The glow of love came early to the Smokies this year.

The brief, yearly light show of the synchronous fireflies’ mating season happened on nature’s time, not on the calendar of the National Park Service. The insects usually begin their choreographed lighting around the first of June, but this year they started about a month earlier, the Knoxville News Sentinel reported.

And it threw off park officials who had sold tickets and parking passes for the popular display.

Synchronous fireflies might be likened to lightning bugs on steroids. In a two- or three-week mating ritual, the males go to well-timed, flashy extremes to please a female. They all flash on and off, on and off, on and off five times — simultaneously. Then the woods go dark for a few seconds until the boys again crank up their choreographed shimmer.

“It’s all about timing. And it shows the insect brain isn’t as simple as you think it is,” said Jonathan Copeland, a Georgia Southern University professor who formally “discovered” the fireflies and has studied the little-known but very showy species — Photinus carolinus.

Copeland said that, of the 2,000 or so species of fireflies worldwide, only two are scientifically proven to use synchronicity — defined as repetitive, concurrent group flashing. And the other bonafide synchronous firefly is in Southeast Asia.

So the little flashers of the Elkmont area of the Great Smoky Mountains are the stars in North America. The show at Elkmont is now so well known that the Park Service sells trolley tickets to about 8,000 to 12,000 visitors who throng the park for two weeks in early June each year to see them.

Their simultaneous flashing is more than a beautiful quirk of nature; it’s a mechanism of ensuring the survival of the species. The flashing pattern is a way for a female firefly to see through “the visual clutter” of a field of many flashing male fireflies in the night sky and make sure that she’s attracting her own species, Copeland said.

He and another laboratory researcher simulated male flashes with five female synchronous fireflies using LED lights. They varied times and patterns of flashes, but the females only flashed their own response when the LEDs flashed regularly and simultaneously.

A couple of years ago, Hixson resident Landon W. Hartman Jr. and his family discovered that their Elkmont camping trip happened to be at the right place at the right time for that year’s crop of blinking bugs. Hundreds of thousands of the bugs flash like strings of holiday lights in the woods, he said.

“They are a sight to behold. It turns the mountains into Christmas time,” he said. “It’s unbelievable. It’s hard to imagine unless you have seen it. And it’s hard to describe. They are nothing like the fireflies we have here. I was absolutely in awe the first time I saw them.”

Copeland and Becky Nichols, a National Park Service entomologist, said synchronous fireflies aren’t just in the Smokies but also are scattered in pockets throughout the Southern Appalachian Mountains.

“I would be surprised if you didn’t have some” on portions of the Cumberland Plateau, Copeland said. But in those smaller populations, the synchronicity is much less obvious and easy to mistake for randomness.

Elkmont’s population, on the other hand, is so dense that the synchronous flashing is clear and hard to miss.

“When there’s a huge concentration, it is a spectacular sight. It’s more like a wave of light. Then they all stop. Then there’s another wave,” said Todd Witcher, who for the past two years had used the firefly show as a fundraiser for his nonprofit group Discover Life in America. Based in the Great Smoky Mountains National Park, the group is inventorying all the species of plants and animals in the park.

On Bug Time

But this year, Mother Nature and the short-lived synchronous fireflies made their own schedule.

A mild winter and an early spring brought the bugs — including the fireflies — out about a month sooner than usual, said Nichols.

Peak firefly season was supposed to begin Saturday and end near June 10. That’s when the Park Service scheduled trolleys to carry the 1,100 to 1,500 people a night to see the show. The park sells $1.50 parking passes and $1 round-trip tickets on the trolley, but officials say the park doesn’t receive any money from the passes or the trolley tickets.

Last week, the Park Service broke the bad news on its Great Smoky Mountains Synchronous Fireflies web page.

“Park biologists predict that while there may still be some activity during the weekend of June 2, the display will be past peak and may taper off to nothing well before the following weekend,” according to a statement from the park public affairs office.

Parking passes and tickets for the trolleys — arranged to keep gawkers from parking on the very ground where the fireflies live — went on sale April 30 and were sold out within days.

“We regret any inconvenience or disappointment this may cause you,” states the Park Service.

Nichols said that by the time park officials realized the bugs had revised their schedule, it was too late to make massive staffing and trolley contract changes.

“Next year, we’re going to look a little harder at temperature dates, and we’re also going to require our contracting be a little more flexible,” she said.

For now, the light show is winding down, and the fireflies are dying off — a normal occurrence each year, Nichols said.

About three weeks after the very-demanding females choose their mates and lay several clutches of eggs apiece, the eggs hatch into larvae, and the larvae burrow into the ground for one or two years. Underground, they spend their days and nights eating larvae of snails and slugs.

“Everything has a function at some point in the whole diversity of things,” Nichols said. “Fireflies are a well-functioning part of the forest floor, and they spend most of their lives as a little predator in the ground.”

Come another spring, they will emerge for another glowing spring fling.