The staff at the Peggy Notebaert Nature Museum in Chicago, for instance, recently released nearly 200 Baltimore Checkerspots they'd raised from egg to winged adult. It was their first successful crop, said curator Doug Taron, made possible by the accidental discovery that the caterpillars need to over-winter in a wetter environment than other butterfly species.
"It's really not difficult to breed them," said Durkin. "What is difficult is to maintain the breeding population for any number of years."
With little success so far in captive breeding, experts say their focus is on trying to protect the remaining butterfly populations that they know of.
"Our first line of conservation is to preserve what habitat we have," said Durkin. She lives in Maine but returns to Maryland in late spring every year to check up on the Baltimore Checkerspots and teach a class on butterflies. She said she's been spending time this year consulting with residents on a privately owned butterfly haven near Kitzmiller in Garrett County, counseling them on how to maintain the habitat.
Prior captive-rearing failures haven't daunted butterfly lovers like Kreiley, though. She and her volunteers were coached by Denise Gibbs, a naturalist at Montgomery's Black Hill park.
They collected one plant with caterpillars on it from the last known Baltimore Checkerspot habitat in the county, a small open wetland in Clarksburg — the state's most rapidly growing community, according to the latest census. The land all around this spot is bulldozed, though Gibb said the developer has pledged to work with county officials to protect and even enhance the wetland.
The volunteers collected and raised their own white turtlehead plants, and planted some in four spots on other county parkland that had been scouted for apparent suitability. Gibbs said that when the captive butterflies emerged in the spring and were being taken to be released, they started mating in the small cage in which they were being transported. Some female butterflies started laying eggs as soon as they were placed on the turtlehead plants.
"So far so good," said Gibbs. But, she adds, "Nobody seems to know what this butterfly needs. We're learning things as we go."
Ruth Eisenhour at the Harford Glen Environmental Education Center in Bel Air also thinks her captive-rearing efforts, carried out with the assistance of Harford County school students and Scouts, are gaining traction.
She said they've managed to take about 30 caterpillars given to them by another breeder in Carroll County a few years ago and build that to about 3,000 last year. This year, Eisenhour said, for some reason the number of caterpillars inside the school's enclosures declined. But she noticed more outside the fenced-in plants, meaning they likely came from butterflies released in prior years.
"I knew nothing about butterflies before I started this," said Eisenhour. "I don't know why this in particular appeals to me. … I'm an animal lover, and you hate to see things just decline and disappear." But in spring, in the few weeks when the butterflies are flying around on school property, Eisenhour said, "it's pretty cool knowing that our kids are the reason they're there."