Fireflies (beetles in the family Lampyridae) include about 2,200 species worldwide, with breathtaking luminous displays that make them one of our most charismatic mini-fauna. So no surprise that their popularity has been skyrocketing lately in countries like India, Mexico, Taiwan, Malaysia, and the United States. In a 2021 review, we estimated that about a million tourists visit firefly-watching sites spread across 12+ countries during a typical year!
I’m absolutely thrilled that so many people are stepping into the night to experience the sheer wonder of these dazzling creatures! And tourism can certainly be a boon, creating jobs and providing revenue for local communities.
Yet there’s a dark side to fireflies’ popularity. Confronted with rapidly growing visitor numbers, the stars of the show are often subjected to trampling, disturbance of larval and adult habitat, and light pollution.
Promoting sustainable firefly tourism in the U.S.
More than 150 different firefly species are sprinkled across the United States, including several whose mating displays have grown into seasonal tourist attractions. These include the synchronously flashing Photinus carolinus and Photuris frontalis fireflies, along with many others that put on remarkable light shows.
In April 2021, The Xerces Society hosted the first-ever U.S. firefly tourism charette, a virtual meeting of park managers, tour guides, event planners, and firefly experts. We discussed the many challenges of managing thousands of visitors while still protecting local firefly populations, and came up with guidelines for site managers and tourists.
Aimed at moving U.S. firefly tourism toward greater sustainability, these guidelines are now available on the Xerces website, including:
Yup. This happened because I recently had a chat about all things firefly with Alie Ward for her amazing Ologies podcast! Learn how these tiny insects illuminate the night, some dos and don’ts of watching fireflies, choosy females, nuptial gifts, California pink glowworms, light pollution threats, little-known fireflies of the Western USA, and how you can help the world stay aglow with these beloved bugs.
Living light is everywhere. It turns out that bioluminescence – the emission of light by living organisms – was invented about 40 separate times during the evolution of life on Earth. Today, the sea houses the vast majority of light-producing creatures ; these include bacteria, dinoflagellates, crustaceans, jellyfish, starfish, octopus, and many denizens of the deep sea. One night while kayaking the Sea of Cortez, we swam among luminous dinoflagellates so that our bodies, and the dolphins swimming nearby, were outlined in a fiery glow – a truly memorable experience!
Bioluminescence is much less common on land, although this light-producing talent shows up in fungi, a snail, several earthworms, and a host of insects – fungus gnats, millipedes, click beetles, railroad worms and, of course – in fireflies! I recently discovered some tales of cross-species exchange between fireflies and glowing sea creatures. Tucked into the memoirs of two great 20th century naturalists who lived on opposite sides of the world are descriptions of a fascinating phenomenon where fireflies got distracted by sea creatures glowing in the surf.
The first luminous tale comes from the pioneering ecologist and gifted writer Rachel Carson (1907–1964), who gave us Silent Spring and taught us how to cultivate wonder (see earlier post). Trained as a marine biologist, Carson loved the ocean and spent summers along the rocky coast of Maine. In August 1956, she wrote a letter* to her dear friend Dorothy Freeman about walking down to the shore one dark and windy night:
“To get the full wildness, we turned off our flashlights – and then the real excitement began… the surf was full of diamonds and emeralds, and was throwing them on the wet sand by the dozen…”
And then, along the shore…
“A firefly was going by, his lamp blinking. We thought nothing special of it, but in a few minutes… There’s that firefly again… he was flying so low over the water that his light cast a long surface reflection, like a little headlight… He “thought” the flashes in the water were other fireflies, signaling to him in the age-old manner of fireflies! Sure enough, he was soon in trouble and we saw his light flashing urgently as he was rolled around in the wet sand…You can guess the rest: I waded in and rescued him.”
A similar episode from the other side of the world appears in My Family and Other Animals, a memoir by the British naturalist Gerald Durrell (1925 –1995). Perhaps you’ve seen the fabulous PBS series The Durrells in Corfu? Then you’ll know that as a young boy, Durrell and his family lived on the Greek island of Corfu.
There he recalled a glorious night romp among living lights with his family:
“The phosphorescence was particularly good that night. By plunging your hand into the water and dragging it along you could draw a wide golden-green ribbon of cold fire across the sea, and when you dived as you hit the surface it seemed as though you had plunged into a frosty furnace of glinting light. When we were tired we waded out of the sea, the water running off our bodies so that we seemed to be on fire, and lay on the sand to eat.”
Then the fireflies appeared:
” Never had we seen so many fireflies congregated in one spot; they flicked through the trees in swarms, they crawled on the grass, the bushes and the olive trunks, they drifted in swarms over our heads and landed on the rugs like green embers. Glittering streams of them flew out over the bay, swirling over the water, and then, right on cue, the porpoises appeared, swimming in line into the bay, rocking rhythmically through the water, their backs as if painted with phosphorus… With the fireflies above and the illuminated porpoises below it was a fantastic sight. We could even see the luminous trails beneath the surface where the porpoises swam in fiery patterns across the sandy bottom, and when they leaped high in the air the drops of emerald glowing water flicked from them, and you could not tell if it was phosphorescence or fireflies you were looking at.”
For a deep dive into bioluminescence in the sea – and how it’s been harnessed by humans – you might enjoy this fantastic article by Ferris Jabr. And next time you find yourself at the edge of the sea, keep your eyes open and maybe you’ll be rewarded with a glowing tango of sea creatures and fireflies!
*I’m so grateful to Martha Freeman author of Always, Rachel, for telling me about the firefly letter, which was written in August 1956 to her grandparents, Dorothy and Stan Freeman. And thanks also to Hess Muse for alerting me to Gerald Durrell’s night romp with the Corfu fireflies.
Around Christmas each year, I start getting reports from astonished fans about what looks like glowing fireflies lighting up nearby trees. Just last week my neighbor in New Hampshire was thrilled to see what he thought was definitely the courtship display of blue ghost fireflies!
If you’ve followed my posts, you know that fireflies across most of the U.S. survive winter hanging out in a juvenile stage. But… these glow-worms stay underground and are typically dormant until temperatures warm up in the spring. You might also know there’s a real Winter Firefly (Ellychnia corrusca) whose adults spend winters hunkered down on tree trunks. But… these are dark fireflies whose non-luminescent adults only begin flying in the spring.
It’s mid-winter, and lightningbug mating season is still months away, so what the heck is going on??!! Wishful thinking? Mass hallucination? Nope – it’s a simple case of mistaken identity.
Outdoor laser projectors have recently become a popular addition to winter holiday decor. These projectors send out dancing points of light – when they shine up into nearby trees, it seems like the treetops are filled with flashing fireflies! Check out the video below:
So next time you start hearing rumors about winter lightningbugs, you won’t get duped – just ask your neighbors! And enjoy the Christmas “fireflies”.
Watching a whole forestful of fireflies flashing together in unison is a truly mesmerizing experience. As I described in an earlier post, males of only a few firefly species are capable of this remarkable feat. Although we still don’t know why this behavior occurs, some researchers at the University of Colorado – Boulder recently developed cool tools to shed new light on how fireflies accomplish this collective behavior.
Using Go-Pro cameras to film Photinus carolinus in the Great Smoky Mountains National Park, Raphael Sarfati and Orit Peleg were later able to reconstruct the 3D flight paths of individual male fireflies. You can read about their study in this month’s Smithsonian Magazine, or check out their original paper in the Journal of the Royal Society Interface.
Their findings provide clues into how insects with relatively small brains can perform such seemingly complex synchronous behaviors. By demonstrating how fireflies kick off their synchrony, this research will inspire new advances in swarm robotics. In the future, their tracking methods could also be adapted for community science projects like Firefly Watch in the U.S. to help scientists monitor long-term trends in firefly populations.
I’m doubly appreciative of fireflies this year, as they’ve given us two fabulous gifts. One, the incredible gift of wonder. The other gift is a tiny molecule, precious and pragmatic.
Luciferase is a light-producing enzyme that was invented by fireflies. Over eons of evolution, it’s been fine-tuned to help fireflies find mates and avoid predators. And now this firefly enzyme has been harnessed by humans to help us fight against the global pandemic of COVID-19.
Surely it seems like magic, but firefly light comes from a carefully orchestrated chemical reaction that happens inside the firefly’s lantern. Luciferase hosts the party, inviting multiple guests (including ATP, oxygen, magnesium, and a much smaller molecule called luciferin), then sparking them to engage in a scintillating conversation that gets them excited enough to give off light.
Ever since its discovery in the late 1940s, firefly luciferase has been harnessed by scientists to improve human health. Early on it got used in food safety testing to detect good food gone bad – that is, food that’s been contaminated by microbes and so is unsafe for human consumption. To test meat, diary and soft drinks, kits made from firefly-derived chemicals would light up to show if a sample was contaminated with even tiny amounts of harmful bacteria. Similar kits were used by the pharmaceutical industry to measure cell viability when they tested anti-tumor drugs. Surprisingly, for over 30 years every smidgeon of luciferase that went into these kits came from wild fireflies harvested by collectors all across the U.S.
Each summer the Sigma Chemical Company recruited a small army of collectors that got paid ~50 cents per 100 fireflies; a $20 bonus awaited anyone who sent in 200,000 fireflies. All told, Sigma extracted luciferase from about 90 million wild-caught fireflies!! (Yes, I know it’s hard to believe. But you can find out more about bounty-hunting fireflies in Silent Sparks Chapter 8: Lights Out for Fireflies? or this story in Atlas Obscura). Quite fortunately for U.S. fireflies and their fans, in the 1990’s scientists finally decoded the DNA sequence that fireflies use to make luciferase. Using harmless bacteria as a bioproduction platform, synthetic luciferase soon became widely available.
Fireflies have enabled many advances in public health and medicine. Once the luciferase gene (this gene’s nickname is luc) was deciphered, the scientific and biomedical uses for firefly luciferase skyrocketed. Widely used as a genetic “reporter”, luc can be spliced together with any other target gene that scientists might want to study. Whenever the target gene gets activated, luc acts like a spy who reports back by emitting light, which can be quickly and easily measured using sensitive cameras.
Right now, firefly luc is helping us to understand and fight public enemy #1, the SARS-CoV-2 virus that’s responsible for the global pandemic of COVID-19.
A first step to conquering this deadly disease is understanding how the SARS-CoV-2 virus enters and replicates inside host cells. Researchers at Texas Medical Center have studied this process using pseudotyped viral particles. They grafted the S-protein from SARS-CoV-2 onto an innocuous virus, then added firefly luc as genetic reporter. When these pseudo-typed viruses attacked a cultured host cell, luc announced the attack loud and clear: the replicating virus particles emitted light, which could be measured very accurately to determine virus replication rates.
In a completely different application, a research team in Japan has combined luciferase with a fluorescent protein to invent a very sensitive antibody test. Their test quickly detects multiple antibodies using just a tiny drop of blood, and the results are read using a smartphone app. As scientists race to figure out how to treat and prevent COVID-19, it seems that fireflies may help us win this fight.
These beloved insects have given us so much – the gift of wonder + the gift of light. We owe them a huge debt of gratitude, so the least we can do is preserve them for future generations to enjoy. And who knows what other chemical riches lie waiting to be discovered within the firefly pharmacopiea?
“The broken world waits in darkness for the light that is you”
In 2020 the global pandemic of COVID-19 truly broke apart our world. This summer, when our days are filled with anxiety and despair, how can we find the courage to continue doing the work needed to repair the world?
Some people think fireflies are just tiny insects, but for me they’re so much more! They are luminous beings whose natural magic inspires optimism and hope even during the darkest times. That’s why we’ve chosen Hope Rising as the theme for World Firefly Day 2020.
While we celebrate on July 4-5 (also Independence Day in the U.S.), scientists around the world are working hard to develop a vaccine that will protect humanity from this deadly disease. At the same time, we’re working hard to preserve these hope-filled sparks for future generations to enjoy. Even though fireflies have simple needs – water, food, and shelter – they face major threats from loss of suitable habitat, light pollution, and widespread pesticide use.
Here are some simple things we all can do to help fireflies survive:
Protect their homes: help preserve the places where fireflies thrive.
Turn off the lights: too much light at night disrupts firefly courtship.
Don’t use pesticides in your lawn or garden: neonics and other insecticides harm juvenile fireflies.
And please help us spread the word by sharing more tips for creating more firefly-friendly places with others in your Home Owner’s Association, garden club, neighborhood, or town.
Because who’d want to live in a world without fireflies?
Since 2017, the Fireflyers International Network has been sponsoring World Firefly Day, held during the first weekend in July. In previous years, people all over the world have come together to joyfully celebrate the magic and the science of fireflies with festivals, talks, and other events taking place in Malaysia, Thailand, China, Belgium, Mexico, USA, and many other countries. More than mere insects, these luminous beings help keep us connected to Earth’s natural magic.
During 2020, the global coronavirus pandemic has profoundly disrupted our lives. It has taken away loved ones and livelihoods, spread grief and despair, and divided us from family and friends. We wake each day heavy-hearted, weighed down by the gravity of the news. To confront these dark times, we have chosen to center World Firefly Day 2020 around Hope Rising!
Icons of summer, harbingers of monsoons, for centuries these beloved insects have sparked joy and inspired wonder for people all over the world. During these dark times, fireflies also remind us of the great resilience of the natural world, so full of life! So we celebrate them this year as tiny beacons of hope, sparkling lights carrying a promise that humanity will emerge into a brighter future.
Because festivals and gatherings have been cancelled, World Firefly Day 2020 will be celebrated virtually with videos, music, and presentations posted on FIN’s Youtube channel and on FIN Facebook. If you can’t enjoy real fireflies this year, please join our virtual celebration by sharing your firefly stories, poems, photos and artwork with your fellow firefly enthusiasts on FIN Facebook!
When everything has been turned topsy-turvy, tuning in to nature’s rhythms can provide comfort and consolation. With summer camps cancelled and vacations vanished, many of us are preparing to spend this summer at home. So how about a staycation with fireflies? Step out into the night and look for fireflies in your backyard or local park. Camp out with the kids & catch some fireflies in a jar (remember to keep them happy with an apple slice or some damp paper towel). Grab a penlight and practice some lightningbug linguistics. Join the citizen scientists over at Firefly Watch and help us keep track of long-term trends in your local firefly populations.
Stay safe, be well, find joy – we will recover, we will rise up & shine brightly once again!