Fading into the night: Fireflies are threatened by climate change and light pollution
Aaron Fairweather remembers seeing fireflies for the first time as a child, a swarm of twinkles flashing across the surface of a lake near Saint John, NB, illuminating a summer night.
Fairweather, who uses she/she pronouns, was fly fishing with their father at the time. Now the University of Guelph research associate fears that threats such as climate change and light pollution could wipe out these luminescent insects, depriving future generations of the “magic” they experienced as children.
“It’s really sad to see one of these childhood wonders — these insects that make us say, ‘Isn’t the world incredible? These organisms can produce their own light and see how beautiful the natural world is’ — we’re losing them. “
While the number of fireflies has remained stable this summer compared to last year, the total number of these insects has declined by about 35 percent over the past five decades, Fairweather said.
There are 173 species of fireflies in North America that have been identified by scientists, and 29 have been found in Canada, said Candace Fallon, a senior biologist with the U.S. conservation group Xerces Society, which is lobbying the United States government to declare endangered status. extend to fireflies.
Fallon is the lead author of a study published in 2021 in the journal PLOS One that suggests that up to one in three firefly species are threatened with extinction, and that some species may disappear before they’re even discovered.
Wingless firefly females — and sometimes larvae — are known as glowworms, while the flying beetles — usually male — are known as fireflies.
Among the 173 known species of fireflies is a type of firefly called the black ghost, found in British Columbia. It measures between five and seven millimeters, but not much else is known about this creature, Fallon said.
“(Glowworms) are more cryptic animals,” she said. “(Black ghost) has a lack of data. We don’t know anything about its habitat associations, except that it was found in a forest along a river.”
Fairweather said insect populations are declining worldwide and fireflies are suffering the same fate. What people don’t realize, they said, are the benefits fireflies have for gardens and waterways. The fireflies people see in their summer gardens are the adults of the species with a lifespan of several weeks; the insects spend up to two years underground as larvae.
“(Firefly) grubs are pretty ferocious predators,” Fairweather said. “They will feed on worms and slugs and snails, and especially mosquito larvae in some ecosystems.”
The larvae are unsung and unseen heroes of gardens and waterways because they keep ecosystems clean, they said. So it worries scientists when a warming planet dries out the Earth and scorches forests, or when human activity fills swamps to create buildings – these little animals’ homes are destroyed.
In the village of Nanacamilpa, fireflies help save the towering fir and fir trees on the outskirts of Mexico City. Thousands of them light up a magical display at dusk in the primeval forests on reserves such as the Piedra Canteada Park, about 75 kilometers east of the Mexican capital.
Piedra Canteada in the state of Tlaxcala is not a government-run park, but a rural co-op that, with the help of the fireflies, has emerged from poverty and dependence on logging. For years, economic forces, including low prices for agricultural products, forced rural communities like Piedra Canteada to cut down trees and sell the logs.
Then, in 2011, community members realized that the millions of fireflies that appear between June and August could attract tourists from larger cities where few people have seen them in large numbers. Camping spots are now selling out weeks in advance for families coming from all over the world.
“Glowworms can be a huge source of ecotourism,” Fairweather said. “From May to June in Canada you can go to most swamps or fields and see thousands. I think it’s just an incredible model that hasn’t been tapped yet.”
Light pollution, Fallon said, is one of the biggest threats to firefly populations, especially since 75 percent of these insects are active at dusk or after dark. Fireflies use their light to find a mate, she said.
Glowworm species have different twinkling patterns: some give off quick flashes of flashing light, others have a flash of light and go dark; female glowworms, meanwhile, emit a soft shimmer as the male swoops in to look for a mate, she said.
But this courtship is interrupted by bright artificial light, such as that from buildings, porches or even passing vehicles, which can drown out the signals these insects use to communicate and find each other, ultimately affecting the species’ reproduction, Fallon said.
In Muskoka, Ont., Fairweather said the local government has asked residents this year to turn off porch lights when not in use, to help fireflies.
There’s a painful lack of basic data on fireflies, Fallon said.
“They are so famous, there is so much nostalgia around them. … But they are a little bit different,” she said.
“People just think of them as these magical creatures that light up the night. But don’t link it to the fact that they’re part of our biodiversity.”
Fairweather said funding for firefly research is hard to come by because of an “absence of thought.”
“It’s ‘oh, this is just a childhood staple. It will always be there,” they said.
“Who knows? Maybe we won’t be able to show examples of fireflies in another 20 to 50 years. We have these stories, but where are these organisms now? Or are they a myth?”
This report from The Canadian Press was first published on July 15, 2023.
— With files from The Associated Press.
