As biologist Doug Taron watches with the anxious pride of a new father, dozens of tiny and nearly invisible caterpillars have been hatching in a bank of screen-sided cages in his lab at the Peggy Notebaert Nature Museum.
If all goes well, they will grow into swamp metalmark butterflies, an extremely rare species with striking silver markings on russet brown wings, and Taron will succeed in establishing a new colony at an Elgin nature preserve, replacing a population exterminated by human incursion decades ago.
Taron is hoping for the first successful wild butterfly reintroduction–a process known scientifically as “translocation”–in Illinois. Tried on a grand scale with species such as the California condor, translocation is being attempted with an increasing number of threatened species, though it is often tricky and results are spotty.
Saving a rare and delicate little creature that most people might never notice may seem like a nice but largely meaningless gesture. But wild butterfly populations, battered by climate changes and caught in a deadly crossfire of insecticides, offer clues to scientists looking for symptoms of distressed and deteriorating environments.
“Butterflies have become an important monitor to the health of the environment, because they are easily noticeable,” said Thomas C. Emmel, a University of Florida zoology professor. “They can show how things can go to hell in a handbasket in a hurry.”
And the destruction of wild butterfly populations in the last decade has been escalating, he said.
To cite just one factor: “Prolonged droughts in the U.S. and the heating up of the climate in general all over the world has advanced the blooming of spring flowers, putting plants out of sync with the butterflies’ cycles,” he said. “That means butterflies are not emerging when fruit plants and nectars they feed on are available.”
The concern over butterflies helped Taron and the Notebaert Nature Museum, located in Lincoln Park, win a $100,000 grant last year from BP, the energy corporation, to fund a project that will reintroduce two butterfly species in Illinois this year.
In addition to the swamp metalmarks at Bluff Spring Fen Nature Preserve in Elgin, Taron is going to reintroduce silver-bordered fritillary butterflies to the 1,100-acre prairie on the grounds of Fermi National Accelerator Laboratory in Batavia this month.
“We would like to do other species in the future,” said Taron, “especially the regal fritillary, which is almost gone from Illinois, and other species that are in trouble, like skippers and the karner blue, that are doing very, very poorly. We need to find out why they are doing poorly and bring them back.”
Other butterfly experts around the country will be closely watching Taron’s work. The biology curator at the Notebaert Nature Museum, he is a biochemist who spent a dozen years as a cancer researcher before joining the museum five years ago. He is an expert in isolating and analyzing DNA material in tissues from living organisms.
From bits of butterfly wingtips about twice the size of the head of a pin, he will determine the genetic diversity of his transplanted colonies. Taron’s genetic work should provide conservationists with better information about how many butterflies they can safely remove to start other populations.
“When you are working with rare and endangered species, you can’t capture hundreds of individuals from the wild,” said Susan Borkin, entomologist at the Milwaukee Public Museum.
Other project successful
Five years ago Borkin succeeded in transplanting a laboratory-raised colony of swamp metalmark caterpillars to a wetland in eastern Wisconsin; they grew into a healthy, self-sustaining wild population. She also helped Taron locate and capture the seven fertilized swamp metalmark females he brought to Chicago to raise caterpillars for Elgin.
“Not all butterfly translocations succeed,” Borkin said. “We think some of them fail because there was not enough diversity in the genetic pool of the restored population, and that they died out due to inbreeding. That’s why working with Doug is great, because he is doing this genetic component that we never had available to us before.”
Taron, in turn, is using Borkin’s colonization techniques to repopulate the Elgin site with swamp metalmarks, which disappeared from there sometime between 1940 and 1980. The last sightings of the species in Illinois were in the 1980s in Downstate Cole and Vermilion Counties.
“We don’t know what caused it to disappear, but we know that species doesn’t do well when its fen habitat is choked with woody vegetation, and between 1940 and 1980 huge amounts of brush and trees moved in,” Taron said.
Swamp metalmarks have always been relatively rare, because they live in a relatively rare natural environment: alkaline wetlands called fens, found in low-lying depressions in prairies. Their life cycles depend on the health of the fens.
The butterflies survive only a few days after emerging from their chrysalis pods in early summer. Almost immediately after emerging, they mate, and in her last few days on Earth, the female lays 50 to 75 eggs on the leaves of swamp thistle.
The eggs hatch in mid-August, and the only plant the emerging caterpillars can eat is the swamp thistle. Late in September, just before the first frost, the caterpillars crawl into rosettes formed by the flowers of the thistle that drop to the ground. Secreting antifreeze into their bloodstream, the caterpillars go into hibernation for the winter inside the protective rosettes.
In the spring, they emerge furry and white, feed for six weeks on the thistle leaves, then pupate, forming their chrysalises, and emerge as butterflies in late July to restart the reproductive cycle.
Taron said he will release his laboratory-raised swamp metalmark caterpillars in the Elgin fen late this month, just before the first freeze.
Casting a wide net
Last week Taron grabbed his butterfly net and chased silver-bordered fritillaries, tawny orange butterflies with 2-inch wingspans, through the tall grass at Grundy County’s Commonwealth Edison Prairie. He captured two dozen gravid females–laden with fertilized eggs–and took them to his lab cages to get them to lay their eggs on potted violets.
In the lab, the hatching caterpillars will pupate by mid-September. Taron will install their chrysalises among the wild violets at Fermilab. He expects them to emerge as butterflies next spring, the first silver-bordered fritillaries to populate that land in about 150 years.
Though they are hard to find, the silver-bordered fritillaries are not endangered. With them Taron will be looking for clues to a mystery.
The prairie at Fermilab is itself an attempt to restore an entire ecosystem, destroyed when it was plowed and planted in the 19th Century. Since reconstruction efforts began in 1975, many characteristic prairie animals–rodents, reptiles and insects–have returned on their own, but many, like the butterfly, have not.
“We know prairie-loving butterflies aren’t always coming back to reconstructed prairies on their own,” Taron said. “It may simply be that there are no nearby populations that could migrate by themselves, so we have to learn how to put them there.”
What Taron is doing on a local scale, Emmel is about to do on a global scale in $8.4 million research laboratories dedicated to studying butterflies and moths he is building at the University of Florida in Gainesville.
Bigger studies planned
Next year the university will open the McGuire Center for Lepidoptera. Built with a donation from William M. McGuire, chairman of the United Health Group HMO, and his wife, Nadine, it will house 6 million specimens, one of the largest collections in the U.S.
The center will concentrate on issues such as climate change and habitat loss, fates often foretold by disappearance of butterflies and moths.
“I don’t mean to sound like a crapehanger, because I am an optimist by nature,” said Emmel in a recent phone interview, “but sometimes I don’t have much hope left for the natural world, and for the kind of natural abundance we now enjoy, because of the rising crescendo of manmade alterations to the environment.
“Maybe the butterflies will play a signal role as a flagship species, getting our attention to these potentially catastrophic changes and setting us on a course of change.”
