Up and down the Eastern US, fireflies (or lightning bugs) are an essential part of summer nights, twinkling against the dark sky as they search for a mate. But in certain pockets of the Southeast, the unique synchronous firefly (Photinus carolinus) puts on an extraordinary summer display. In large enough populations, these fireflies will all flash the lanterns on their abdomens at the same time, then go completely dark for six seconds—lighting up the forest and creating a spectacular visual experience that can’t be captured on camera.
Though there are many species of fireflies in North America, synchronous fireflies are unique because of their distinct flash pattern, alternating bright light with moments of total darkness for hours on end. This is all part of their mating ritual—after roughly a year of crawling around the forest floor as larvae, adult fireflies only have 21 days to find a mate. Male fireflies zoom around hardwood forests, flashing in perfect harmony, and female fireflies respond from the ground with two quick blinks to mark their location.
These fireflies have different mating seasons throughout the summer depending on their exact location, but they’re generally active from late May through early June. The largest and most well-known firefly event occurs in Great Smoky Mountains National Park around the first week of June. The best time of day to view the fireflies is right after dark, usually from about 9pm to midnight.
As synchronous firefly viewing events have grown in popularity, it’s increasingly important to follow guidelines to help protect this insect. Try a red-light headlamp, or, if you bring a flashlight, cover it with red or blue cellophane, as regular light can confuse the fireflies’ natural rhythm. Point your flashlight at the ground, and turn it off when you arrive at your viewing spot. Do not catch fireflies, and be sure to stay on the trails so as not to disturb their habitat. Always remember to recreate responsibly and leave it better when spending time outdoors.
The largest population in the Western Hemisphere is situated near the northern edge of Great Smoky Mountains National Park in Tennessee and parts of the park in North Carolina. The region has drawn international attention over the last few years from visitors hoping to see one of nature’s best light shows. Read on to discover where to see them this year!
Elkmont Campground is the most well-known location for viewing synchronous fireflies, and for good reason. Every year, the Elkmont area attracts thousands of fireflies that put on a dramatic light show. Be warned, this show is an exclusive one—the National Park Service only issues coveted Elkmont parking passes on a lottery basis. This year, only 800 lucky lottery winners will score front-row seats. The lottery opens on recreation.gov on Friday, April 30, at 10am and ends Monday, May 3, at 11:59pm.
If you didn’t win a ticket, you can consider visiting Elkmont in the days before or after the regulated viewing. While there is no guarantee that you will see fireflies outside of their peak mating dates, there is a chance you’ll spot some early bloomers or fashionably late bugs.
Roughly an hour west of Elkmont inside Great Smoky Mountains National Park, Cades Cove is also known to host fireflies for their mating season. Head to the Abrams Falls trailhead for your best chance of seeing a show. Just be warned, the main gate to Cades Cove Road closes at sunset—the park rangers might not kick you out immediately, but don’t get too comfortable as you watch. On Wednesdays, this road is closed to vehicles and only open to bike and pedestrian traffic.
Just outside of Gatlinburg, the Rainbow Falls trailhead is one of the most convenient viewing areas for synchronous fireflies. Arrive early to snag a parking spot at either of the two small parking areas along Cherokee Orchard Road. If lots are full, keep driving to reach a handful of other parking areas, overlooks, and pull-outs just a few miles down the road.
Score a ticket to Rocky Fork State Park’s firefly light show, and you’ll get the chance to see both synchronous fireflies and blue ghost fireflies in one incredible event. Like other parks on this list, Rocky Fork State Park has implemented a lottery system, only allowing eight vehicles per night to view the show. Find out more about the chance to win on their website.
Synchronous fireflies have also been spotted throughout the Cataloochee Valley, but their exact location is harder to get to. Let’s just say you should expect to do some hiking, preferably as part of a guided tour (for your own safety and the sake of the fireflies). If you don’t see synchronous fireflies in Cataloochee Valley, you still might catch sight of otherworldly blue ghost fireflies, whose continuous blue-white lights create a maze of beams across the forest floor as they zoom around in search of a mate.
Joyce Kilmer is famously one of the most impressive old-growth forests in the country, but its high density of hardwood trees also makes it an ideal habitat for synchronous and blue ghost fireflies. The only way to see the forest is on foot—walk along the 2-mile trail looping through 400-year-old trees and find a bench to post up and watch fireflies light up the night.
South Carolina’s Congaree National Park held its first Firefly Festival in 2017. By 2019, the event had grown into an 18-day celebration attracting more than 12,000 visitors from around the world. To limit numbers and protect fragile firefly habitat, the park is now limiting festival attendance to just four days (May 20-22 and May 27-29 in 2021), and introducing a lottery system for vehicle passes. If you don’t score a ticket to the official fireflies event, try visiting the park in the days right before or after. Just be sure to check guidelines at the official park website, as there are increased visitor regulations throughout May.
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