East Lyme — While various forms of gender identity may be a hot topic in the human world these days, a black swallowtail butterfly that’s become something of a local celebrity in its short life adds a new layer of intrigue to notions of male and female.

Maryann Nazarchyk, a landscaper and member of the Connecticut Butterfly Association, noticed something unusual about one of the black swallowtails she raised at her home in Niantic. Nazarchyk has been collecting butterfly eggs on host plants in her backyard since the 1990s, letting them hatch and grow indoors before releasing them in an effort to help boost native butterfly populations.

“This is the rare one,” she said Monday, gesturing toward a mesh laundry hamper in her living room with a large black butterfly fluttering inside. “It’s half male and half female. The blue side is female and the male side is yellow.”

Normally, the female of the species is black with large blue spots, and the male is black with large yellow spots. This one, known as a gynandromorph, possesses the appearance and the sexual characteristics of both the male and female, a "1-in-tens of thousands" developmental anomaly, said Professor David Wagner, entomologist at the University of Connecticut.

"Something happens at the two-cell stage," Wagner said. The female chromosomes click on for one side, but the male chromosomes govern the other. The creature is "absolutely sterile," but "really cool," he said.

"It's pretty spectacular," said Wagner. "I've never seen one in my 50 years of entomology." Butterfly collectors, he said, would pay "many thousands of dollars" for an gynandromorph.

The events that produced the rare creature began a few weeks ago, when Nazarchyk collected some tiny yellow swallowtail eggs from a fennel plant in her garden. After they hatched into caterpillars, she cared for them as they grew and each formed a chrysalis, which is like a cocoon. After a week or so, the rare butterfly began to emerge from one. She didn’t notice anything unusual at first, but after a couple of days, when she brought it outside to release it on a parsley plant, she saw the unique patterns on the wings.

“So many of them I release get eaten right away by the birds, I thought this one was a little too special to see that happen,” she said.

So she brought it back inside and fashioned a home for it out of the mesh laundry hamper, at first feeding it orange Gatorade.

“I’m going to put some zinnia I just cut from my garden in there for it to feed on,” she said.

On Saturday morning, she took the butterfly to a butterfly walk sponsored by the Salem Land Trust. The 40 or so people who met her in the parking lot of the Walden Preserve greeted her and her winged passenger enthusiastically. She opened the laundry hamper insider her car, then gave everyone who wanted to a chance to get inside to get a photo of the butterfly in flight.

“It was like we were celebrities when I drove in,” she said. “It was so much fun. None of us are probably ever going to see one of these again.”

She plans to keep the butterfly for at least a few more days before bringing it to an entomologist at the Peabody Museum in New Haven. Before it’s dissected for research or put on display, she said, she wants to enjoy watching her once-in-a-lifetime guest a little longer.

“I’ve promised it to the Peabody,” she said. “I understand the scientific value of it.”

Wagner said the swallowtail will probably only live a few more days. But in its short life, it's providing an important reminder that nature often defies human efforts to be ordered into distinct categories. 

"Life is complicated," he said.

j.benson@theday.com