Special type of firefly discovered on Grandfather Mountain

Special type of firefly discovered on Grandfather Mountain

Synchronous fireflies light up an overlook just below Grandfather Mountain’s Mile High Swinging Bridge. (Jim Magruder)

LINVILLE, N.C. — The discovery of synchronous fireflies on Grandfather Mountain has experts aglow with excitement.

The park in Linville, North Carolina, is officially home to Photinus carolinus, the only species of firefly in North America that can synchronize their lighting display, meaning they can flash in unison.

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Synchronous fireflies have become a major draw for visitors to the Great Smoky Mountains National Park. Hopeful spectators enter a lottery to win tickets to witness the phenomenon that generally occurs from late May to early June. With a limited number of tickets available, the event has grown ever more exclusive.

Now, it’s grown a mile high!

Dr. Clyde Sorenson, an entomologist from North Carolina State University, discovered the firefly on Grandfather Mountain while staying overnight in the park’s guest cottage.

“I had the intention to see what kind of fireflies might be around at the high altitude,” Sorenson said.

When he saw a few fireflies flashing, he knew right away that it was something special.

“As it got dark, the numbers steadily went up, and between 10 and 10:30 p.m., there were several hundred all around the guest cottage and Woods Walk, flashing synchronously,” Sorenson said.

He later confirmed his findings with East Tennessee naturalist Lynn Faust, a preeminent expert on the subject who also wrote a field guide on fireflies.

Sorenson is particularly excited, because synchronous behavior is rare in fireflies.

“There’s only a handful of species all around the world that do this, and for a long time, this particular species, the phenomenon of seeing large numbers of them synchronizing has been associated tightly with just a couple geographical areas,” he said.

What makes Grandfather Mountain such a unique location, Sorenson said, is its elevation range. Starting at a relatively low elevation of 3,000 feet, the mountain reaches up to nearly 6,000 feet.

According to Sorenson, the fireflies are really active for about two to three weeks, and then they’re usually done for the year. But because of Grandfather Mountain’s elevation span, it’s possible that the display could last for several weeks.

This would be a boon for the scientific community and spectators alike.

“Any time people can witness one of these really neat natural history spectacles, it increases their appreciation for the natural world and their interest in helping preserving it,” Sorenson said.

“It tickled me to no end. I was kind of giddy for a little bit,” he said.

With the fireflies now out of season, park staff is in the process of organizing future viewing events during which the public can witness the bugs in action.