can recall. I collected a second great copper at the site one year later almost to the day, but never encountered the species at other sites I visited in the state.

The two specimens were placed together with the only great copper I found already in the museum collection. It had been collected somewhere in Cudahy, Wisconsin in 1938. I started to compile literature, search for old records, and talk to other Wisconsin lepidopterists about their experiences with this species, and found that relatively little was known. In 1987, I began a more detailed investigation, and received financial assistance from the Lois Almon Small Grant Program sponsored by the Wisconsin Academy of Sciences, Arts and Letters, The Nature Conservancy, and The Bureau of Endangered Resources in 1989 and 1990. I was also fortunate to have a willing and able assistant in my father, Ray Sullivan. Together we have uncovered many details of the great copper's existence.

We've numbered individual butterflies, to find out how many were in the population, how long they survived, and what their movements were like. We've tracked females to learn more about mating and egg-laying behaviors. We've searched out the tiny caterpillars that start out feeding by day in early spring, then switch to hiding by day and feeding at night as the season progresses. We've observed ants that may deter predators associated with the caterpillars, and have detailed the specialized glands the caterpillars use to attract the ants using scanning electron microscopy. And, we continue to follow various leads to map the distribution of great coppers in the state and to learn more about their habits.

One aspect that has become apparent is that great coppers tend to be found in areas that have had human disturbance. This may prove to be unfortunate for the butterfly, because unlike a prairie remnant or wetland, these disturbed habitats are not likely to be set aside for conservation. We found that many sites where the butterflies had occurred in the past have undergone development, and the once suitable habitat is no longer there.

Last summer we discovered a colony on a site that was being surveyed for construction. Barely two steps ahead of the bulldozers, we dug out the necessary food plants and collected as many of the the tiny eggs as we could find. With assistance from the staff at Wehr Nature Center, we are attempting to relocate the colony within Whitnall Park and should know shortly if our efforts have paid off. What we learn may help to insure that great coppers remain a part of Wisconsin's butterfly fauna, and hopefully we can continue to explore the many unsolved mysteries about the lives and survival of the great copper butterflies that await further investigation.