Video highlights the sounds of summer with peepers and green frogs
Aaron Capouellez, founder of PA Woods and Forests and creator of Frog Week conservation project, talks about spring peepers and greens frogs.
- Residents are encouraged to turn off outdoor lights in June to help fireflies, which use their glow to attract mates.
- To create a firefly-friendly habitat, experts suggest leaving leaf litter, reducing mowing, and allowing some grass to grow tall.
- A new citizen science project, the Clarion County Firefly Blitz, is collecting data on local firefly populations.
Fireflies are starting to emerge across the state in advance of an upcoming state festival and a citizen science data project revolving around lightning bugs.
“So far it’s tracking right on the average, I think, just maybe a little bit above average,” firefly expert Peggy Butler said about her expectations for the glowing insect’s population this summer.
“We had what I would say was an early spring but then the temperatures cooled and it’s more in the average range at this time. We’re expecting peak season to be around the 21st of June.”
Butler and her husband Ken are cofounders of the Pennsylvania Firefly Festival, which will be held June 26 and 27 at the Market Village in Tionesta.
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“It should be really good viewing for that week, the 21st through July 1 as long as the temperatures stay in the normal range and it doesn’t go one way or the other too rapidly,” said Butler, who is also the festival’s treasurer.
The area does need some rain to attract the bugs.
“They like it hot and humid. As soon as it gets hot and humid, I think we’ll start seeing fireflies,” she said.
Some people call fireflies lightning bugs.
“It doesn’t matter which term you use,” she said. “Lightning bugs are fireflies. Not all fireflies are lightning bugs, but all lightning bugs are fireflies. You can use either term. It all depends on where you grew up and what your knowledge level is about them.”
There are numerous species of fireflies, and she’s already been seeing some spring tree-top flashers since Mother’s Day. “I think May 19th was my first firefly sighting for the season, but the synchronous fireflies typically don’t start until June 10th or 12th and with a peak being around the summer solstice,” she said.
She recently spotted a Chinese lantern firefly and said that species overlaps with the synchronous species.
“He was a little early, but he’ll have friends popping up here any day now, especially with the temperatures warming up,” Butler said.
The evening displays can be impressive to watch as each species has its own flash pattern.
“We have over 30 species in Pennsylvania. And at any given time, you may have 12 to 15 different species in a habitat, if it’s a great habitat,” she said.
The common eastern firefly comes out at dusk. The species stays active for about 45 minutes before returning to the grass. Then other species emerge about an hour after dusk when it’s truly dark.
“Those are synchronous fireflies that we see in the forest,” she said.
If the weather is warm and humid, some species will glow throughout the night until dawn.
In mid-summer, the heebie-jeebie fireflies emerge.
“We call them Christmas in July. We get them in mid-to late July and they just cover the trees, and they look like a Christmas light show going on. They are not synchronous, but they seem to have this pulsating show going on,” she said.
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Why fireflies glow
The glow of a firefly is used to attract other fireflies to mate.
Fireflies use their enzymes to create a cold light on the lower part of their body.
“Which is unique. Most of the time, when you think of light being produced by things like fire or other kinds of heat sources,” Michael Skvarla, assistant research professor of arthropod identification at Penn State University, said in a July 7, 2025, interview for this publication.
“Fireflies are unique because they can do it without producing heat,” Skvarla said.
That process is now associated with products we use, like glow sticks.
“The light that they produce is often species specific, the flash patterns. And so, the kind of classic one is the J-shaped pattern that people will see in their yards, that species likes to fly in open fields above short grass. So people will be familiar with that pattern, but most species have a unique flash pattern where they’re flashing,” he said, including areas with fields, trees and swamps.
The flashing patterns help the fireflies tell each other apart when searching for a mate.
Butler enjoys the unique qualities of these glowing insects and what they mean to the environment and changing seasons.
“It’s just another part of the season that shows that everything is in balance, everything is as it should be. So, if you have fireflies, they are an indicator species, it means everything is in balance and the habitat is free of pesticides and light pollution and that it’s natural,” she explained.
“If you don’t have fireflies, and you should in Pennsylvania, there’s reason to be concerned. Something is out of balance, whether it’s a manmade thing or some other reason. It can be a natural thing, too, like a fire, a forest fire can disrupt them. A flood can definitely disrupt them. But generally, if you don’t have fireflies, it’s something manmade or caused by human impacts.”
Lights off in June
June is the month for the conservation initiative Lights Out for Lightning Bugs, as the insects prefer dark areas.
“The easiest, quickest and most impactful thing people can do is turning off their outdoor lighting at night, specifically during June. For most fireflies, that’s their typical peak season of mating,” she said.
The flying insects prefer darker areas where they can be seen by other glowing bugs.
Making a home for fireflies
Lightning bugs prefer taller grassy areas that have leaf litter from the previous fall. The females lay their eggs in the ground and the larva can live there up to two years feeding off slugs and snails in the ground. “If you have a garden, it’s a good thing to have firefly larva in your garden. They need moist, shaded areas to keep their larva alive,” Butler said.
“Leave your leaves, turn off your light and let your lawns be natural. If you can, grow a little natural area in your backyard. Let it grow to full length and you’ll see more fireflies. Otherwise, reduce your mowing as much as possible and mow at a really high level, no shorter than four inches if possible, and try to reduce mowing as much as possible,” she said.
If you are concerned about ticks, she suggests having the taller grass natural area away from your home in an area where you don’t normally walk.
Firefly festival
The 14th annual festival in Forest County is operated by a group of board members across Pennsylvania who are involved in music and science.
The June 26-27 event has been moved from the Kellettville Campground to the Market Village in Tionesta.
“They invited us to come and host the festival there and we decided it would be great for our exhibitors to have more exposure to the public than they were getting down here in Kellettville when we were just limiting it to the evening and just ticketed tourists,” she said.
From 12 to 6 p.m. those two days, the public is welcome to visit a variety of exhibits and entertainment. “It is all free and open to the public,” she said.
However, there will be information available in the Market Village at the festival’s tent for self-guided night-time opportunities.
“We will show them some areas in Forest County where they can go and look for fireflies on their own, either that night or at another time. They are public areas that have ample parking, are safe and not lit up,” she said. “But they will be able to see fireflies at those locations.”
The nighttime programs and guided firefly events at the Army Corps of Engineers’ Tionesta Lake Recreation Area are already sold out.
Community science project with fireflies
The festival organizers are expanding their educational outreach to Clarion County.
“We love that people come to Forest County, but we aren’t the only county in Pennsylvania with fireflies. But we need more data and we need more public places that can handle the tourism and won’t impact the habitats of fireflies by too many humans going there,” Butler said.
Right now, they are looking for locations and populations of fireflies in the neighboring county.
“We know they have fireflies but there isn’t a lot of good survey data on them,” she said.
They are looking for the public to report sightings of fireflies in the Clarion area through a new project.
“We are encouraging people to participate in the Clarion County Firefly Blitz,” she said. People who want to be community scientists for fireflies can reach out to Butler by email at pafirefirelyfestival@gmail.com or the pafireflyfestival.org webpage.
“We encourage it to be Clarion County residents or people who camp regularly in Clarion County who are not necessarily residents, but weekend and holiday campers,” she said.
It’s a pilot project that she’s open to exploring in other counties in the future.
“Our main goal is education,” Butler said about fireflies. “If I’m learning, I’m sharing it with other people that it will continue to grow, not just here but across the state or across the country.”
Brian Whipkey is the outdoors columnist for USA TODAY Network sites in Pennsylvania. Contact him at bwhipkey@usatodayco.com and sign up for our weekly Go Outdoors PA newsletter email on this website’s homepage under your login name. Follow him on Facebook @whipkeyoutdoors.
