West Virginia University insect tracker says light pollution threatens rare fireflies

MORGANTOWN, W.Va. — While rare “synchronous fireflies” are becoming a tourist attraction across Appalachia, a West Virginia University researcher is reminding visitors to enjoy the spectacle responsibly and without disrupting the insects’ delicate mating rituals.

Synchronous fireflies (Photinus carolinus) are known for their remarkable ability to coordinate their flashes of light in unison, a natural wonder that draws tourists each year to places like Watoga State Park in southern West Virginia.

Nellie Heitzman, a graduate student in entomology at the university's Davis College of Agriculture and Natural Resources in Morgantown, said the phenomenon is more than a light show: it’s a vital part of the species’ reproductive behavior.

“The synchronous firefly species, Photinus carolinus, has a unique behavior in which the males cooperate to amplify their flash pattern, and the females respond with their own,” Heitzman said.

“This behavior may be due to the importance of mating with the same species because a mistake means lost time and resources, as well as potential predation by other species.”

The synchronized display typically begins around 10 p.m., when a few males start flashing five to eight times in succession, followed by about eight seconds of darkness. By 11 p.m., more males join in, creating a rhythmic, collective glow that pulses through the forest.

Because fireflies communicate through light signals, Heitzman cautioned that flashlights, car headlights, and phone screens can interfere with their mating patterns.

“Any additional light may disrupt their pattern,” she said. “They are less sensitive to red light, so visitors should use a headlamp with a red light setting or cover white lights with red film.

"Sound can also cause irregularities, so it’s best to remain quiet and stay on designated paths — the females are often in the vegetation signaling to the flying males.”

Adult fireflies live for only about two weeks, and their emergence — typically from early June through July — is staggered based on temperature. Populations at lower elevations tend to appear first.

The insects prefer humid, dark, forested environments with temperatures above 50 degrees Fahrenheit and often gather near water sources, where reflected flashes may enhance mating success.

Heitzman added that protecting firefly habitats is crucial for future generations.

“While the season’s adult fireflies are in the mating stage, the larvae dwell in the soil for two years before emerging,” she said. “It’s very important not to disturb the soil in the areas they inhabit.”

Light pollution is a growing concern in West Virginia

In addition to fireflies, West Virginia is gaining attention as a haven for star-watchers, quiet‐life seekers, and those looking to escape the neon glare of urban living. With its deep valleys and limited light pollution, the state offers some of the darkest night skies on the East Coast.

The promotion from the W.Va. Department of Tourism, in partnership with the International Dark‑Sky Association, highlights dark-sky getaways among the state’s natural assets.

The designation of parks such as Watoga State Park, Calvin Price State Forest, and Droop Mountain Battlefield State Park as International Dark Sky Parks further cements the state’s credentials.

The threat of light pollution in West Virginia

The economic opportunity is clear: “Astro-tourism” — visitors travelling for stargazing and dark-sky experiences — generates overnight stays, lodging revenue, meals and local spending. The National Park Service reports that dark-sky–driven tourism can significantly boost local economies.

Meanwhile, real-estate professionals note that the intact darkness is a sellable amenity for those migrating from bright cities.

Despite its strong position, West Virginia faces headwinds. Light pollution — the upward and sideways spill of artificial outdoor light that washes out stars and disrupts ecosystems — is quietly eroding the state’s dark-sky advantage. Analysts warn that rising ambient night glow not only diminishes the visitor experience but can also depress property values.

If the darkness fades and fireflies decrease their displays, so could the premium the state currently enjoys. Local communities are encouraged to adopt outdoor-lighting best practices, such as shielded fixtures, warmer color-temperature lighting, timers, and zoning codes, to preserve the night environment.