GRANDFATHER MOUNTAIN, N.C. (WGHP) — A rare and beautiful sight is underway on Grandfather Mountain and the Great Smoky Mountains as synchronous fireflies light up the sky en masse as they search for a mate.

While you may have known that fireflies glow to attract mates, you may not have known that different species flash in different ways. There are at least 19 different species of firefly in the Great Smoky Mountains National Park, but the synchronous firefly, scientific name Photinus carolinus, is unique.

According to the National Park Service, the synchronous firefly is one of a few species in North America that synchronizes their flashing patterns. The males do this so that the females can differentiate them from other kinds of firefly, some of which are predatory and could pose a threat. At first, a few fireflies may appear to be flashing randomly. But soon, more join in and begin to follow a distinctive pattern: Five to eight flashes. A pause of about eight seconds. Repeat.

“As more males start joining in, the flashing will also begin to synchronize and entire sections of the forest will be pulsating with light,” NPS says.

The synchronous firefly only does this unique ritual for about two to three weeks each year, and the exact time is dependent on temperature and soil moisture. NPS analyzes temperatures to determine when the peak will be, and they say the peak for the Great Smoky Mountains in 2022 is expected to occur between June 3 and 10.

The Elkmont Campground in the Great Smoky Mountains National Park in Tennessee specifically has become a popular destination during this peak season, so NPS has been limiting attendance during these peak days to help control traffic and make sure the experience is pleasant for both guests and the fireflies. All 800 night passes have already sold out for the 2022 peak days of June 3 through 10.

Guests of Elkmont Campground had nothing but good things to say after the 2021 event, calling it an “unforgettable experience” and “absolutely magical.”

But Elkmont and the Great Smoky Mountains aren’t the only places to see the synchronous fireflies—Grandfather Mountain is another great location.

In 2019, N.C. State University entomologist Clyde Sorenson discovered a population of synchronous fireflies on Grandfather Mountain.

“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,” Sorenson said, according to the Grandfather Mountain Stewardship Foundation. “But the species goes all the way from New York to Georgia. Where they have been most widely known and recognized for so long is at Elkmont in the Great Smoky Mountains National Park. But that’s at 2,200 feet. Where I saw them (at Grandfather) was at 4,200 feet.”

Because of Grandfather Mountain’s range in elevation from about 3,000 feet to close to 6,000 feet, the mountain offers more opportunities to see the lights.

“They could start down at the bottom (of the mountain) very early in June and continue well into July, as you go up the mountain, which presents a really unique opportunity for, perhaps, a lot more people to see them over a much longer span of time,” Sorenson said. “Generally, at any given location, they’re really active for about two to three weeks, and then they’re done for the year. But again, because Grandfather has that great elevational span, it’s possible that the display could last for many weeks.”

Grandfather Mountains is holding events focused on the light show for the first time in 2022. However, like Elmont’s, are already sold out. The mountain will be hosting its Grandfather Glows events on June 26 and 29 and July 1, each with an attendance cap of 200 people, and an adult field course on fireflies of North Carolina on June 11.