GREAT SMOKY MOUNTAINS NATIONAL PARK — The synchronous firefly oracle has spoken.

Dr. Becky Nichols, the park entomologist, has been hard at work since March 1 taking ground and air temperature readings, plugging data into formulas and looking at long-range weather forecasts to come up with the precise date the world-famous synchronous fireflies will do their ritual mating flash dance in the Great Smokies.

The result?

“I’m predicting it will be May 30-June 6 this year,” Nichols said on April 23.

Every year in late May or early June, thousands of visitors gather near the popular Elkmont Campground just over the border on the Tennessee side of the Smokies to observe the naturally occurring phenomenon of Photinus carolinus, a firefly species that flashes synchronously, lighting up the pitch-black forest to “oohs” and “aahhs” from the thousands gathered.

Since 2006, access to the Elkmont area has been limited to shuttle service beginning at Sugarlands Visitor Center during the eight days of predicted peak activity to reduce traffic congestion and provide a safe viewing experience for visitors, while also minimizing disturbance to these unique fireflies during the critical two-week mating period.

The flashing phenomenon has become so well known around that world that the park has instituted a lottery system for all visitors who want to view the synchronous fireflies at Elkmont. They must have a parking pass distributed through the lottery system at www.recreation.gov.

The lottery will be open for applications from 8 a.m. April 26 to 8 p.m. April 29, said park spokeswoman Dana Soehn. Results of the lottery will be available May 10.

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A total of 1,800 vehicle passes will be available for the event which includes: 1,768 regular-parking passes (221 per day), which admit one passenger vehicle up to 19 feet in length with a maximum of seven occupants, and 32 large-vehicle parking passes (four per day) which admit one large vehicle (RV, mini-bus, etc.) from 19-30 feet in length, with a maximum of 24 occupants.

Lottery applicants must apply for either a regular-parking pass or large-vehicle parking pass and then may choose two possible dates to attend the event over the eight-day viewing period, Soehn said.

It costs $1 to enter the lottery system, which uses a randomized computer drawing to select applications. Those who win a coveted parking pass will have to pay a $24 reservation fee. This is up from the $20 fee last year.

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The parking pass allows visitors to park at Sugarlands Visitor Center and take the trolley shuttle service to Elkmont, which costs $2 per person. The fee covers the cost of awarding the passes, event supplies, one red-light flashlight per pass, and nightly personnel for managing the viewing opportunity at Sugarlands Visitor Center and Elkmont.

Parking passes are nonrefundable, nontransferable, and good only for the date issued. There is a limit of one lottery application per household per season. All lottery applicants will be notified by e-mail by May 10 that they were “successful” and awarded a parking pass or “unsuccessful” and not able to secure a parking pass.

Is the lottery hassle all worth it?

The park started the lottery system in 2017.

Last year, 22,000 people applied, and only 1,800 parking passes were awarded, with a maximum of six people per car.

So, the answer seems to be “yes.”

Those lucky enough to snag a campsite at Elkmont were able to walk into the viewing area, a dirt path lined on one side by the scenic Little River, and the other by a dense montane alluvial forest of deep leaf litter and closed in canopy of mature oaks, hickories, hemlock and tulip poplar – the type of habitat synchronous fireflies love.

Last year visitors ranged in age from infants to teens to parents and grandparents, who came from 41 states, including Alaska and California, plus Puerto Rico, Canada and the Philippines.

Some visitors last year came especially to see the fireflies, or incorporated their family summer vacations around the event. It’s not hard to do, since the Smokies, the most visited park in the National Park Service, covers a half-million acres of rugged, scenic forest across Western North Carolina and Eastern Tennessee, with 900 miles of hiking trails, countless streams and waterfalls and historic buildings to explore.

But the synchronous fireflies are so rare, they have become a bucket list for nature lovers, much like the lights of the aurora borealis.

All visitors are asked to turn off phones and flashlights to allow perfect, movie-theater-dark viewing for everyone. Naturally, it seems, people speak in hushed tones, as if in church, watch the forest from their lawn chairs.

The lucky ones thought ahead and reserved a spot at the 220-campsite Elkmont Campground, where you can walk to the Little River Trail to see the firefly show. However, campsites can be reserved six months in advance on Recreation.gov, and the site is showing that the campground is completely booked for late May and early June.

The rest can camp at other parts of the park or stay overnight in nearby Gatlinburg, Tennessee.

What makes these bugs so special?

Synchronous fireflies are one of at least 19 species of fireflies that live in the Smokies, Nichols said. They are one of only a few species in the world known to synchronize their flash patterns.

This insects' reproductive display occurs for a couple of weeks every year throughout its range (southern Appalachians), and is typically in late May or early June in the Elkmont area of the park.

Only the male fireflies flash as they fly between 2-6 feet above the forest floor, as they try to signal to the female that they are the right species for mating, Nichols said. The female firefly does flash, but it’s very faint so most people can’t see her from where she’s crawling on the ground. The females don’t fly.

Nichols said all of her fastidious calculations point to the fireflies putting on their show roughly the same time period as last year, when it was the second week in June.

Watching the weather for fireflies

The biggest factors are the temperatures in March and April – will it be warm enough for the firefly larvae to grow and emerge from the ground.

“It’s a little stressful watching the weather to match what the temperatures are going to be,” Nichols said.

“Last year it was difficult to predict because we had a really cold March, but it was predicted to be a really warm May, so we pushed it ahead,” she said. “The projected temperature – the projected highs and lows for the rest of April and May – are predicted to be somewhat normal.”

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According to Steve Wilkinson, meteorologist with National Weather Service in Greer, South Carolina, March and April 2018 were below normal in the Elkmont area. The average temperature in March 2018 was 44.9, while the average overall temperature is 47.4 degrees.

April was also cool. The average for 2018 was 51.8 degrees, while the normal is 55.5.

This March is closer to normal, Wilkinson said, where the average temperature was 45.1 degrees. April’s average temperature through April 22 has been 56.4, while the normal through this date is 54.4 degrees.

The precipitation, while in Asheville has been off the charts, has been tracking close to normal in Elkmont. Nichols said precipitation doesn’t have much of a bearing on when the fireflies will start to flash.

What happens if you don’t get the winning ticket this year? Be creative, Nichols said.

“They do occur in other places, but I haven’t seen another place with as large a population as Elkmont. They range as far north as the Allegheny Mountains. I encourage people to find other places. It has to be the right time of night, about 9:30-10 p.m., and in right habitat,” she said.

“They like a rich forest floor, with lots of leaf litter and detritus, moist conditions, an open understory with a closed canopy, so when they’re flashing, they’re more able to see each other.”

Want to see the synchronous fireflies?

The Great Smoky Mountains National Park will open the Elkmont area to synchronous firefly viewing May 30-June 6. The lottery for a vehicle pass to park at Sugarlands Visitor Center and get a trolley to the viewing area will open April 26-29.

To enter the lottery, visit www.recreation.gov and search for “Firefly Event,” or call 877-444-6777. For more information about the synchronous fireflies, visit the park website.