News

Rare Butterflies Settle In
at Gensburg-Markham

With help from a picnic cooler and some potted plants, the Chicago area’s rarest and possibly most spectacular butterfly — the regal fritillary — is finally settling in at one of its former stomping grounds.

The reintroduced regal fritillaries appear to be doing well at Gensburg-Markham Prairie, in the south Chicago suburbs. At least that’s what Chicago Wilderness photographer Thomas Bentley found when he photographed them over the summer. (See his photos here.)

Right now, though, in the dead of winter, the tiny regal caterpillars are lying dormant on the prairie ground, waiting for spring.

That the regals are getting established in their new home is highly encouraging to researchers Doug Taron, of the Peggy Notebaert Nature Museum, and Ron Panzer, of Northeastern Illinois University. The flashy insect disappeared from Gensburg-Markham Prairie in the late 1970s, an unintended victim of human encroachment. In late 2007, however, the biologists drove to a small prairie at Beaver Lake Nature Preserve, just over the border in Indiana, where the nearest population survives. With the blessing of the site’s owner, The Nature Conservancy, they collected a handful of pregnant females and tucked them into a chilled picnic cooler for the ride back to the office. Once in the museum lab, the butterflies were shown to potted wooly blue violets (violets are the sole food of the regal fritillary caterpillar) and both were covered with a swath of cotton muslin fabric. Sure enough, the butterflies laid eggs, which hatched into caterpillars. Once they had formed cocoons, the butterflies rode in their picnic cooler to the high-quality Gensburg-Markham Prairie. There, the cocoons were affixed to wild plants.

While most butterflies lay eggs directly on their host plant, regals lay their eggs throughout the prairie in late fall. The newborn caterpillars overwinter, waiting to eat until spring, when the leaves of violets emerge.

— Kelly McIntyre