For this series, Edgar Berg captured several ecosystems that are home to fireflies on the island of Palawan in the Philippines, including the Nagsagipi River, a red mangrove forest, the Iwahig River, and Cleopatra’s Needle.

Words by Oliver Milman
Photographs by Edgar Berg

Fireflies are disappearing in many parts of the world, writes Oliver Milman, author of The Insect Crisis. What does it mean to lose some of the Earth’s most magical beings?

Over the past two decades, Christopher Heckscher has discovered some of the most pyrotechnic species on the planet hiding in plain sight in the most densely populated region of the United States.

Armed with a butterfly net, sturdy boots, and a headlamp, Heckscher, an ornithologist by trade, has found and described seven different firefly species in the bogs, marshes, and dunes of Delaware, New Jersey, and New York. Some live within just a few hundred yards of people’s houses. One, Photuris eliza, is named after one of Heckscher’s daughters; another, Photuris sheckscheri, after his father Stevens, a mathematician and naturalist.

Heckscher’s enthusiasm for traipsing around wetlands after dark, hoping to swipe a flying insect and plunge it into a vial of alcohol, might be unusual. But his discoveries occurring so close to densely populated areas suggests that much of people’s casual disconnect from nature extends even to fireflies, those nocturnal icons of summertime, revered in verse throughout the ages and equipped with a light show that can bring new observers to tears.

“It’s still pretty shocking to find new species in such a developed place,” said Heckscher. Discovering a new insect species isn’t itself unusual: We don’t even know with confidence how many there are in the world to the closest million; estimates range from five million to 10 million species. But it is perhaps surprising that more isn’t known about a beloved creature that flashes light at us in the vicinity of our major cities.

“We still don’t know basic information about where they occur [or] how many species there are,” said Heckscher, who added that people are often stunned to learn there is more than one firefly species. “It’s mind boggling to me. How many billions of dollars are we spending looking for life on Mars when we don’t even know about fireflies in North America? There’s this big disconnect, which is unfortunate because we are losing stuff we don’t even know about.”

Fireflies aren’t flies. Nor, if you call them lightning bugs, are they bugs in the strictest entomological vernacular (neither are they a worm, as their flightless glowworm relatives, found in Europe and Asia, would suggest). They are, in fact, beetles—and more than 2,000 species can be found across the globe, on every continent except Antarctica.

Somewhat like a Hollywood starlet who dazzles at a movie premiere after a day spent eating Doritos at home in their sweatpants, most fireflies are drably colored and hard-to-spot when the sun is up, only performing their spectacular show at night. This performance only takes place in summer, making these creatures a dazzling yet ephemeral presence in our world.

Paradoxes swirl around fireflies like few other creatures, yet it is partly because of this mystery that an animal the length of a fingernail can appear to possess magic. “You’d have to be a cold person to hate fireflies,” said Heckscher. “I mean, they can create light from their own bodies. If we were to discover such a thing on another planet people would freak out, and yet it is happening in our backyards.”

Some of the scientific fogginess around fireflies has started to lift recently. A 2021 assessment of 132 species in the U.S. and Canada found that, while data on half this cohort was lacking, at least 18 species are threatened with extinction. “The last five years have been an exciting as well as a scary time for fireflies,” said Sara Lewis, an expert at Tufts University who cochairs the firefly group for the International Union for the Conservation of Nature. “It’s exciting that we’re now examining fireflies and have discovered a lot of new species. The scary part is there are quite a few firefly species being pushed to the edge of extinction.”

We are losing nature’s magicians before we properly know them. 

The plight of fireflies is something most people don’t dwell upon, much like we don’t tend to ponder the life conditions of food delivery drivers or stage performers once they’ve passed from our view. But it’s something that many, when prompted to consider, relate to as a magical childhood experience that is now out of reach. What these people are describing is a mourning over environmental loss, called “solastalgia.” 

“When I sit next to someone on an airplane, and they find out what I do, they ask me why there aren’t as many fireflies as there used to be,” said Lewis. “Everyone asks me this, all the time. People have noticed this everywhere.”

Now, the retreat of fireflies from our lives is set to be etched into the annals of the federal government. In September, the U.S. Fish and Wildlife Service announced it will add the Bethany Beach firefly to the endangered species list, the first ever such designation for a firefly. Photuris bethaniensis, first discovered in the eponymous Delaware town in 1949, is being squeezed out of the thin coastal strip that makes up its range in Delaware, Maryland, and Virginia by an amalgam of threats that now haunt many fireflies: habitat razed for housing, wafts of toxic pesticides, and what Lewis called the “many-headed monster” of climate change, which is slowly drowning the firefly’s home via sea level rise.

Less than half an inch long with a brown body and a mushroom-shaped black marking on its head, the Bethany Beach firefly is a victim both of its fussiness and our own desire to cluster beside beaches. It is only found in specific habitats known as interdunal swales: grassy, marshy dips filled with ponds of freshwater beside sand dunes. Hemmed in by a highway and sprawling beach homes on one side and the inexorably rising Atlantic on the other, this firefly is being gradually throttled to death.

Heckscher has a fondness for the Bethany Beach firefly, calling it his “gateway” into fireflies after an early career spent studying songbirds. In the 1990s, Heckscher took on a project to find the species, which had not been seen for 25 years. “I didn’t know where the heck to look other than near Bethany Beach, so I was going to golf courses and front yards. I had no idea,” he said. “But then I thought, ‘The reason it’s rare is that it’s probably in this rare wetland near the dunes.’ My first night there, I found it.”

Catching a firefly like this takes some skill. Jason Davis, a biologist with the state of Delaware, has deduced that the Bethany Beach firefly flies around four to six feet above the perimeter of the swale, roughly in a circle. But even with the flashes, it takes an educated guess as to when to swing the net. “Sometimes you think they’re going this way, and then suddenly they zag,” said Davis, whose survey work helped confirm the firefly is found in similar habitat in Maryland and Virginia, in addition to Delaware. “You see it flash in the dark, and then you’re anticipating where it’s going, so you have to get lucky.”

Identifying a firefly is primarily done through recognition of flash patterns. To pick out the right species of mate from other types of firefly, a male will emit a certain light sequence, to which a female will then respond. This display, which Victorian writers likened to the dance of fairies, can come in long pulses or rat-a-tat blinks. The sequence most often seen in backyards at dusk across the eastern U.S. is that of Photinus pyralis, or the big dipper firefly, a hardy generalist that flies in a J-shaped trajectory, lighting on the upswing.

The Bethany Beach firefly, by contrast, emits a double green flash. It cannot survive human encroachment, requiring the shelter and moisture of undisturbed swales to mate and lay eggs that, remarkably, hatch larvae that can live for up to two years under the sodden soil, hunting slugs and worms. When they finally become flying adults, they only live for a few weeks, flashing away for a mate so the cycle can repeat again. Some females will try to lure other firefly species and then eat them in order to obtain protective toxins called lucibufagins, which they can pass onto their offspring.

Our species’s habits risk wiping out these tiny, spellbinding societies, just one front in our broader assault on insect life that is decimating bees, butterflies, and other six-legged life. We build houses and golf courses on dunes and wetlands, we spray toxic chemicals, we trample fragile vegetation underfoot without a second thought, we introduce invasive new plants, and we combust vast quantities of fossil fuels to power our homes, cars and factories, thereby redrawing coastlines. 

“With all of these things combined, it’s going to be a struggle for this species,” Heckscher said of his Bethany Beach rediscovery. “If we don’t protect these wetlands, we’ll lose them.”

Our most undignified of insults, however, is to strip away the spell of fireflies’ nighttime twinkling. Until the industrial age of humanity, the only light to bathe the Earth typically came from the sun, other stars, the moon, the fires built by humankind, and bioluminescent creatures like fireflies themselves. Now, we have flooded the world with ever-present artificial light. Inky darkness means a dance of love, but the glow of modern life “is a recipe for heartbreak,” as Lewis put it. Males stop signaling, females have nothing to respond to, and the romance fizzles. 

On the barrier islands of Delaware, much of the remaining Bethany Beach firefly habitat is on ostensibly protected state land, but light pollution respects no boundaries, seeping across the highway and into the swales. Here, and around the world, we are tearing apart the canvas upon which fireflies work. As Henry David Thoreau pointed out more than 170 years ago, “what were the firefly’s light, if it were not for darkness?”

Thoreau was enchanted by the sparkle of fireflies, comparing them, in his Journal, to the heavens: “Do not the stars, too, show their light for love, like the fireflies?” The comparison endures to this day, with scientists naming a far-flung galaxy the Firefly Sparkle due to its network of huge star clusters that resemble a swarm of fireflies.

It’s easy to see why past generations thought of fireflies as magic. We have only recently begun to understand the process by which fireflies are able to use bioluminescence—luciferin, luciferase, and oxygen interacting in the “lantern” of their abdomen. Bioluminescence is most commonly a feature of the marine world, deployed by shrimp, jellyfish, and plankton, but many of us will only witness it in fireflies.

At first, the light is a defensive warning of toxicity, with even firefly eggs glowing. Then, as adults, the light acts as a matchmaker.

Long before we understood these mechanics, we freighted fireflies with meaning: The Navajo people saw fireflies as spiritual messengers; in Japan, they were a metaphor for passionate love, as described by the eighth century poetry anthology Man’yōshū; in Italy a firefly in the house is a sign of good luck. They were plucked from the air for jewelry, to adorn the hair, or, as a rite of passage for kids in rural America, trapped in a mason jar. Most often, they simply provoked awe. “How they shone!” John Ruskin, the British polymath, wrote during a trip to the hills above Siena, Italy in 1870. “Moving like fine-broken starlight through the purple leaves. How they shone!”

Fireflies can still move the gears of the heart, of course, just less frequently than before. Increasingly, they are a thing of wildlife tourism, like lions and rhinos, rather than an everyday occurrence: A popular ticketed experience in the Great Smoky Mountains National Park is to view synchronous fireflies, where the males and females flash at each other in unison. Seeing such phenomena is a draw—it’s estimated more than one million tourists travel each year to sites across a dozen countries to see fireflies—but itself poses a threat to the creatures from the crushing presence of humanity.

As neighbors, they can be less well known. While the western U.S. is not as known for fireflies, they do exist there in pockets, to the surprise of even long-term residents. “I’ve spoken to people who have managed land for 30 years and not known fireflies were there,” said Candace Fallon, a conservation biologist at the Xerces Society. “People can be grossed out by insects, but fireflies almost feel like cheating, because everyone loves them. We have people who come out to spots near their homes and start jumping up and down and tearing up because there are fireflies there.”

Turning this affection into conservation action isn’t straightforward. Ben Pfeiffer, a Texas-based entomologist, holds talks on fireflies across the U.S. He hears countless maudlin tales of fireflies’ disappearance from people who then go home and carry on as before. “The lawnmower is a big threat to fireflies. People mow the riparian area where fireflies like to live so it looks like a park. My goodness, it upsets me,” Pfeiffer said. “There’s a cognitive dissonance where we hear something is destructive, and then we just go, ‘Uh huh’ and do what we want, because we think the land is just there to serve us.”

But Pfeiffer also sees reason for optimism in groups striving to aid fireflies, leveraging that nostalgia from when they were more abundant. We may be acting too slowly on climate change, habitat loss, and curbing pesticides, but we are moving. Perhaps one day, we will learn to not put our lights on full blast all night, too.

If we don’t, we risk missing wonders. A few years ago, Pfeiffer was sitting in his pick-up truck on a warm May evening at an undeveloped stretch of the Guadalupe River in Comal County, central Texas, counting fireflies. Suddenly, there was an amber-colored flash, bright enough to illuminate the grass, as a soaring bright light streaked across the field.

“It was like a supernova had gone off. All the other fireflies stopped flashing for about five seconds because it was so bright,” Pfeiffer said. “It was the coolest thing.” He rushed to capture the firefly responsible with a net, unsuccessfully, but his notes on the incident convinced him that he’d seen Pyractomena vexillaria, not witnessed in the region since the 1940s. Pfeiffer bestowed it with the common name ‘the amber comet.’

“Whether we can still develop land while protecting things like the amber comet or the Bethany Beach firefly is the million dollar question,” he said. “We aren’t going to lose fireflies entirely, but we are going to lose the spectacle of five or six species flashing at you at once, which blows you away. We are getting less of a symphony and more of a one-chord song.”

This story first appeared in Atmos Volume 11: Micro/Macro with the title, “Flashing Lights.”

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Our universe is an endless series of worlds within worlds, from the molecular ones we carry to the vastness of the cosmos. Everything comes down to scale. Atmos Volume 11: Micro/Macro looks at patterns, systems, and size, exploring the interconnectedness of life on our planet,

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