If You Build It, They Will Glow

Fireflies are disappearing in Louisiana; LSU AgCenter scientists hope to bring them back

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Knowing Nature

When the Louisiana sunset fades into that signature purple-blue dusk, a short window of time cracks open, and the lightning bugs fly through it. Anyone who has loved a patch of woods can vouch for the extra layer of magic lent by the firefly, who by light in its abdomen, puts on a show to attract its mates—and by accident, us. 

To see them light up as the sun goes down on a long summer’s day feels like being let in on a secret. Or, at least, it did.

At some point over the last twenty years, we looked up from our busy lives and realized the fireflies had disappeared from the places we remember. At this rate, today’s children are likely to grow into adults who think fireflies are the stuff of fairy tales, mere forest sprites. 

What if we had to tell them it was our fault the fireflies went away? That the HOA would have charged us a fine if we didn’t bag our leaf litter in plastic, and we didn’t know how bad that was for the fireflies until we had done away with all their progeny in a single spring day of yardwork? 

Former Jean Lafitte mayor (now councilman) Tim Kerner Jr. wanted to change that story, to be able to say that we noticed the fireflies’ absence, learned more about their needs, and took action to save them for future generations. 

In late 2024, Kerner emailed the LSU AgCenter to ask if they could do something to strategically restore the habitat of the Wetland Trace, where he no longer witnessed the magical critters he remembered from his youth. Though the LSU AgCenter didn’t have any firefly experts on staff, it did have an urban entomologist, with a soft spot for fireflies. 

“Fireflies Are Cool”

Dr. Aaron Ashbrook, originally from Michigan, did his doctoral work on a different bug forever nestled into human lore: bedbugs. Urban or structural entomology typically deals with insects in and around the home, Ashbrook explained, so a lot of pest insects end up under his microscope—hence the bedbugs. But urban entomology is a big bug umbrella, and there’s room for curious or beneficial insects to be studied, too. 

Ashbrook, along with LSU AgCenter Extension Associate Christine Gambino, whose studies focus on entomology, had worked on a few projects involving pollinators, such as bat and butterfly conservation, and had tackled the question of how to support pollinators while safely managing mosquitoes. That’s how the project of the fireflies (who are valuable pollinators) landed in their laps. 

Ashbrook was happy to accept it—he’s a big fan of lightning bugs. As evidence, he can point to a shelf in his office, where sits a hat that reads, “Fireflies Are Cool.” He grew up admiring the fireflies in the yard of his childhood home in Michigan, where his parents still live. The fireflies have disappeared there, too. 

“They really do rely on being able to detect light from each other. If they can’t see light because of excess human light, and they don’t successfully mate—that can basically crash a population in just one generation.” —Dr. Aaron Ashbrook

As it turns out, these bioluminescent beetles are disappearing in a lot of places for a lot of reasons, including habitat loss and urban development, leaf litter removal, invasive insects like fire ants, light pollution, and insecticides. But some factors might matter more than others. Ashbrook suggested that comparing the firefly situation on his family’s property in Michigan to the challenges in Jean Lafitte was helpful.

“We don't have invasive ants there, and there are no mosquito control districts where I grew up,” he said. “Those are two of the things that really get implicated for firefly decline.” And still, the flickering lights had gone dim anyway. 

The biggest change his family property has undergone since he was a child, he went on to say, was the loss of a large, open prairie field next door; it’s now someone’s house and yard. And, unlike when he was growing up, his parents now leave exterior lights on at night. For these reasons, Ashbrook hypothesizes that habitat loss and light pollution are the primary forces decimating the fireflies, in both places.

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The Firefly Crew

The first step in bringing the fireflies back to the Wetland Trace area was to survey it for evidence of any remaining firefly presence, a process Ashbrook and Gambino conducted in collaboration with the Louisiana State Arthropod Museum. Sadly, they didn’t find anything in multiple visits to the area, but the result wasn’t entirely unexpected. 

Rebuilding a firefly habitat requires knowing exactly what the creatures need, so the team began studying to fill in their firefly knowledge gaps, collecting information about life cycles, food, and the specifics of their habitats. They found and connected with several online communities that source firefly sightings from the public, such as the Xerces Society for Invertebrate Conservation, Firefly Atlas, and the Glow Patrol in Texas. Along the way, Ashbrook and Gambino applied for and received a grant to hire a student worker, an enthusiastic LSU undergraduate named Briana Carpenter, to assist with the workload.

Soon enough, a mayor’s plea had turned into a group project at the LSU AgCenter, populated by scientists and aided by park staff and volunteers. All of them think fireflies are cool.

Why They Glow

Some magic loses its sparkle once you learn how it works. The opposite is true with fireflies: the closer you look at their habits and life cycles, the more extraordinary they become. The quality we know them for best—their blinking light show at dusk—is no casual evening hobby. It’s their courtship ritual, and it’s one of the last things they do before departing this earth. 

Fireflies are peculiar little beetles—yes, they are beetles—and their specificities vary a bit across more than two thousand species worldwide. Some species don’t glow visibly to humans at all, but they’re still in the Lampyridae family and are classified as fireflies. Generally, adult females will hang out on single, sturdy blades of grass around dusk, waiting for a male to fly around and blink just so—in the way that tells her he’s a member of her same species.  

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“The males will flash at different times so they can attract the female of their species and not intermingle,” Gambino explained. “If, say, a Photorus and a Pyrodroma flash at each other, they're going to be like, ‘You're not for me. Get out of here. You're not of my species.’”

Once she’s found a suitable blinking male, the female then blinks the same pattern back to him: a signal to take her out on the town, so to speak. After their date, she’ll lay her eggs in the coziest, safest spot she can find, which is ideally a pile of leaf litter. A pile of dead leaves looks like yardwork to most people, but leaving your leaves where they fall can make an enormous difference for a mother firefly. If unbothered, the eggs hatch into larvae—some species’ larvae are colloquially called “glowworms”—who might spend years hunting down unsuspecting snails and slugs. They inject their prey with neurotoxic digestive enzymes, which paralyzes and turns them into a digestible goo. 

“They are voracious predators,” Gambino explained. “The larvae can live two to three years depending on how much food they consume, because not all of the adults feed. Some just, you know, pupate, then it’s time to mate.”

The firefly project at Jean Lafitte operated on the idea that if the scientists built and protected a consummate firefly habitat at Wetland Trace—native grasses so sturdy and leaf litter so rich, a female firefly would blink in delight when she saw them—that the fireflies would simply come back.

We don’t have to create a wild story to explain why fireflies glow, and we don’t need magic to save them. We only need to accept that, however whimsical they may be, fireflies are real and fragile living things that are affected by our actions.

To this end, in mid-2025, the crew organized dozens of volunteers around Jean Lafitte to bring their own leaf litter to deposit at designated sites, resulting in about two hundred new feet of ideal firefly egg-laying area. The team then consulted with the Louisiana Department of Agriculture and Forestry to carefully choose native plants that would thrive at the site. They worked with Sweet Fern Landscapes to special-order a huge assortment of native plants, such as swamp milkweed, sugarcane grass, lizard’s tail, button bush, and little bluestem. The scientists and about thirty volunteers then planted all 350 plants at Wetland Trace last November, surrounding old growth native trees that already existed in the park.

Now, all they have to do is keep the plants alive, leave the leaf litter, and wait. The team has been monitoring the area for signs of firefly life since February and will continue through September.

“This could, in theory, take years to happen,” Gambino admits, “so it's kind of like pushing a boulder up a hill. We won’t know until we know.”

Lights Off For Lampyridae

We don’t have to create a wild story to explain why fireflies glow, and we don’t need magic to save them. We only need to accept that, however whimsical they may be, fireflies are real and fragile living things that are affected by our actions. They have, like so many others in the natural world, lost their signals among our own—and some of the most effective things we can do to encourage their return to our own little corners of the world are also some of the simplest: leave your leaves where they fall, and turn off your lights at night.

“They really do rely on being able to detect light from each other,” Ashbrook explained. “If they can’t see light because of excess human light, and they don’t successfully mate—that can basically crash a population in just one generation.”

How many times has your innocent porch light interrupted a firefly soul connection? Who’s to know, but if you’re leaving your lights on to deter criminals, Ashbrook thinks you should reconsider.

“The idea with lights at night as a security measure … they only provide light to criminals,” he said. “A criminal cannot see at night without assistance. But you can see a criminal walking around with a flashlight.”

While they wait patiently for signs of life at Wetland Trace, the firefly crew at LSU AgCenter isn’t sitting on its thumbs. Gambino has reported new firefly sightings across Baton Rouge and St. Francisville, and she has been inching toward a personal goal of adapting these habitat restoration methods for use everywhere. Specifically, she’s doing preliminary habitat work a little closer to home at the Burden Museum & Gardens in Baton Rouge.

“If you go on the Firefly Atlas website, there is a whole list of places that are now designated firefly conservation areas, and I'm going to try to make Burden into one of those,” Gambino waxed. “Like, that's my big goal.”

Speaking of Firefly Atlas, everyone on the firefly restoration team emphasized how important citizen scientists are to the project. If you see fireflies, further the cause by submitting your sighting to one of the public databases online. fireflyatlas.org or inaturalist.org are great places to start.