LILBURN - On warm summer evenings, Gwen and Paul McDonald's yard looks like Christmas, alight with the glow of thousands upon thousands of fireflies.
Gwen, a retired Trickum Middle School teacher, became fascinated with the so-called "charismatic coleoptera," or fireflies, upon seeing the first mass population swarm her yard five years ago. She has since made the appearance of the fireflies a social gathering, turning warm summer evenings at her home into a new kind of garden party.
As of late, the McDonalds' home has become a bit of a neighborhood gathering spot thanks to these gleaming and acrobatic characters. Gwen prints her own "Annual Firefly Fling" packet the first weekend of June, chock full of firefly facts, and neighbors and family, including the McDonalds' young grandchildren, gather to watch the display.
"I never knew what to do with them," said Gwen. "So we would set up chairs and watch them like Christmas lights in the trees."
Fireflies, or "lampyridae," are winged beetles which appear inconspicuous in the daylight but transform into mobile incandescent lamps beginning at twilight. These fireflies partake in a luminescent mating dance, using patterns and a flash of color to attract others of the same species.
This light show by the males creates a luminous dance of distinctive blink patterns for an audience of eager females to interpret and distinguish. The response is a corresponding blink to alert the male and arrange for a meeting.
James Lloyd, a professor at the University of Florida and an expert on fireflies, compared the mating ritual to that of a college bar. The flash patterns fireflies demonstrate, he said, are the tactics used to entice a mate, much like with changes to human appearance such as dress, hair style or make-up.
"This is kind of what human life is like," said Lloyd, who teaches a course in biology and natural history with fireflies. "I tell most of my classes that it's like what they see in a bar."
Kathrin Stanger-Hall and David Hall of the University of Georgia visited the McDonalds' home in mid-June to witness the display. The researchers reported the presence of fireflies of the Photuris genus, the so-called "femme fatales" of North American fireflies. These fireflies prey upon flying males by mimicking particular signals and luring them to hover near the ground, only to consume them. These unscrupulous tactics work to protect the Photuris from potential enemies.
Most genus of fireflies possess a particular chemical which is an unpleasant taste for its predators. Photuris lack this particular chemical, but the consumption of other fireflies provides the Photuris with the necessary protection.
Regardless of the predation occurring in her yard, Gwen is thrilled by the presence of the fireflies.
"The karma is great," she said, suggesting her belief that the happening she witnesses annually must be an indication of good luck.
Stanger-Hall attributes the large populations at the McDonalds' home to the conditions of their yard. Paul, a retired banking and mortgage president, is prohibited under doctor's orders from working in the yard, so the conditions have fallen to an unkempt state. Paul jokingly references similarities to the dense forest growth of "Jumanji," the 1995 Robin Williams fantasy film.
The ground cover of the yard, along with excess moisture, a lack of pesticides and minimal yard service, creates a suitable environment for the fireflies to flourish as part of their nearly two-year developmental cycle.
"(The McDonalds) have huge old trees with undergrowth," said Stanger-Hall. "It's the perfect firefly habitat. They have those long, undisturbed patches of grass and growth, and they have ivy that keeps the soil below it moist."
The Halls noted that the gathering in Lilburn was the largest they had seen since they had left Texas, where Hall, a professor of genetics, and Stanger-Hall, a professor of biological sciences, formerly worked at the University of Texas at Austin.
Recent reports have mused on the dwindling populations of fireflies, and experts fear the days of illuminated Mason jars may soon come to an end. Don Salvatore, a science educator at the Museum of Science in Boston, believes the problem is the decrease in suitable habitats such as the McDonalds' yard.
"Fireflies seem to be disappearing, but without empirical evidence, it's hard to say conclusively," Salvatore said. He cites urban sprawl, pollution, use of pesticides and environmental conditions for the fluctuation in appropriate locales.
Salvatore is on a team at the Museum of Science which developed Firefly Watch, a program that encourages public monitoring of firefly populations.
One of the primary goals of the program is education of the public, Salvatore said.
"We want to get people to appreciate fireflies," he said. "They're such captivating creatures. People see them, and they're just intrigued by them."
The McDonalds are no exception. Gwen has heard the speculation of the disappearance of fireflies, and she says that the Halls informed her the large-scale occurrence should last no longer than five years in succession. Regardless, she remains optimistic about her beloved yuletide summer.
"Because it's the fifth year, and we still saw so many," said Gwen, "I have to believe that they'll be back."