It’s time once again for one of the world’s most famous light shows — and it doesn’t even use lasers or electric lights.
Synchronous fireflies, or Photinus carolinus, aren’t your run-of-the-mill fireflies. There are more than 2,000 firefly species in the world, but only around a dozen of them can coordinate their flashes. Of that number, only three species of synchronous fireflies are found in North America, according to the National Park Service (NPS).
Here’s why they are called “synchronous.”
Firefly flash patterns are part of their mating display, which helps males and females recognize and find each other. The synchronous male fireflies flash in unison so females can be sure they respond to the males of their species. Then, after a pause, the males flash in unison again. As more males join in, the flashing grows faster and covers a larger area.
“Seeing these fireflies for the first time is magical,” said Orit Peleg, a physicist who studies synchronous fireflies at the University of Colorado Boulder, according to National Geographic.
“The entire forest is flashing together in unison.”
If you want to see the synchronous firefly display, you’ll need to act quickly. Adult fireflies only live 3–4 weeks and their mating season lasts for 2–3 of those weeks each spring.
Here are three spots in the U.S. where you can see the synchronous firefly display.
Great Smoky Mountains National Park
Tennessee, North Carolina
Great Smoky Mountains, the most-visited U.S. National Park, features more than 800 miles of hiking trails, cascading waterfalls, and over 500,000 acres of forest home to a wide variety of wildlife — including approximately 1,500 black bears and more than 1,500 flowering plant species.
While the park is home to at least 19 species of fireflies, it also has a large synchronous firefly population.
NPS scientists will announce synchronous firefly viewing dates for this year on April 25.
Watching the synchronous display has become popular. It has become so popular that the park can no longer accommodate all the people who want to see the display. Instead, Great Smoky Mountains now holds a lottery for parking passes.
“Due to high demand, tickets are awarded using a lottery system to ensure everyone that wants a ticket has an equal chance of getting a ticket,” the NPS explains.
The lottery for vehicle passes will open at 10 a.m. on April 28, and it will close at 8 p.m. on May 1. All lottery applicants will then be notified if their application was successful or not on May 11.
A total of 800 vehicle passes will be distributed for the 8-day event; 100 passes for each day.
All lottery applicants will be charged a $1 application fee. Those who are awarded a parking pass for 1 day of the event will be charged an additional $24, which will be charged to the same credit or debit card used to pay the application fee.
Importantly, lottery winners must occupy the vehicle when it arrives at the park, and they must present photo identification that matches the name on the parking pass. Otherwise, the vehicle will not be admitted to the parking area.
The synchronous firefly viewing area will be at the Elkmont area, near the Little River and Jakes Creek Trailheads.
You can learn more about the lottery, including directions and parking information, lottery details, and details about the viewing area, at Recreation.gov’s Great Smoky Mountains Firefly Viewing Lottery webpage.
Congaree National Park
The 26,276-acre Congaree National Park used to be known as Congaree Swamp, which gives you an idea of what the park is like. While the park is a wetland, it is also the largest remaining intact expanse of old-growth bottomland hardwood forest in the southeast U.S.
Congaree, like Great Smoky Mountains, is also home to a large synchronous firefly population. Since demand to see the firefly display far exceeds the park’s capacity, it too is using a lottery system to ensure a fair distribution of parking permits.
This year, Congaree’s synchronous firefly viewing events will be held May 13–16 and May 19–24, the NPS explains.
The parking permit lottery will open at 10 a.m. on April 6, and it will close at 10 a.m. on April 12. Applicants will be notified whether or not they will receive a parking pass on April 17.
There will be 130 vehicle passes available for each evening of the event.
All lottery applicants will be charged a $1 non-refundable application fee. Lottery winners will also be charged $24 for the parking pass to the same credit or debit card used to pay the application fee.
As you would expect, vehicle pass holders must be in the vehicle when it arrives at the park, and they must present photo identification that matches the name on the vehicle pass.
The firefly viewing area is located near the Harry Hampton Visitor Center.
You can learn more about the lottery, including details about directions, how the lottery works, and the park’s viewing area, at Recreation.gov’s Congaree National Park Firefly Viewing Lottery webpage.
Allegheny National Forest
Located in northwestern Pennsylvania, roughly 125 miles north of Pittsburgh, Allegheny National Forest is comprised of 514,029 acres. Interestingly, September 24, 2023, will be the 100th anniversary of its designation as a national forest.
The Allegheny National Forest is known for Hickory Creek and Allegheny Islands Wilderness Areas, Hearts Content and Tionesta National Scenic Areas, and Tionesta Research Natural Area (the largest contiguous tract of old-growth forest in Pennsylvania).
While the forest is home to more than 15 different species of firefly, it also has a sizable synchronous firefly population.
An Allegheny National Forest spokesperson told TravelAwaits that it is possible to see the synchronous display in the forest. If you want to see the fireflies, rangers can offer some viewing tips, however, there is no designated viewing area and no scheduled viewing activities, according to the spokesperson.
You can learn more about visiting the forest at Allegheny National Forest.
Know Before They Glow
If you will be traveling to see the synchronous firefly display, there are some tips you’ll need to follow.
First of all, keep in mind that since flashlights’ bright white bulbs disturb the fireflies, you’ll need to cover your flashlight with red cellophane or use a red filter. You’ll also need to only use your flashlight when walking to your viewing spot — and even then you’ll want to make sure it’s pointing at the ground.
Finally, be sure to always stay on the trail and stick to the designated viewing area.
While you’re thinking about it, be sure to also read all of our wildlife content, including: