Fireflies (also known as “lightning bugs” in some parts of the country) were one of the bonuses I got when, several years ago, I traded my house in the city for a more rurally located home with a large, wraparound porch. On one of my first summer evenings in my new digs, I remember being delighted to find that the dark hours out here were enhanced by twinkling, natural lights.
Fireflies aren’t really flies at all but nocturnal beetles that produce a “cold” light—meaning that there’s no heat—through an incredibly efficient chemical reaction known as bioluminescence. The insects combine calcium, adenosine triphosphate and the chemical luciferin with an enzyme called luciferase in the presence of oxygen. When all these ingredients are mixed up in the firefly’s abdomen, light is produced. And every time the firefly flashes, a little more of the chemicals are mixed. The bugs light up to attract mates, communicate with each other, lure prey and warn potential predators that they taste bad.
There are some very special fireflies, however, that are real crowd-pleasers. In Great Smoky Mountains National Park in North Carolina and Tennessee, synchronous fireflies (Photinus carolinus) put on an annual summer show that draws visitors from around the world. For two or three weeks in late May and early June, the park pulsates with light and darkness orchestrated by thousands of fireflies.
Synchronous fireflies are uncommon: only three species inhabit North America, mostly living in the Appalachian regions that stretch from southern Pennsylvania to Georgia. Ground zero for the Photinus carolinus event is Elkmont, Tennessee, a former logging settlement that now hosts a campground inside Great Smoky Mountains National Park.
When the bulk of home and vacation cabin leases in the park expired in 1991, vegetation in the park grew back, creating an ideal environment for fireflies. In 1994, the synchronous fireflies were discovered. A year later, the National Park Service removed streetlights, drawing even more of the insects. They attracted so many visitors that in 2006, the park service decided to shut down the area during peak firefly season, with nighttime access granted only by a shuttle-and-lottery system. Today, would-be synchronous firefly viewers have four days in April to register for a lottery spot, with randomly selected winners announced at the end of May. To determine the exact dates of the event, a park entomologist relies on a formula that factors in the minimum and maximum air temperatures from March 1 and makes a prediction about eight weeks out. This year, 21,000 people entered to win one of the 1,800 passes (for vehicles holding up to six people) to Elkmont.
Photinus carolinus is only one of 19 species of fireflies in the park, but their in-sync flashing is extraordinary. Their glowing bodies light up in unison, blinking quickly on and off; then they pause the laser show for five seconds, everything going dark, before beaming again.
Watch the two videos below. In the first, you’ll learn about the synchronous firefly phenomenon at Great Smoky Mountains National Park. In the second, videographer Radim Schreiber captures the lights of fireflies in the woods near his house in Fairfield, Iowa. The footage came straight from his camera, he says, without any digital manipulation. I suggest that you view this video at night, with all the lights turned off, in full-screen with the sound turned up.
In my case, I’ll pretend I’m on my wraparound front porch, seeing these shining beams of light for the first time, welcoming lanterns leading me to my true home.
Here’s to finding your true places and natural habitats,