Who turned out the light? Fireflies seem to be disappearing

Fireflies in Ottawa drew unusual attention last summer. They winked through backyards and across parking lots in numbers high enough to prompt a flicker of hope that maybe, after smoke-filled skies and erratic temperatures, nature was bouncing back.

Less than a year later, the same insects are harder to find. Reports warn they’re disappearing; some suggest children born today might be the last generation to see them. The science behind those claims is limited, but the fear points to something real: if fireflies are vanishing, we might not know because we haven’t kept count.

Blink and they’re gone

Patrice Bouchard has catalogued beetles for two decades as an entomologist at Agriculture and Agri-Food Canada. His work, like much federally driven insect science, follows a risk-based approach, prioritizing what threatens crops or might slip across borders. A triage model is more likely to sideline harmless creatures like the firefly.

“We typically (study) those that affect agriculture the most,” Bouchard said. “For example, there’s a national project monitoring wireworms to help farmers. I don’t know of any similar project for fireflies, unfortunately.”

Of the 8,300 beetle species documented in Canada, 32 are in the Lampyridae family that includes fireflies. None are currently listed as at risk — federally or provincially — not because they’re thriving per se, but because the data isn’t there. “As of five years ago, the national body that oversees conservation status did not have many fireflies on their radar,” he said. “We’ll see if that changes in the next Wild Species report.”

Fireflies were included for the first time in the 2020 edition of the report, which listed three species as vulnerable and four as unrankable due to data gaps, according to Environment and Climate Change Canada. The next report is expected in 2026.

When fireflies don’t emit light or don’t fly, they’re less likely to be counted, much less studied. “Not all species have the flashing organs in adults, and they don’t always use them the same way,” said Bouchard. “Observations tend to focus on a small handful.”

Fluctuations in abundance aren’t unusual in the insect world, he added, and can reflect weather more than extinction risk. But lack of formal monitoring means we may miss a decline — a pattern that has already played out.

Lady beetles were once as common and beloved as fireflies. Several Canadian species are now endangered after being edged out by aggressive invaders. “You’re much more likely to see the multicoloured Asian lady beetle. A lot of native ones are barely around,” said Bouchard.

He’d prefer not to see that outcome repeated with fireflies.

“They are really cool beetles, and I would not like to see them disappear,” he said. “By losing biodiversity, we might lose tools that we are borrowing from nature.”

Beyond their ecological role as predators of garden pests and invasive worms, fireflies have advanced drug screening, cancer research and the study of infectious disease. Their glow, powered by cold bioluminescence, is a natural mechanism from which scientists are still learning.

The light-emitting beetles are also a cultural touchstone and a practical entry point for public involvement in preservation.

iNaturalist, a phone app that lets users upload insect photos for expert identification, has worked its way into Bouchard’s workflow. His team used it to document a non-native beetle in Halifax. It’s also one of the few ways researchers can monitor firefly sightings in Canada. “We can’t be everywhere,” he said. “The public can help fill in what’s missing.”

Unless more consistent monitoring tools are developed, Bouchard said, or citizen science picks up the slack, fireflies could fade out of view before science catches up.

Enter the glow chasers

Candace Fallon spends her summers knee-deep in undergrowth, surveying butterflies in Nevada and searching for fireflies in places like Arizona and Idaho. A senior conservation biologist with the Xerces Society, she leads the nonprofit’s firefly conservation work under its endangered species program — one of the only coordinated efforts of its kind in North America.

“We kept hearing reports from all these people about seeing fewer fireflies,” she said. “And we wanted to know, is that the case? Is there data to back this up?”

What they found was less reassuring than a simple yes. “We don’t have baseline data for any firefly species in the U.S. or Canada, which makes it hard to know the extent of that loss, if there is indeed a loss,” said Fallon.

Fallon helped coordinate a 2021 firefly assessment with the International Union for Conservation of Nature’s Firefly Specialist Group, analyzing 132 species across the continent. Eighteen were deemed at risk of extinction. Two more were considered near threatened. More than half couldn’t be properly assessed because the data was too thin to make the call.

The lack of long-term records is a blind spot across much of insect science — a field where boom-and-bust cycles can camouflage steady decline. “That’s what makes long-term data sets so important,” said Fallon. “You want to be able to see this longer trend over time.”

Even spectacular sightings can mislead. Ottawa’s apparent firefly resurgence last summer may have had more to do with rainfall than population health. “They are reliant on moisture,” said Fallon. “If you have more precipitation the season prior, that can influence a larger population the following season.”

The drivers of long-term decline, by contrast, don’t come and go with the weather. “You have everything from loss of habitat through development, pesticide exposure, herbicide use,” said Fallon. “And then a big one in urban areas, particularly, is light pollution.”

Fireflies use flash patterns to find mates. When those signals are drowned out by porch lights or street lamps, they lose the ability to see each other and reproduce. Some dusk-active species, like the big dipper firefly, may be more adaptable. But others emerge only in full darkness and don’t stand a chance. “It can flood their sensory system,” Fallon said.

She documented those threats in “Conserving the Jewels of the Night,” a collection of guidelines aimed at well-meaning homeowners who might destroy insect habitat by accident. Firefly larvae develop underground or in leaf litter for up to two years and rarely stray far from where they hatch. Strip the soil bare, and there’s nothing left to grow up.

“We always say, ‘keep spaces a little messy,’” Fallon said. “You might be raking up all of your baby fireflies and throwing them away.”

Saving fireflies means turning off lights, laying off the pesticides and resisting the urge to manicure every square inch of your yard. Most people don’t realize their landscaping choices could erase an entire generation of beetles — or that the adults they admire each summer are only a fraction of the picture.

You might be raking up all of your baby fireflies and throwing them away.

Candace Fallon

Fallon regularly directs the firefly-curious to the Firefly Atlas, a community science platform that invites people to track sightings across the U.S. and Canada. And while the data is still patchy in places like Ottawa, she sees that as an invitation.

“People are starting to realize, hey — we should be concerned about our firefly populations,” she said. “And start to do something about it.”

Lighting up data gaps

Conservation biologist Richard Joyce has counted fireflies in pitch-black fields and wetlands at dusk, watching their flashes stutter through the dark like Morse code. To him, it is a kind of language.

“There are 22 species of firefly in Ontario,” he said. “Eight species have evolved to be active during the daytime and have lost the ability to produce light.” Of the 14 that still glow, flash pattern and colour can separate one from the next.

“If you go out into a wet meadow, you might be seeing four or five species at once,” he said. “Our first goal is to better map where different species are found.”

Joyce coordinates the Firefly Atlas to establish species-level records. “There have been some efforts in the past to count and monitor populations, but in some ways that’s jumping the gun,” he said. “It’d be kind of like going out and counting birds, but not distinguishing between a crow and a bald eagle.”

The Atlas trains participants to note flash rhythms, habitat and time of night — and to submit close-up photos from above and below. “For many species, we can confidently identify what type of firefly it is,” he said. “We want to make sure we’re maintaining the full diversity, not just keeping some fireflies out there.”

Contributors are also asked to estimate abundance. “Do you see just one firefly? More than 50?” he said. That begins to shade in the map like a field coming to life at dusk.

Joyce doesn’t want people to mistake blank spots on the Atlas for absence. “With iNaturalist, you just get a point where someone submitted a photo, it doesn’t show you absence,” he said. “But with Firefly Atlas, we track effort. You can report that you didn’t see fireflies.”

A lack of nighttime access adds to the blind spots. “So many great habitats aren’t accessible at night,” said Joyce. “There are so many places where we can hike and birdwatch during the day, but it’s closed at night. Even conservation land managers… have very little sense of what’s going on at night because at night they just go home.”

For Joyce, public curiosity is a practical solution. “I think that fireflies can capture the imagination and curiosity of everyone,” he said. “And I think that’s one of the things that makes them wonderful ambassadors for insects.”

But it only works if people show up. “We just need many more people in many more places paying attention.”

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