A peculiar lightning bug in Great Smoky Mountains National Park became a lifelong obsession for one researcher and continues to captivate those interested in science and natural beauty.
Words by JESSICA BRADLEY | Photos by STEPHEN COOK
May 17, 2023
The Smoky Mountains light show started — as most lightning bug displays do — in a backyard on a summer evening. As a child, Lynn Faust watched the insects blink in unison at her family’s cabin in Elkmont, part of Great Smoky Mountains National Park in Tennessee. She sat on the porch every year wrapped in a blanket, marveling at their signature flash pattern: six rapid bursts of light followed by six seconds of dark.
She didn’t think too much about their peculiar flashes, but by 1991, the lightning bugs’ behavior had become an obsession for the then 37-year-old Faust. Similar lightning bugs had already been documented in Asia hundreds of years ago — they were so plentiful and reliable that when they blinked in unison, sailors used them as natural lighthouses. But synchronous fireflies had yet to be confirmed in the United States.
Faust wondered if the ones from her childhood were synchronous, too, so she went to the park and then the University of Tennessee.
“I said, ‘What are these fireflies flashing together up there? They're synchronous,’ and they looked at me like I had two heads. No one knew, and no one cared,” Faust said.
Since then, Faust has proved the species was not only synchronous but that it was worth caring about. We now know that of the more than 2,000 species of firefly worldwide, the Smoky Mountains’ Photinus carolinus is one of three synchronous species in North America. That species and another, Photuris frontalis, have been documented throughout the eastern United States. The third, Photinus knulli, has been observed only in Arizona and northern Mexico.
The proper habitat for synchronous fireflies can be found in pockets across the eastern United States, but they are sensitive to light — even a full moon can disrupt their ability to flash in unison. Large swaths of untouched, dark forest in national parks provide prime habitat. Every year, between 30,000 and 40,000 people enter a lottery for just shy of 1,000 passes to see the lightning bugs over eight nights at Great Smoky Mountains National Park. A record-breaking 17,593 people entered a similar lottery in 2023 in hopes of being among the 1,300 chosen to see the Photuris frontalis species at Congaree National Park in South Carolina.
Every year, between 30,000 and 40,000 people enter a lottery for just shy of 1,000 passes to see the lightning bugs over eight nights at Great Smoky Mountains National Park. A record-breaking 17,593 people entered a similar lottery in 2023 in hopes of being among the 1,300 chosen to see the Photuris frontalis species at Congaree National Park in South Carolina.
Before the national parks implemented the lottery system, thousands of visitors arrived nightly during the synchronous display. Flashlights, headlights from cars, and people venturing off trail became a threat to the lightning bugs. While there was initial frustration from the public, the lottery allows the parks to protect the wildlife and provide a more enjoyable experience for visitors, Jon Manchester, Congaree National Park’s chief of visitor services, said.
“It's just gotten bigger and bigger,” said Manchester, who is also a park ranger. “It definitely shows how popular this event has gotten.”
Photographer Stephen Cook visited the light shows in both national parks in 2023 and understands the draw.
“The sheer number of flashing fireflies made me feel like a rock star performing at a stadium with a sea of camera flashes in front of me — or, maybe, surrounding me? I turned backward and was humbled to see the fireflies flashing not only behind me, but next to me, flying over my shoulders and above my head. I was no longer a spectating third party,” he said. “I was fully immersed — a part of nature, a being just like the fireflies.”
While scientists know relatively little about fireflies and even less about the synchronous species, there’s a small but dedicated group — including Faust — working to uncover the mysteries of lightning bugs: how they operate, where they live, and what species exist to benefit conservation. An even smaller group is studying how synchronous species seamlessly communicate with each other. The answers may be useful to the fields of computer science, physics, and medicine.
Whether you’ve seen a synchronous display or not, most of us have seen fireflies shimmer and float across our yards or captured them in jars to marvel at their beauty. They seem almost magical, and like the most famous magicians, they keep their secrets hidden.
Photinus carolinus blankets the forest in the Great Smoky Mountains National Park, where synchronous lightning bug behavior was confirmed for the first time in the United States.
Faust’s obsession with lightning bugs grew as her family’s time in Elkmont was ending. In the early 1900s, lumber companies and their workers began developing the Elkmont community, about 30 minutes south of Gatlinburg inside what is now Great Smoky Mountains National Park. They added a railroad to move goods, which unexpectedly made the area a vacation destination as well. As tourism grew, families built vacation cabins through the 1920s. By 1934, many of the owners reluctantly sold their property in exchange for lifetime leases to expand the national park established eight years prior.
In 1952, most lifetime leases were converted to 20-year leases, and finally, in 2001, the last of the leases expired.
As Faust reflected on what she would miss about living in Elkmont, she had more and more questions about the lightning bugs she loved watching every summer.
“When you're gonna lose a loved one — be it human or a place — you start noticing more,” she said. “Suddenly, it's like, ‘Oh, man, we're not gonna get to see these again.’ We were heartbroken.”
At that time in the early 1990s, her children were getting older, so she had more time to investigate the phenomenon. When local researchers didn’t seem interested in her quest, she turned to Jonathan Copeland, a behavioral neurophysiologist from Georgia Southern University, and Andrew Moiseff, a neurobiologist from the University of Connecticut, who had been studying synchrony in lightning bugs in other countries. They were intrigued by her observations and hauled their equipment in a van to Tennessee, where they spent three weeks analyzing the insects with Faust.
“They proved it with lots of computers — back when computers were enormous,” she said. “[Synchrony] had been in the literature in other species around the world, but it had been sort of a holy grail to find in North America.”
For the next 18 summers, the trio observed the synchronous species in Tennessee and, along with other researchers, identified more across the country.
“You just needed people to believe it was possible,” she said, “then everybody started finding it.”
Faust is now known as the Lightning Bug Lady (a nickname she thinks stuck after a reporter covering the synchronous display in the Smokies used it to describe her), and she wrote the first field guide for lightning bugs in the eastern and central United States in 2017. She’s expanded her focus beyond synchronous species to become one of the world’s leading firefly experts. When I spoke to her on the phone in September 2023, she was organizing field notes from her summer research and juggling the demands of interview requests for podcasts and presentations.
“It became more and more an obsession,” she said, “and then it took over my life before I realized it.”
At 69, her research and consultation work has taken her to 19 states in 2023 alone. While there are more complex things we can learn from lightning bugs, Faust said there’s still so much we don’t know about the insects themselves because they’re difficult to study — they’re small, many look alike, and they flash only briefly and in remote, dark areas during a short time each year. And since they’re not an agricultural pest or a human health problem, there’s little funding to study them.
“There's plenty left to discover. Very few people can recognize the different species, and if you can't recognize the species and no one knows where they are, then there's no way in the world we can conserve them,” she said. “It's a quest you're never going to master. You’re never going to have a chance to see every firefly out there every year — it's not going to happen — but you try to learn what you can and enjoy it.”
Here’s what we do know about lightning bugs.
Lightning bugs are on every continent except Antarctica — North America alone has more than 125 documented species. You can call them lightning bugs or fireflies, but the insects are neither bugs nor flies — they’re beetles. Most species transform from egg to larva to pupa to adult in one to three years. Adulthood lasts only a few weeks, with the majority of their life spent burrowed in loose, damp soil eating soft insects like worms and snails. Depending on the species, lightning bugs usually emerge as adults for a few weeks between May and August.
“The most spectacular part of their life,” Manchester said, “is also the last part. They go out with a flash.”
They spend their short adulthood blinking, flashing, and glowing to find a mate and lay eggs. Of the approximately 2,000 species of fireflies worldwide, not all flash, but the ones that do each twinkle in a unique way. It’s called a flash pattern. The male’s flash pattern is like a language that only females of the same species can understand. As a male flashes, it hopes a female near the ground will accept him. If she does, the female will respond with her own flash to invite the male over.
Marc Branham, a University of Florida entomology professor, has, like Faust, made a career studying lightning bugs. He is curator for the firefly family of the Smithsonian Institution’s National Insect Collection.
As a graduate student at the University of Kansas in the early 1990s, Branham was interested in studying insect communication. Since they were so common, he thought lightning bugs wouldn’t be an option for a thesis study, but an adviser encouraged him to look into what had been published already.
“I was really shocked at how little was known, and so I was instantly drawn in by studying something that is really interesting, charismatic, and not halfway around the world,” Branham said. “It’s literally right here in my own backyard.”
He built computer-controlled robotic fireflies to understand what’s most attractive to female fireflies. It was the first study on female choice among bioluminescent animals, and led to a career’s worth of questions — from how fireflies evolved to the primary function of their bioluminescence.
“They are a lot more complicated than you would like to assume sitting outside in your lawn chair,” Branham said. “That's what I think is so exciting about science — things in our own backyard oftentimes are really poorly understood. And it's not poorly understood because it's hard to figure out. It’s because no one really spent the time to dive into it. I tell lots of kids, ‘You can do this and be the world's expert, and you don't need fancy scientific equipment.’”
At Congaree National Park in South Carolina, visitors who won a lottery ticket gather on the Firefly Trail, lit by strands of the dimmest Christmas lights, to watch the lightning bugs’ display.
Even without fancy equipment, it’s easy to see how the flash patterns vary by color, speed, and duration. Watching Photuris frontalis — also known as snappy syncs — at Congaree National Park, I noticed how much more white the fast flashes seemed than the yellow-green I remember from my childhood in the Florida Panhandle. We stood on a trail — recently renamed the Firefly Trail in honor of the event — lined with a string of red, solar-powered Christmas lights that were dim enough to not disturb the fireflies and just barely bright enough to guide viewers through the dark. While the snappy syncs danced in unison, a short blue-green glow drew my attention from their performance. It was another species, a blue ghost, that, instead of flashing in quick bursts, flies and flashes so slowly that it leaves a glowing trail in the sky.
While there are hundreds of flash patterns, they’re all made possible by chemistry. Lightning bugs have special light-producing (or bioluminescent) organs that activate when oxygen is combined with calcium, producing an energy source called adenosine triphosphate, a chemical called luciferin, and a bioluminescent enzyme called luciferase. Their glow is primarily for communication; it’s also a way to let predators know they will not taste good. According to Branham, the firefly is able to regulate the amount of oxygen it uses to control the pattern and time of its flashes.
When it’s the right temperature, with the right amount of darkness, the lightning bugs begin their light show.
Unfortunately, their light show is threatened. A recent study found that we’ve lost 5 percent to 10 percent of all insect species in the last 150 years. While we don’t have reliable data now on the health of lightning bug populations, Branham said there are a few things that negatively affect them. Satellite imagery of the United States shows that there’s more light pollution from cities, porch lights, and streetlights. For lightning bugs that communicate by light, it’s much more difficult to find a mate.
Increased use of pesticides, herbicides, and fungicides in agricultural and residential landscapes affects not only pests but beloved insects like lightning bugs, too. Finally, Branham said, development threatens habitat by eliminating soil or lowering aquifer levels to the extent that soil that was once damp enough to support lightning bugs (and the insects they eat) is now too dry.
Insect population decline is especially concerning because millions of species have yet to be discovered. According to the American Museum of Natural History, scientists have named about 1.2 million insect species, but there could be as many as 3.5 million on Earth. There’s so much work left to do — and Branham said he wants to do it before more species are lost. It’s his career goal to learn as much as he can so he can pass down the knowledge but also so that it can be used to conserve biodiversity.
“I think fireflies serve as a great model organism for people to experience nature and think about how these systems are changing,” he said, “and how they might be affected by the sorts of activities we all lead.”
Orit Peleg, physicist and computer scientist at the University of Colorado at Boulder, is one of many scientists studying how lightning bug communication could have broader applications in science. She first read about the synchronous species in a physics textbook as an undergraduate student in Israel and knew she wanted to pursue research that combined physics, computer science, and animal behavior.
I spoke with her over the phone in May 2023 while she was studying the fireflies in Congaree National Park.
“Maybe if we better understand how fireflies synchronize,” Peleg said, “that can potentially help us solve any number of riddles in complex systems science.”
Complex systems science is the idea that living and nonliving behavior is made of building blocks that interact with each other, and act as a collective when put together. Examples of synchrony in living things include heart cells that contract together to pump blood, or neurons that synchronize and cause epilepsy. In nonliving things, it could be electrons that synchronize in a superconductor to reduce friction and allow electricity to flow perfectly.
Understanding how things synchronize could be part of the answer to helping us learn how to avoid traffic jams in self-driving cars, for example. Traffic can be caused by a delay in a driver’s response to situations on the road, but if we could give cars a way to synchronize with those nearby, we could possibly avoid those delays. This is a potential and long-term application, Peleg said, but an example of how this knowledge could be used.
“Basically, anywhere you look around you, there's complex systems like this, and they're very hard to study,” she said. “Fireflies are one of these accessible examples, where maybe we can learn something that can be reflected to some of these other systems.”
She compared firefly communication to computer language because it has a simple on-off system but is also complex because it’s not yet clear how they communicate with large swarms of hundreds or thousands with limited cognitive abilities.
“How could it be that they're able to synchronize their flashes throughout the swarm? That's kind of the big question that we're trying to understand,” she said.
She considered mathematical models that suggest fireflies don’t have to pay attention to the whole swarm to synchronize — they only need to pay attention to their neighbor. If all of the insects do this, eventually synchrony occurs. To prove it, her team set up multiple cameras in Great Smoky Mountains National Park to record different angles of the swarm in their natural environment. Then, they did the same in a tent, a controlled environment.
Scientists are still trying to understand synchrony in lightning bugs, but recent studies suggest that one insect pays attention not to the whole swarm but to its neighbor — eventually, like the wave at a football game, synchronous blinking occurs throughout the swarm.
Through these experiments, her team analyzed the recordings to reconstruct not only when flashes occur but also where the insects are when they flash. The findings seemed to confirm their hypothesis: Synchrony seemingly began with a few fireflies, then, like a more sophisticated version of the wave at a football game, it occurred throughout the swarm.
While their findings were considered a breakthrough, the work is not done. She and her team re-created the experiment at Congaree National Park this year and are currently analyzing their findings to learn more about firefly synchrony.
“The more people know about it,” Peleg said, “maybe we can get more people excited about understanding fireflies and getting some of these mysteries solved.”
Because their experiments use relatively inexpensive and readily available cameras, Peleg thinks her team could eventually develop a way for other researchers and citizen scientists to easily capture data, such as the species and the number of insects in one place, to help with conservation efforts.
In the meantime, Faust’s book, Fireflies, Glow-worms, and Lightning Bugs, paints a picture of what we can do to help — and see more — lightning bugs. We can reduce outdoor lighting so they’re able to find mates, avoid using pesticides in our yards, and allow undisturbed soil and native plants to grow. When catching fireflies, avoid leaving them in air conditioning or direct sunlight, and include crumpled, damp paper (unbleached coffee filters work, too) for moisture and shelter and a rinsed, peeled apple for food before releasing them no longer than 24 hours later.
Though she now spends most of her summers looking at insects scientifically, Faust thinks watching them in a lawn chair with friends is just as important because they are “an introductory drug to nature.”
“This is sort of a pure, fun insect that just brings joy and gets people back outside,” Faust said. “Everyone likes fireflies, basically — I haven't met many people that don't. It's magical.”
She’s counted at least 17 species on her 40-acre farm in Tennessee. Whether you’re watching the synchronous species flash together in a national park or the ones in your backyard twinkle like Christmas lights, she said, it’s going to be beautiful.
Jessica Bradley is a freelance writer in North Carolina interested in telling stories about nature and the problem solvers who protect it.
Stephen Cook is a Georgia-based traveler, adventurer, and photographer. By shifting his focus away from the camera gear and scene planning and toward the experiences themselves, Stephen captures genuine, candid moments of exploration and nature — scenes he hopes anybody else would be able to see for themselves.
