It’s firefly season in the Blue Ridge.
As the sun goes down, they begin to blink and glow along the water, in the trees, and across open fields. Some species twinkle in unison, others off and on. One of nature’s loveliest light shows enchants onlookers of all ages, especially in the Smoky Mountains, which is home to about 20 percent of the 100 or so species found in the United States.
But many of those who have long delighted in this essential feature of a humid East Coast summer say something feels different. Casual observers and scientists alike are seeing fewer fireflies, and studies show that habitat loss, rising temperatures, light pollution, and drought threaten these beloved bugs. Some populations are already dwindling, including about 18 species in the U.S. and Canada.
“We’ve been hearing anecdotal reports of fireflies’ population declining for years,” said Sarah Lower, a biologist at Bucknell University. “Every time I would go out and give a scientific talk somewhere, somebody would raise their hand and say, ‘You know, I’ve been out in my yard and when I’m with a kid I remember there being fireflies everywhere, now I don’t see them.’”
Lower and Darin J. McNeil, a wildlife ecologist at the University of Kentucky, examined firefly population patterns last summer, using citizen science data collected nationwide to draw connections with environmental conditions.Though their observations don’t specifically confirm a decline, they suggest reasons we might be seeing fewer fireflies in some places.
Climate change is already reshaping the Southeast with hotter, drier summers — conditions that could push fireflies past their limits. In some wetter regions, though, they may find new habitat. McNeil said these changing patterns are impacting firefly populations already.
“They’re very, very sensitive to temperature and weather and things like that,” McNeil said. “In Southern areas where we expect it to get quite warm — and maybe get outside the comfort zone of fireflies — we might expect the fireflies are going to do poorly.”
Fireflies are carnivorous beetles. They don’t live long, and spend two years of their short lives in the soil as larvae, hunting slugs and other moisture-loving critters. “Disrupt that access to the soil, McNeil said, “and fireflies disappear very quickly.”
The insects thrive in woodland areas (and, oddly, on farmland, despite herbicides), and habitat loss poses a threat. “We have this effect of fragmentation where people are chopping up the forest into little chunks and then the forest that’s left behind doesn’t get managed in any way,” McNeil said.
McNeil would like to see researchers study how forest management, including prescribed burning, impacts fireflies. In the meantime, there’s a lot that ordinary folks can do to help them thrive.
In western North Carolina, Brannen Basham and Jill Jacobs have built their lives around native landscapes. Their small business, Spriggly’s Beescaping, teaches people about pollinators — and increasingly, fireflies. The pair have a seemingly endless knowledge of fun facts about lightning bugs.
“One random interesting fact is that these animals never stop glowing,” Jacobs said. “They’re glowing as little eggs, even.” And one of the most common front yard genus, Photuris, use their glow to lure nearby males — then eat them.
They take firefly conservation seriously, running regular workshops to teach people how to make their yards more welcoming to fireflies and pollinators, particularly as climate change disrupts growing seasons.
“Fireflies might enter into their adult form and find themselves emerging into a world in which their favorite plants have either already bloomed or they haven’t bloomed yet,” Basham said. “By increasing the diversity of native plants in your space, you can help ensure that there’s something in bloom at all times of the growing season.”
Basham and Jacobs have a few other tips for helping fireflies thrive. You don’t need to be a scientist to help protect fireflies. In fact, the biggest difference comes from how we care for our own backyards. Here are a few things Basham and Jacobs recommend:
- Turn off your porch lights. Fireflies are incredibly sensitive to artificial light and it can confuse them.
- Ditch the manicured lawn and embrace native plants. In addition to being easier to care for, they suit the local environment and conserve water.
- Leave some leaves behind when you rake in the fall. They’re a great place for fireflies to find food, stay cool, and lay eggs.
- Plant shrubs, tufting grasses, and other, large plants. These can shelter fireflies during rainstorms and other severe weather.
- If you spot fireflies, jot down when and where you saw them and add your observations to citizen science databases like iNaturalist, Firefly Watch or Firefly Atlas to help scientists collect data.
Even among those who study fireflies, the thrill of spotting them remains magical. Lower has made many excursions to the southern Appalachian mountains to find the famous, ethereal “blue ghosts.” Rather than flicker, the insects emit a continuous bluish-green glow. “You walk into the pitch black woods and at first you can’t really see anything right because your eyes are getting used to the darkness,” Lower said. “But eventually you start to see all these dim glows.”
On other nights, Lower has seen so many fireflies it felt like she was walking among he stars. She’s been lucky enough to witness a phenomenon called spotlighting, in which lightning bugs hover in a circle of light. She’s even used pheromones as a tactic to lure them out of their hiding spots in the dead of winter, feeling elated as the creatures drifted toward her: “You can imagine me dancing and yelling and screaming in the forest.”
