Lightning in a Beetle: Following Fireflies in the Mon

By ,

June 25, 2024


Discovered in 2019 during Watoga State Park's International Dark Sky Designation Assessment, the Monongahela's synchronous fireflies are one of West Virginia's best-kept secrets!

Double Exposure Silhouette of Person Standing in Front of Light Sheet. The Portrait is filled with Fireflies. Text reads "Lightning in a Beetle- Finding Fireflies in the Mon

As the sun falls beneath the rolling Allegheny Mountains and a bright strawberry moon rises into view, I slowly maneuver my way up one of the Monongahela National Forest’s gravel roads in the recently restored Mower Tract. I hardly have a moment to unbuckle my seat before the descending curtain of night signals the start of the show. What begins as a few flickers of light rapidly evolves into a pulsing, bioluminescent haze stretching past the treeline of an old firetower road. Equally surreal is the line to this dreamlike scenic overlook, or the lack thereof- with over a million acres of public land across eight counties, there’s scarcely a soul for miles.

Fireflies and Stars Light Up the Night in this Long Exposure Photograph of a Forest Service Road

A fifteen-minute long-exposure illuminates the trails of fireflies and stars at the Mower Basin Trail System in Randolph County.

Opportunities to witness the midnight magic of these romantic rituals
have been dimed by the encroachment of light pollution

Among the thirty species of fireflies that call West Virginia home, one stands out for its unusual behavior. Photinus carolinus, one of only three species in North America known to synchronize their displays, has recently garnered international attention, drawing biologists and National Geographic reporters to the heart of the Monongahela. Found in isolated pockets of hardwood forest throughout the Appalachian Mountains, these firefly populations might not be at risk; however, opportunities to witness the midnight magic of their romantic rituals have been dimed by the encroachment of light pollution.

For decades, thousands of visitors have made the pilgrimage to Great Smoky Mountains National Park to see P. carolinus in action. Unfortunately, this firefly fanfare has resulted in four-hour traffic jams, necessitating the institution of a public lottery for highly coveted front-row seats at the Elkmont Campground. However, after a chance discovery in 2019, those unable to snag a seat in the Smoky’s can breathe a sigh of relief.

Fireflies glide above green grass at night

Fireflies flying in Forest

Fireflies float above flowers in field

Fireflies dance above a field of flowers at Cheat Summit Fort in the Monongahela National Forest

In Pocahontas County, West Virginia, right outside Marlinton, is Watoga State Park. At over 10,000 acres, Watoga, a former company town transformed into an independent African-American community in the early 20th century, is the state’s largest park. In a venture buoyed by its proximity to the Mon’s undeveloped wilderness area, the region’s mountainous terrain, and Greenbank Observatory’s National Radio Quiet Zone, Watoga underwent several nighttime surveys to assess its eligibility for international Dark Sky Park status. During one such assessment, a retired biologist identified the distinctive 5-to-8 flash pattern of P. carolinus, an observation confirmed by subsequent studies conducted in 2020 by the West Virginia Division of Natural Resources.

“Biologists here have even been able to identify
specific firefly families by their flashes

The discovery of P. carolinus and Watoga’s Dark Sky designation have spawned an annual synchronous firefly walk, taking visitors along a short hike that parallels a quiet stream, one of the fireflies’ favorite performance venues. During the multi-day event, volunteer biologists and park staff dispense special flashlights, whose somewhat ominous red glow emits enough light to navigate the trail safely without interrupting the beetles’ colorful courtship rituals. While the season’s most eligible bug bachelors illuminate the forest, the female fireflies lie motionless in the grass, waiting patiently for a suitor with the right rhythm. Above the thrum of an amphibian choir, a Watoga staff member shares insights into the intricacies of firefly behavior, “each species has a distinct mating pattern; biologists here have even been able to identify specific firefly families by their flashes.”

Figures walk through forest illuminated by red light

Visitors hike through Watoga State Park with special red flashlights

Fireflies, like P. carolinus, can spend years underground as larvae, subsisting on a diet of worms and slugs as they build up the energy for their showy yet comparatively short two-week display on the surface. While entomologists rely on a “degree-day” model that estimates the firefly emergence based on the relationship between insect growth and temperature, the exact timeline varies. Visitors can reliably expect to see the most brilliant showings in June; however, environmental factors such as rainfall influence their day-to-day demonstrations.

People don’t really think of moths or flies as vital parts of the ecosystem,
but they truly are the nuts and bolts that keep the machine running.”

The Mon, of course, contains more than just fireflies, and much like a moth, at the end of my walk, I am drawn to the bluish haze of UV lights strung along an upright bedsheet. Madison Fernandez, an AmeriCorps serving with the Forest Service, stands watch from the sidelines, identifying a host of beetles, flies, and moths as they arrive. While perhaps not as endearing as P. carolinus, the abundance of stoneflies, mayflies, and caddisflies is a positive sign. These macroinvertebrates, who may spend years in the surrounding clear and cool mountain streams, are especially sensitive to temperature, chemicals, and water flow, making them important bioindicators for environmental health. While these nymphs must have dined well on detritus and algae, the less fortunate serve an equally vital role as tasty snacks for the region’s native Brook Trout and the critically endangered Candy Darter. Pointing to a gigantic Polyphemus moth, Fernandez notes, “People don’t really think of moths or flies as vital parts of the ecosystem, but they truly are the nuts and bolts that keep the machine running. They are the base of the food web, pollinators working thanklessly throughout the night. The next time you take a nighttime walk or glance at a porch light, I encourage you to acknowledge the insects; they do so much more than people give them credit for!

Volunteer motions to point out insects on light sheet during demonstration

Monongahela National Forest AmeriCorps Madison Fernandez highlights local insects at a light sheeting event in Watoga State Park during the annual Dark Skies Synchronous Firefly Walk.

Whether you’re exploring Watoga or hiking in the wider Monongahela forest region, you don’t need to be an entomologist to contribute to scientific research. The West Virginia Division of Natural Resources’ Light Up‘ citizen science campaign, accessible through a simple app on your phone, invites you to record your sightings of lightning bugs and glowworms across numerous state parks, forests, rail trails, and wildlife areas. Visitors can also download the WVDNR identification guide here!

Graph of common fireflies flash patterns.

Common firefly flash displays (Photo Courtesy of NPS)

Although I won’t be putting any of these unique insects in a jar, I have certainly caught the lightning “bug.” Since my first encounter with this season’s show, I have spent nearly every night in the national forest and adjoining state parks, taking in the enchanting swirls of light, a lover’s dance 100 million years in the making.

Fireflies above creek and cut grass in park

A long exposure at West Virginia’s largest state park reveals the complex light trails left by several species of bioluminescent bugs on the search for love above a small creek during the annual firefly walk.

Firefly Finding Tips:

➤ Avoid using flashlights and bright phones when searching for fireflies. In addition to making them harder to see, artificial light has been shown to disrupt their mating rituals.

➤ Be careful where you step! As female fireflies remain on the ground, it’s important to stay on gravel-lined trails if possible.

➤ The best place to look for fireflies is in open fields along slow-moving bodies of water. They can also be found in the forest, but in my experience, they are less numerous in the deep woods.

➤ Be patient! Different species prefer varying levels of darkness before starting, and P. Carolinus prefers complete darkness, meaning it may take a few hours for them to synch up! While displays usually go on for around 3 hours, I have seen demonstrations go from 9:00 PM to 3:00 AM

➤ Fireflies will pack up for the night if the weather is too cool (below 50F) or too rainy. While I’ve seen a few brave bugs perform before an advancing thunderstorm, be sure to check the weather before you head out to maximize your chances of seeing them.

➤ Remember to practice Leave No Trace principles when visiting the National Forest to preserve these unique habitats for generations to come!