The Great Smoky Mountains' Incredible Firefly Light Show

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Today, the rare Smoky Mountain fireflies are a tourist attraction. Twenty years ago, science didn’t believe they existed.  

At exactly 9:27 P.M., when dusk slips into darkness in the Great Smoky Mountains National Park, the “light show” begins. It’s June, and for two weeks in Elkmont, Tennessee, the fireflies pool their efforts. Instead of scattershot blips of light in the summer sky, the fireflies—thousands of them—pulse this way for hours, together in eerie, quiet harmony. It’s as if the trees were strung up with Christmas lights: bright for three seconds, dark for six, and then bright again, over and over. It continues this way for hours.

As a child, Lynn Faust would huddle with her family on the cabin porch to watch the spectacle. They’d sit, mesmerized by the “drumbeat with no sound.” And though they’d appreciated the show for generations, Faust never thought the event was newsworthy. “I’d assumed there was only one kind of firefly and thought they did a nice show in the Smokies,” she says.

The natural world has long enchanted Faust. In college, she majored in forensic anthropology and minored in forestry. In her twenties, she circumnavigated the globe for three years, visiting islands you could only get to by boat, learning about cultures before they disappeared, pursuing underwater photography. Today, at 60, she’s a naturalist who writes scientific papers and field guides about fireflies. But she wasn’t always obsessed with the insect. In fact, her academic interest began only in the ’90s, when she read an article by Steven Strogatz, a Cornell mathematician, in which he marveled at a species of Southeast Asian firefly that synchronized its flashes. Highlighting how rare this phenomenon was, Strogatz noted that there were no synchronous fireflies in the Western Hemisphere.

This struck Faust as odd. It contradicted the light shows she had seen growing up. As she dug deeper, Faust found that while there had been more than 100 years of colloquial accounts of North American fireflies flashing in sync, scientists discounted those reports, attributing them to lore or optical illusion. Faust knew the truth: that her Tennessse fireflies were every bit as special as the species in Asia. But how could she prove it?

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Fireflies—or lightning bugs—may be the closest thing nature has to a magic trick: lighting the world from the inside out. Technically, they are bioluminescent beetles. Their glow comes from an internal chemical reaction that combines oxygen and calcium with a series of enzymes, including a key light-producing one called luciferin. The bugs flash for lots of reasons: to communicate, to attract mates, to scare off predators. But for creatures so striking, they’re also common. There are roughly 2,000 species worldwide and 125 or more in North America alone, where catching them is a childhood rite of passage.

More than 20 years ago, Faust wrote a letter to Strogatz after reading his article. He connected her with Jonathan Copeland, a biologist and professor at Georgia Southern University who was studying firefly behavior in Malaysia and Indonesia. Copeland was skeptical of Faust’s tale. Reports of synchrony had crossed his desk before but had never panned out. “The dogma said they do not synchronize in North America,” he says.

Still, he indulged Faust, asking her to describe what she’d witnessed by drawing a “musical score.” As a child, Copeland, a tuba player, dreamed of playing with the Boston Symphony. Ever since, music dominated his approach to the natural world. In grad school, he’d studied and documented the rhythmic lunge and strike patterns of praying mantises. He took a similar slant on firefly behavior and found that if people charted the synchronic rhythms they were witnessing, he could separate a bogus account from a real one. Putting pencil to paper, Faust was nervous. “To look at it scientifically is very different from sitting in your rocking chair with a blanket and enjoying it,” she says. “I didn’t want to sound like a complete idiot.”

When her note arrived, “it looked like synchrony on paper,” says Copeland. In June 1993, he was intrigued enough to make the eight-hour drive to Elkmont. He pulled into the cabin’s driveway as dusk fell, no trace of the insects to be seen, and promptly fell asleep—only to wake up to flashes of light all around him. “It was completely obvious—no doubt about it!” he remembers. He rushed to find a pay phone to call his colleague Andy Moiseff. “It must have been about midnight,” he says. “I said, ‘Andy, Andy, you’ve got to see this, they’re flashing synchronously!’ Andy laughed and said, ‘Prove it,’ like any good scientist.” The following summer, that’s exactly what Copeland, Faust, and Moiseff, a professor of physiology at the University of Connecticut, set out to do. It was an unlikely partnership, but the trio made a formidable team. Copeland is a neuroethologist—he studies the neural basis for animal behavior. Faust, an unflappable outdoorswoman and keen observer, knows the area and its wildlife like home. And Moiseff is a computer whiz, with a proclivity for dreaming up theories and building devices to test them.

The three hauled lab equipment, microscopes, video cameras, computers, and insect specimens to sites throughout the Smokies. They started in Elkmont but quickly branched out to determine how widespread the phenomenon was. They hauled bugs back to the lab to do frame-by-frame analyses of the flashes. In the wild, “they were obviously in sync,” Copeland says. But when they repeated the test with individual fireflies in one-gallon freezer bags, the behavior changed. If an insect couldn’t see another, they no longer flashed synchronously. By 1995, the team had the data they needed.

“This was red-hot news in the firefly community,” says Copeland. There are four synchronous species of firefly known in Asia, and they are smaller than the team’s species, Photinus carolinus. “Their flash is wimpy in intensity, but what they lack in flash intensity, they make up in numbers,” Copeland says. They usually remain stationary in trees along the river, unlike carolinus, which fly around in the woods. “Ours are more complicated,” says Faust.

Proving synchrony existed in fireflies in the Western Hemisphere was exciting, but it raised questions about why they flashed this way. And how was that different from what their cohorts did in Asia or, for that matter, from the way their asynchronous relatives behaved in North America and even elsewhere in the park? For the next two decades, Copeland and Moiseff would study the fireflies with Faust each summer, determined to understand these magical creatures. But just as they were getting close, everything in Elkmont changed.

In the beginning, the team had the woods to themselves. “In the old days, there would be the three of us and the odd stranger who was fishing,” says Moiseff. In fact, when Faust first informed park officials about the light show, they didn’t believe her. In 1992, her family had to give up its cabin when the government took control of the resort community’s leases. By then, Faust had noticed that the firefly behavior seemed to be localized: The light show didn’t appear to be taking place even half a mile away from this settled location. She hypothesized that the synchronous behavior could be linked to the unusual conditions near the homes. But when she pointed it out, parks officials assumed her claims were a trumped-up attempt to keep her cabin.

Finally, in 1996, park administrators sent a ranger to the researchers’ campsite to investigate. “It was a funny night,” Faust recalls. “We had this ancient computer set up on the porch and Christmas lights strung across the hill to see if we could control the rhythm of the firefly flashes with the lights going off and on. He was like, ‘Where are they?’ And suddenly, there they were. The guy goes, ‘Oh, my God.’ He said that about six times,” says Faust. The next night they had 20 rangers watching.

By the early 2000s, word had spread. According to one of the park’s supervisory rangers, Kent Cave, “There were fender benders, road rage, crowds of people.” The Smoky Mountain fireflies had become a bona fide tourist attraction. In 2006, the park instituted a trolley service from a parking lot to the viewing area for peak nights, closing access to individual cars. “People were driving up. They might have driven five hours from Alabama or down from Lexington and couldn’t get in,” says Cave.

Today, tourists reserve parking spots in advance online. After the year’s peak firefly emergence has been predicted, reservations for the June viewings go live in late April. The spaces go in minutes. The light show has become the biggest of the park’s special events, with as many as 12,000 attendees in recent years. But as Cave puts it, “Our biggest headache is predicting when these little buggers are gonna flash.” There’s a system for that too. “The pressure of me telling people when to come see the fireflies began 20 years ago,” Faust says. “Like anything in nature, it’s not entirely predictable, but I’ve developed a mathematical way of figuring it out.”

Today, park entomologist Becky Nichols relies on Faust’s degree-day model to determine when the fireflies will emerge. The equation is specific to Photinus carolinus and relies on temperature data Faust and Nichols begin collecting in early March. “You take the high and the low temperatures and plug them into a formula to figure out the larvae’s accumulation of growth,” explains Nichols. “The issue in the past was that we didn’t have good temperature data.” Tiny temperature loggers fixed to trees for air temperature and to the ground for soil temperature have remedied that problem. Faust has her own data logger down the road as well, and the two women compare results as the numbers climb, hoping to come up with the same prediction independently.

Though they’re gratified that the public appreciates the light show, its popularity is bittersweet. The event is too crowded for the scientists to continue studying at the site, so they’ve decamped to other areas in the Appalachian Mountains. As Copeland says ruefully, “We can’t work there anymore because it’s a tourist attraction, and we’re largely responsible for that.”

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So why do Photinus carolinus flash together? No one has quite figured it out, Faust says. But there are theories. In a 2010 paper published in Science, Moiseff and Copeland suggest that synchrony keeps the female firefly from getting confused when searching for a mate. In an experiment using an electronic simulator with light-emitting diodes, they found that uncoordinated stimuli—too many lights coming from too many places at different times—inhibited the female firefly’s response. When flashes were coordinated, the females could clearly send their messages back to the males. Faust agree that synchrony in carolinus is related to mating.

Moiseff, who’s most interested in the firefly’s brain and nerve cells, wonders what it is about the insect’s eyes that helps it process information. Some data has shown that under the right circumstances, a firefly can determine where a flash is coming from. What this could suggest, he says, is that the insect’s brain might break information into different pathways for processing—something that primates and people do, but we don’t think of bugs doing. It’s a problem he’s still studying: “How does a simple nervous system accommodate that? What’s the mechanism?”

Moiseff also points out that Photinus’s synchrony is important not because the phenomenon is so rare but because it changes our perspective on the many ways in which living things interact. With just one proven case in the U.S., the gates opened wide for discovering others. In 1998, Copeland and Moiseff showed that a species on the Georgia and South Carolina coast, Photuris frontalis, was also synchronous. Additionally, the species Photinus pyralis, Copeland says, is “weakly synchronic.” Once you find other species doing this, “all of a sudden they’re not a freak of nature. Instead, they have a solution to a specific environmental need,” says Moiseff.

The last few years, Moiseff and Copeland have kept their firefly studies closer to home. “For the first 10 years, my spouse was very supportive,” says Copeland of his work in Tennessee. “Then she started asking questions about the significance.” He retires from his position at Georgia Southern this year, and, joking aside, considers identifying Photinus’s synchrony to be one of the highlights of his life. “I grew up as a suburban kid afraid of the dark, and I found myself [alone] in the woods with fireflies,” he says. “Serendipity—and a mind set that gets you away from cable TV—plays a role in science.”

Faust, for her part, is still involved with fireflies. She’s working on a field guide that will include images from her collection of more than 60,000 photos. And her family cabin still stands proudly in the same spot where she first saw the light show. But it isn’t quite the same. The cabin now belongs to the park, and she and her family no longer curl up on that porch under thick blankets, waiting for the pulsing spectacle to begin. One thing hasn’t changed, though: No matter how many times Faust has seen the show, Photinus carolinus’s return each summer is still a thrill. “The biggest kick is trying to predict the first night,” she says. “To see that first one and think, ‘Wow, that happened again.’”

This story originally appeared in an issue of mental_floss magazine. Subscribe here.

Could Gigantic Coconut Crabs Have Played a Part in Amelia Earhart’s Mysterious Disappearance? At Least One Scientist Thinks So

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Amelia Earhart's disappearance during her attempt to fly around the world has captivated historians and conspiracy theorists for more than 80 years. One organization is now suggesting that her fate may have been sealed by giant crabs.

The International Group for Historic Aircraft Recovery (TIGHAR) believes that Amelia Earhart and navigator Fred Noonan may have landed their plane on Nikumaroro Island when they couldn't find their target, Howland Island, and that Nikumaroro's endemic crustaceans may have played a part in the ensuing mystery.

According to National Geographic, there are several clues supporting TIGHAR's theory. The large reef that hugs Nikumaroro’s coast makes it conducive to emergency aircraft landings. In 1940—just three years after Earhart’s disappearance—British colonists found 13 human bones beneath a ren tree on the island and shipped them to Fiji, where they were lost. The colony's administrator, Gerald Gallagher, sent a telegram back to England positing that it was Earhart’s skeleton. Then, in 2001, researchers uncovered U.S.-made artifacts around the ren tree including a jackknife, a woman’s compact, a zipper, and glass jars. The plot thickened even further in 2017, when four forensic bone-sniffing dogs all indicated that a human had indeed died at the site, though excavators failed to dig up any more evidence.

If those 13 bones beneath the ren tree did belong to the unfortunate castaway, where are the rest of her remains? Tom King, TIGHAR’s former chief archaeologist, thinks that coconut crabs can answer that question.

Nikumaroro is home to thousands of the colossal creatures, which can grow to a terrifying 3 feet across and weigh 9 pounds. They’re sometimes called robber crabs because of their penchant for absconding with objects that smell like food, and they’ll eat practically anything—coconuts, fruit, birds, rodents, other crabs, their own discarded body parts, and carrion.

It’s not unreasonable, then, to think that coconut crabs may have feasted on Earhart’s corpse and then taken her bones home with them. In one experiment to test the theory, TIGHAR researchers deposited a pig carcass on the island and filmed the aftermath. With the help of small strawberry hermit crabs, coconut crabs stripped the pig down to the bone in two weeks. After a year, some of the bones had been dragged 60 feet from the carcass’s original location, and some were never recovered at all.

King believes Earhart’s missing 193 bones could be hidden in the burrows of various coconut crabs. As in the pig experiment, crabs may have scattered some of Earhart’s bones dozens of feet away, but maybe not all of them—after all, the forensic dogs smelled bones near the ren tree that haven’t yet been located. Right now, TIGHAR is working with the Canine Forensics Foundation to further explore the area.

While we wait for more answers, dive into these other theories about Earhart’s disappearance.

[h/t National Geographic]

The Cat Sanctuary That Sits Near the Ancient Roman Site Where Julius Caesar Was Murdered

ClaireLucia/iStock via Getty Images Plus
ClaireLucia/iStock via Getty Images Plus

Cats will sleep anywhere—even in ancient ruins. Located in Rome, Colonia Felina di Torre Argentina is a cat sanctuary on the site where conspirators stabbed Julius Caesar 22 times outside the Theatre of Pompey, on March 15 44 BCE. Centuries later, in 1929, Mussolini excavated the area to reveal four temples that are 20 feet below the street level. Today, it’s the oldest open-air spot in Rome.

Bystanders can view the temple complex known as Largo di Torre Argentina from the fenced-off street, but according to Conde Nast Traveler, after a $1.1 million restoration process, the sanctuary will open to tourists in the second half of 2021. For now, the only living things allowed in the sacred area (area sacra) are feral cats.

According to Colonia’s website, they are "the most famous cat sanctuary in Italy” and also the oldest in Rome. Many of the cats fall into the special needs category: Some are disabled, missing part of a paw, or are blind; the special needs and elderly cats live in a walled-off area. Volunteers—a.k.a. gattare, or cat ladies—take good care of them, and some cats are available for adoption.

Atlas Obscura reports that “since the mid-1990s, the population has grown from about 90 to a peak of 250” cats and notes that the sanctuary has a spay/neuter program. From the street, visitors can watch gatti like the three-legged Pioppo and Lladrò—known as “poisonous kitten” because of how angry he was when he got there—sunbathe and sleep under pillars.

It’s unclear if the cats are respecting Caesar or disrespecting the fallen leader. However, a gift shop is open to visitors, and people can donate money toward the cats and/or volunteer.

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