The Light Show in the Great Smokey Mountains

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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