Fireflies are nature’s light show at this West Virginia state park

Although fireflies are found on every continent except Antarctica, the flashing type primarily thrives in the humid eastern U.S. from Maine to Florida. The males attract mates with mesmerizing light displays, but only in select pockets of the Appalachian Mountains do they flash in unison.

The Elkmont region in Tennessee’s Great Smoky Mountains National Park is renowned for this spectacle, drawing crowds during the two-week mating period when Photinus carolinus synchronizes its flash pattern. These elusive beetles can also be found in lesser-known locales across Appalachia. However, an unexpected discovery emerged during a West Virginia state park’s pursuit of International Dark Sky status: another thriving population of synchronous fireflies on public land.

Discovering Watoga’s synchronous fireflies

In 2019, Watoga State Park officials and community volunteers banded together to transform the park into a dark-sky haven. Spanning 10,000 acres and surrounded by another 10,000 acres of protected forest, Watoga features some of the darkest skies in the Mid-Atlantic. Park officials and volunteers spent three years installing International Dark Sky Association-approved lighting. During the first summer of the project, a retired biologist discovered the fireflies while visiting Watoga. 

In 2020, researchers from the West Virginia Division of Natural Resources confirmed the presence of these fireflies. They looked for Photinus carolinus’ signature display—a “flash train” of six quick pulses followed by six to nine seconds of darkness—and quickly found it. “The more you looked, the more you realized that Watoga is home to synchronous fireflies everywhere if you’re there at the right time of year and walking out at the right time of night,” says Mack Frantz, a zoologist on that trip. 

Lynn Faust, the self-taught researcher who identified synchronous fireflies in the Smokies, says Watoga’s population has probably been there all along but is more clearly seen and growing due to reduced light pollution. Unlike the continent’s most common firefly, Photinus pyralis, which has evolved to court in twilight, the carolinus species requires total darkness.

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In the 1990s, while looking for fireflies at her family’s cabin in Elkmont, Faust became fed up with a streetlamp that was “messing up [her] experiments,” so she climbed the pole at 2 a.m. and smashed it with a rock. The woods “literally exploded in sparkles,” she says. “For about five seconds, the entire forest came alive with flashing.” Over the next decade, the national park removed all streetlamps from Elkmont, and Faust says the synchronous flashes immediately filled the newly darkened areas.

After the discovery in Watoga, the Division of Natural Resources submitted a letter of support to the International Dark Sky Association, ultimately helping the park achieve its Dark Sky designation in 2021. Today, Watoga, Calvin Price State Forest, and Droop Mountain Battlefield State Park make up West Virginia’s only International Dark Sky Park. It’s one of 87 in the U.S., only 22 of which are east of the Mississippi River.

Protecting fireflies from overtourism

The carolinus firefly is less researched than common species, but the IUCN Red List names light pollution and trampling as its biggest threats. In Elkmont, crowding became such an issue that the national park introduced a lottery system to protect its vulnerable beetles from too much “entomo-tourism,” as the IUCN defines it. Fewer than 1,000 out of the 20,000 to 50,000 people who apply to the lottery every spring succeed. 

Watoga has experienced a spike in tourism since the discovery of its synchronous fireflies and Dark Sky designation, with June visitation shooting up 34 percent from 2019 to 2022. “Our number one concern at this point is understanding this sensitive species,” says Jody Spencer, Watoga State Park superintendent.

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New signs around the park alert visitors to viewing etiquette: “No artificial lighting. No flash photography. Stay on designated trails at all times. Do not capture fireflies. No smoking or perfume,” and “cover up for mosquito protection” instead of wearing insect repellent.

How to see synchronous fireflies in Watoga

Watoga’s synchronous fireflies flash from around mid-June to the end of the month, though climatic conditions dictate the exact timing. As part of its conservation management plan, the Division of Natural Resources installed a weather station in the park to help track breeding phenology. 

Using this data, researchers can predict the flashing a couple of months before it begins. The state park now holds expert talks and events celebrating the fireflies and star parties every summer. 

Frantz says Watoga parkgoers don’t have to go far from their cabins or campsites to see the phenomenon. He recommends going out just before 10 p.m. to catch the show’s start. “Depending on how big and open the area is, you might see cascading effects of synchrony because those males are focused on individuals that are closer to them,” he says. “It might look almost like somebody doing the wave all around you.” Finally, after an hour or so of practice, the fireflies achieve perfect harmony.