Fireflies, the neglected revelation

A blue ghost firefly (Phausis reticulata) leaves a shadow in flight in an Appalachian Mountain forest. © Radim Schreiber

Leviathan Press:

As a child, I remember seeing fireflies flickering and flying from time to time in the early summer evenings near my suburban home. It was fun to catch a few alive and put them in a glass canning jar and watch them flutter in the jar with the lights off. As an adult, I have never seen these luminous creatures in the city again.

Mizuno Toshikata, "Thirty-Six Best Writings: Firefly Hunting", 1891. © ukiyo-e.org

The protagonist of today's article is not only a master at catching fireflies, but he is also constantly discovering new species of fireflies.

On a June night in the muddy swamps of New Jersey, an hour’s drive from his home, Christopher Heckscher was alert for any light. Although this wilderness is located in one of the most densely populated areas in the U.S.

——The Northeast metropolitan area, but he is an explorer. At this moment, when the stars appear from behind the clouds, he is waiting for the stars and fireflies on the ground.

Heckscher, a professor at Delaware State University and an ornithologist who studies thrushes, sparrows and other migratory birds, had long been interested in another fascinating flying insect, however, and he has been publishing papers on fireflies for nearly 20 years.

Ornithologist Heckscher also has a special liking for fireflies. © Karine Aigner

During the COVID-19 pandemic, Heckscher has been able to focus on the insects he loves because they are close to his home region. He worked with the North American members of the Firefly Specialist Group of the International Union for Conservation of Nature (IUCN) Species Survival Commission to determine which firefly species are closest to extinction using the IUCN's extinction risk assessment criteria (the IUCN maintains a global list of threatened species known as the Red List).

The team concluded that 18 firefly species are threatened, but the bottom line is that scientists know very little about the approximately 170 named firefly species in the U.S. and Canada. “We had to label more than half of the species we assessed as ‘data deficient,’ ” said Candace Fallon, a conservation biologist who co-led the analysis. “We’re still in the information-gathering phase, still figuring out what species are in the U.S. and where they are distributed.”

Heckscher is working to fill those data gaps. Colleagues say he's a rare talent. "There aren't many people who can get to the wetlands in New Jersey at the right time and really distinguish between the different species of fireflies," said Sara Lewis, a professor at Tufts University and co-chair of the IUCN Firefly Specialist Group. In the field of firefly conservation, she said, Heckscher's quest is "very exciting."

Each species of firefly flashes at a different rate. © Xerces Society

As the sun set that June evening and the sky turned purple, Heckscher saw small hills of ferns, sedges, and mosses, signs of a healthy wetland. Woodthrushes sang in dueling songs across the marsh, like a chorus of birds. A heron flew by, its huge wings silhouetted against the last rays of daylight.

A friend who studies moths tipped Heckscher off to the existence of this pristine mire, wetlands that rely on rainwater and have accumulated mosses in their acidic waters for centuries, turning them into giant, acidic sponges. As night fell, a nighthawk whistled by—an endangered bird that proved this little slice of nature outside of suburban New Jersey still works the same way it has for thousands of years.

Heckscher looks forward to the fireflies appearing as the sky darkens a few minutes after sunset.

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Twenty-five years ago, Heckscher was a wildlife biologist for Delaware's Natural Heritage and Endangered Species Program, responsible for managing the state's rarest species. One of those projects had him searching for the Bethany Beach firefly, which hadn't been seen since 1968.

© Sierra Club

Are the Bethany Beach fireflies extinct, have they been stymied by the dangers that threaten fireflies worldwide, such as habitat loss, light pollution and climate change, or have they simply been ignored for 30 years?

Scientific descriptions of the species offer few clues, except that it was once found at Bethany Beach, Delaware. Frank Alexander McDermott, a firefly researcher, published the first paper on the species in 1953. James E. Lloyd, a professor at the University of Florida known as "Dr. Firefly," was the last person to see it.

**Fireflies, known as "lightning bugs" in the American South and Midwest, are neither Diptera nor Hemiptera. ** Scientists reserve the term "Hemiptera" for certain species of insects with piercing-sucking mouthparts, a definition that excludes ants, butterflies, and beetles.

Fireflies are beetles, magical though they are, they are still six-legged insects.

As Lynn Faust, a firefly expert in Tennessee, puts it, **adult fireflies use their flashing as a "love song of light." ****A male firefly flashes his own signal, and when a female recognizes him, she flashes back. ****Females of some of the firefly species Heckscher studies can also change their flashes to lure fireflies of other species, which they prey on. **For firefly larvae, flashing can also warn predators, just as the red of a ladybug or the orange of a monarch butterfly does.

Many land creatures can produce light using chemicals, including various fungi, earthworms, millipedes and fungus gnats, Lewis wrote. But beetles are the champions, with about 2,500 different species of beetles that can produce light, most of which are fireflies.

**Their light comes from an organ in their abdomen called a lantern. Inside this organ, oxygen interacts with a small molecule called luciferin. **Some scientists believe that fireflies create the pulsing pattern by regulating the flow of air.

© Tenor

**There are at least 2,200 species of fireflies worldwide. Each has a larval (immature) form that glows. **These larvae feed on snails, slugs and worms and play an important role in the ecological web. But not all firefly species have glowing adults.

**About 60 to 75 percent of firefly species glow as adults, according to Oliver Keller, a biologist with the Florida Department of Agriculture and Consumer Services. **These species are found primarily in Asia and east of the Rocky Mountains in North America. Fireflies thrive in environments with moisture in the air and on the ground, and the western United States is generally too dry for them to survive.

**The rest of the firefly species are "dim-light" fireflies. They glow as larvae and eggs, but not as adults. **Instead, the adults attract each other through scent-like pheromones, which they sense with their fine antennae. These fireflies lack photophores for flashing (there are some intermediate species that have both tiny photophores and complex antennae to detect pheromones). In some other species, the female glowworm emits a faint, constant glow, but doesn't fly. She simply crawls to the top of a blade of grass, or up a tree trunk.

Photuris mysticalampas (mysterious lantern firefly) is found at the Nanticoke Wildlife Area, one of only six locations in Delaware and Maryland. © Karine Aigner

The Bethany Beach firefly Heckscher was looking for both flashes and flies. Although some thought the species was extinct, Heckscher's instinct told him it must be hiding in a neglected wetland. By studying aerial photographs from 50 years ago, Heckscher narrowed his search to areas where fresh water pooled between sand dunes far from the ocean, and grass and shrubs grew thick. Heckscher headed to one of those wetlands and quickly captured the long-lost firefly. Scientists have since found the species in a few smaller wetlands along a 27-mile stretch of the Atlantic coast in Delaware and Maryland.

It was the beginning of a series of amazing discoveries. In 2004, Heckscher spotted a firefly he couldn't identify, rising from moss beside a river that emptied into the Delaware Bay. He thought it was just an oddball until he found an identical firefly near another river in the state's Chesapeake Bay watershed.

Heckscher holds a specimen of the mysterious lantern firefly. The label records where and when he found it. © Karine Aigner

He discovered a new species of firefly. He gave it a scientific name, Photuris mysticalampas (informally known as "mysterious firefly" or "mysterious lantern firefly").

Heckscher has been searching for the elusive fireflies ever since, and has found them to be truly awe-inspiring. One hot, humid evening, he was searching for the mysterious lanternflies in a cedar swamp. Distant flashes of lightning lit up a pink haze of swamp. Trees and ferns suddenly emerged from the darkness, aglow in pink light, dotted with the yellow-green flashes of the fireflies.

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Heckscher’s greatest achievement is his method for finding fireflies: finding pristine and unusual wetlands. It was this strategy that led him to a peat bog on the Edward G. Bevan Fishery and Wildlife Management Area in southern New Jersey in late June.

**The fireflies Heckscher studies belong to the genus Photuris, which are particularly difficult to identify. **Many other types of fireflies can be identified by their external features, but these species are not included because many of them look very similar. To identify these fireflies, he said he has to pay close attention to their flashing patterns (for example, the mystery lantern firefly usually emits a continuous signal that lasts between 0.4 and 0.8 seconds and repeats every 3 to 7 seconds).

Heckscher, the "firefly hunter". © Karine Aigner

Around the edge of the swamp, fireflies signaled to each other. Some would flash in a steady rhythm and then pause, while others would flash erratically as they flew, but all were beyond Heckscher's reach. To follow a firefly while running quickly through the dark swamp meant stumbling over the tall, twisted vegetation.

Finally, one flew within reach. Heckscher expertly switched on his headlamp to track it as it flickered. A Photuris anna was flickering in the net, and he dropped it into a collection bottle.

**Anna's firefly is a species Heckscher had introduced to science just a few months earlier. Named after one of his daughters, it is commonly known as Anna's firefly, which frequents a similar swamp in New Jersey. **The best specimens of this species are now preserved in the entomology collection of the Smithsonian's National Museum of Natural History so that they can be referenced by other scientists.

Each specimen Heckscher collects provides him with more data. He flips to the last page of his field notebook and writes down key information in tiny handwriting, including the date, temperature, and the firefly's flashing pattern. He tears off a piece of paper smaller than a postage stamp. "Slow flash," he describes briefly. "Freshwater peat bog," he then notes the habitat and places the paper into a vial of fireflies.

European firefly (Lampyris Noctiluca). Nighttime light pollution from anthropogenic sources is increasing worldwide and is considered a major threat to nocturnal biodiversity. © Pinterest

Soon Heckscher caught his second firefly, also an Anna firefly. A predawn trip to study birds was approaching, but the swamp held too much promise for him to leave without catching another firefly.

**He was hoping to discover an entirely new species in this isolated wetland. A few weeks earlier, across a sandy passage, he had caught a firefly that seemed to flash differently than any he had seen before. **It was too early to say it was a new species, and on this cool June night, he had given up hope of seeing anything like it again.

However, he did not despair. He moved his firefly collection to his home because of a leaky roof at his university office. He had collected all the specimens of what he believed to be another new species. This firefly only flashes once, while other similar-looking fireflies flash four times. However, he would not announce the discovery to the scientific community until he compared it with other species in the Smithsonian Institution's firefly collection.

Firefly specimens collected by Heckscher, with instructions indicating flashing frequency, body shape and other relevant information. © Karine Aigner

Heckscher had other goals for the evening. In a nearby swamp, he caught a Photuris eliza, another new species he had just named. It was also named after one of his daughters. He found it in Delaware and had never seen it outside that state before. He wanted to get more specimens from New Jersey to see if its range extended there. All night long, he saw irregular, bright, clear flashes of Eliza's fireflies all around him, but always out of range.

As Heckscher stood in the dark marshland, there was a clatter of traffic on a nearby road. Passenger planes flashed their beacons in the sky. The paved world was closing in on him. As the night cooled, there were fewer fireflies to be seen (their flashing slowed as the temperature dropped), and none came close to Heckscher. Reluctantly, he picked up his backpack and followed the path he had marked earlier with tape, through the dense brush, toward a sandy path.

© Science Friday

Suddenly, he turned off his headlamp. A firefly flickered near his elbow. For just a few seconds, it was placed in a collection bottle. When he found the firefly, it was injured, so it was hard to tell exactly what it was, but Heckscher suspected it was Eliza firefly. Later, he would compare it to his collection of 1,000 firefly specimens.

The bare white sand on the road gleamed in the light of his headlamp. Heckscher turned off his headlamp again and snatched a glowing firefly from the bushes and placed it in another collection bottle. It represented the third of four firefly species that Heckscher had recently discovered and described scientifically.

**He named the species Photuris sheckscheri in honor of his father, Stevens Heckscher, a mathematician and naturalist.**The fourth firefly species Heckscher recently described was named Photuris sellicki after Canadian explorer Philip Sellick, who found it in New York State's Adirondack Mountains, a far cry from these coastal marshes and a different environment, so he wouldn't have encountered it here. He first noticed the species in 2008. A lot has changed since then.

Heckscher said he has noticed a surge in public interest in fireflies in the past five to ten years, a phenomenon he attributes to Foster’s book, “Fireflies, Glow-worms and Lightning Bugs.” Although she wrote the guide for the public, it was peer-reviewed by other firefly experts, just like published scientific research.

“There are firefly tours and festivals now, and fireflies are becoming popular,” Heckscher said.

© Xerces Society

Scientists and conservationists welcome the public's involvement. "Everyone has a role to play," Furlan said. "Whether it's protecting habitat, assisting with research through community science programs, students choosing to study fireflies, or getting people excited about identification, there are so many different ways to make a difference."

**The dependence of some fireflies on rare habitats has not changed since Heckscher began his quest. **In 2019, the Xerces Society and the Center for Biological Diversity, another wildlife conservation group, filed a petition with the US Fish and Wildlife Service asking that the Bethany Beach firefly, the species Heckscher rediscovered in 1998, be placed on the federal Endangered Species Act emergency list. **Fron expects a conclusion in 2024.

The firefly of the genus Acropora is the most common species in North America. It is about half an inch long and briefly flashes a yellow-green light when it flies. © Karine Aigner

The petition states that homes are being built on a wetland that has a large population of Bethany Beach fireflies. This species is only found in Delaware and Maryland, and Delaware has listed it as endangered. It is the first firefly species to be considered for federal endangered listing. In March 2023, the Zex Society also filed a petition to list the Mysterious Lantern Firefly as an endangered species.

“If you value biodiversity on Earth,” Lewis said, “ it’s not just about lions or tigers or bears. Fireflies are amazing beetles, of course, but they are also a vehicle for raising awareness about the importance of conserving biodiversity, especially insects .”

That’s why Heckscher stays in the swamp at night. “If I had caught more than two firefly species from the New Jersey swamp, I would have been very happy,” he says. “I was surprised that this single swamp had three undescribed firefly species before I published my paper.”

With new data from these specimens, the firefly explorer has added a few glowing dots to the biodiversity map, helping shape future plans for these brilliant beetles. “When you combine a rare insect with a rare habitat type, it makes for an important conservation goal,” Heckscher said. “I haven’t been getting much sleep lately, but I don’t want to give up. I can’t. I love the challenge.”

By Madeline Bodin

Translated by tim

Proofreading/Yuba and Lean Bamboo

Original article/www.smithsonianmag.com/science-nature/illuminating-science-behind-fireflies-180982112/

This article is based on the Creative Commons License (BY-NC) and is published by tim on Leviathan

The article only reflects the author's views and does not necessarily represent the position of Leviathan