Are there more fireflies in Pennsylvania this summer? Here’s where to see them near Philly

Photuris pensylvanica — better known as the Pennsylvania firefly or, as most Philadelphians call it, the lightning bug — is out in full force this summer.

Reports suggest that central and rural parts of the state are seeing a surge in sightings of the glowing beetles. That’s likely because they thrive in warm, humid weather, said John Tooker, an entomologist at Penn State. An Inquirer analysis found that Pennsylvania summers have become increasingly warm and wet in recent years — ideal conditions for fireflies to light up.

Fireflies typically emerge around the summer solstice in mid-June and fade out by late July. But while their presence may feel more noticeable, that doesn’t mean there are more of them. Tooker said the Pennsylvania firefly population has remained steady — not growing, but not shrinking either.

Pennsylvania’s fireflies are considered “generalists,” meaning they can adapt to various environments. Others aren’t so lucky. Other species of fireflies are heavily hit by ecosystem destruction.

There are still a few weeks left to catch lightning bugs in the region, before their glow dims for the season — and with it, the nostalgic summer tradition of chasing them around your backyard.

Despite the name, fireflies are beetles — not flies. They live in tropical and temperate regions, like Pennsylvania, and produce a glowing light thanks to a chemical reaction in their abdomen.

Pennsylvania is home to about 30 firefly species, each with its own unique flash pattern to help them attract mates. Their glow can also warn predators of their bitter taste (though frogs, apparently, don’t mind — and may even end up glowing themselves after a firefly-heavy snack).

They’re completely harmless to humans, but don’t let your pets snack on lightning bugs. Ingesting a firefly won’t be life-threatening for a dog or cat, says the ASPCA, but for lizards, ingesting even small amounts of lightning bugs can quickly cause severe health issues or death.

Fireflies love open meadows near woods or water — think streams, ponds, or rivers. That kind of habitat isn’t abundant in most of Philadelphia, but you can still spot them in well-maintained backyards with native plants, said Tony Croasdale, an ecologist with the city’s Department of Parks and Recreation.

“I think online trends are making people more aware of allowing your garden’s vegetation to grow and planting more native plants to attract native insects,” Croasdale said.

The more diverse, native vegetation you have in your yard, the more insects will come. Tooker notes that fireflies won’t necessarily come due to plants as they don’t feed on them, but a biodiverse backyard draws more insects, which in turn may bring in lightning bugs. To boost your chances, reduce artificial light and pay attention to flash patterns.

“Watch the ones flying in the air — they’re the males — and they tend to sweep in a J-shape when they are flashing their lights. Then, scan the ground and see if you can find any of the females down low," he said. “You can see the females doing their little flashing down there because they’re trying to respond to males that they find attractive.”

For a more advanced challenge, Tooker says to try and identify different firefly species by their flashing glow patterns.

The Wissahickon Environmental Center is one of the best spots in the city to see lightning bugs. It’s hosting a “Campfire and Firefly Evening” on July 17 at 8:30 p.m., where attendees can roast s’mores and learn about these fascinating creatures.

Once you’re outside the city, it’s not hard to spot fireflies along dark country roads or open fields. But if you’re staying local, these Philly-area spots offer some of the best viewing:

Note: Some parks, like Bartram’s Garden and Valley Forge National Historical Park, close at nightfall — so check their hours before planning your visit.