Lights out: can we stop glow-worms and fireflies fading away?
From night walks with children to switching off streetlights and rewilding areas, naturalists are working to save Europe’s dwindling populations An hour or so after sunset, green twinkles of possibility gleam beneath the hedgerows of Westbury-sub-Mendip in Somerset. Under an orange August moon, the last female glow-worms of the season are making one final push at finding a mate.For almost 20 years, Peter Bright and other volunteers have combed the village’s shrubberies and grasslands, searching for the bioluminescent beetles as part of the UK glow-worm survey. Most years, they have counted between 100 and 150, rising to 248 in 2017.Ben Cooke, a National Trust ranger, places a glow-worm trap near Winspit Quarry in Dorset. Photograph: P Flude/Guardian Continue reading...
An hour or so after sunset, green twinkles of possibility gleam beneath the hedgerows of Westbury-sub-Mendip in Somerset. Under an orange August moon, the last female glow-worms of the season are making one final push at finding a mate.For almost 20 years, Peter Bright and other volunteers have combed the village’s shrubberies and grasslands, searching for the bioluminescent beetles as part of the UK glow-worm survey. Most years, they have counted between 100 and 150, rising to 248 in 2017.During last year’s wet summer and this year’s dry one, they found barely 50, says Bright, a retired science teacher taking a group on a late-night glow-worm walk. By August, the remaining lights are something of a lonely hearts club – many of the adult males have already died.Glow-worms and fireflies comprise about 2,200 species of bioluminescent beetles around the world, with 65 found in Europe. The UK has two, including the common glow-worm (Lampyris noctiluca) – which is not a worm and only the females truly glow – while Italy has 17 species.Across Europe, five species of glow-worm are threatened with extinction, another two are endangered, and the common glow-worm is classified as near threatened, according to the International Union for Conservation of Nature.“Once, these things were much more common than they are now,” says Tim Gardiner, an entomologist. “Nobody could have realised what would happen to them.” His 18-year survey found that the numbers of L noctiluca in Essex were falling by about 3.5% a year.Similar trends have been observed in France, Germany and Spain, though the insects, which live quiet, secretive lives in the foliage, are not easy to survey accurately. “There is so much that we don’t know about fireflies,” says Ana Catalán, who researches firefly genomics at Germany’s Ludwig Maximilian University of Munich.Their vulnerability is part of a much larger story: more than 40% of insect species are in decline, according to a global review from 2019, and scientists have warned that the picture may be more dire than is already known.
Ana Catalán, an evolutionary biologist, checks a global firefly collection for a DNA study at the Ludwig Maximilian University of Munich’s biomedical centre, and a researcher checks his trap for fireflies
“We need more data,” says Alan Stewart, an ecologist at the University of Sussex, adding: “We haven’t really got the luxury of waiting another 50 years to find out.”For glow-worms, some of the threats are clear. Hotter summers threaten the slugs and snails they feed on as larvae, while habitat loss and fragmentation have extinguished whole populations. As female glow-worms cannot fly, they are bound to spend their lives close to where they hatched, so a change as seemingly minor as a new ditch can devastate a population.Light pollution disrupts their mating displays, with artificial lights sometimes luring males away from the female’s green glow. “Street lights are a real hazard to them,” says John Tyler, a naturalist who has studied the insects for decades.These trends recur around the world. In Italy, more agricultural activity on the plains of northern Italy and in the northern Apennine mountains has been linked with declining numbers of a range of different species, according to a 2020 study published in the journal BioScience.In Spain, the abandonment of small orchards – and the lack of irrigation that follows – makes it harder for snails, glow-worms’ preferred food, to thrive. In both countries, more streetlights seem to correlate with fewer glow-worms.We realised that to protect and preserve this place, we had to make people love itSome people have attempted to take matters into their own hands. Fabio Falchi, an Italian physics professor and light-pollution expert in Mantua, Lombardy, took steps to reduce light pollution in his garden, including using motion sensors for outdoor lights and allowing it to grow wild.Now, Falchi says: “Every May, our lawn comes alive with their tiny flickers. It’s beautiful to watch them move.” Their cat, he adds, is mesmerised.Others have proposed more drastic steps. Since 2020, Pete Cooper, an ecologist and species-reintroduction specialist in Bristol, has bred glow-worms in captivity, with a view to re-establishing healthy populations in places where they have not been seen for decades.As part of a partnership between Restore, an ecological restoration business, and the Wildwood Trust, a conservation organisation with parks in Kent and Devon, many of these insects will be reintroduced to Nosterfield nature reserve, near Ripon in North Yorkshire.But it will take years to determine the success of their efforts – glow-worms have a two-year life cycle – and some optimism is involved, Cooper says. “That’s the thing with glow-worm reintroduction – it’s not as simple as you’d think.”Tyler says: “We don’t know what habitat is good for them, in any detail. You can find sites that look ideal, but if you try to introduce or reintroduce glow-worms, you can never guarantee that they’ll take.”Glow-worm enthusiasts are divided on reintroduction efforts, which they worry may distract from preserving existing populations or embolden developers to build in ancient countryside.“Before you reintroduce something, you really need to know why it disappeared in the first place,” says Stewart. “Otherwise, they’re not going to survive.”Rewilding can help bolster the insects in riverside areas where they already thrive, says Gardiner. “You need to manage the habitats quite well,” he says. “The corridors between them have disappeared in the last 70 years – hedgerows removed, meadows ploughed up.”Areas that have been rewilded sometimes see glow-worm populations boom. In the early 1990s, a group of volunteers in the Italian village of Binasco, near Milan, began reclaiming and revitalising a plot of land between the highway and a local sports pitch.After a few years, they noticed more and more fireflies, says Ruggero Rognoni, a member of the local environmental association.“We realised that to protect and preserve this place, we had to make people love it,” Rognoni says.A first step was inviting local children to come for night walks to see the fireflies with their parents, a tradition that has continued. “That’s how we’ve managed to protect it,” he says.Such walks exist around the world and are growing in popularity. On the glow-worm walk in Westbury, locals linger along country paths, as a barn owl screeches overhead. Over a couple of hours, careful eyes spot almost a dozen female glow-worms waiting at ankle-height.The average glow-worm female lays 100 to 150 eggs – it’s a numbers’ game. You might have a brilliant year, then it might suddenly crashAmanda Bennett, 48, gently pulls a female from the grass and places it on her hand, transfixed by the green glow that spreads across her fingers. “I can’t believe I’ve never seen one before,” she says.Glow-worms were once a far more common sight, especially for people strolling on summer nights.Tyler was first introduced to them about 50 years ago, in a family friend’s garden. “I didn’t even know they were real,” he says.That night, Tyler saw more than he has on any single occasion since. “It was like looking down on a village,” he adds. “All these dots of light.”They have an unusual capacity to captivate people. John Horne, an amateur naturalist, first discovered them in his Hampshire garden about 25 years ago.After observing them for years, including discovering Phosphaenus hemipterus, a rarer species, Horne is more optimistic about their prospects than some. “The average glow-worm female lays 100 to 150 eggs – it’s a numbers’ game,” he says. “You might have a brilliant year, and then it might suddenly crash.”Where many species find it harder to capture the imagination, glow-worms can be a “gateway drug”, as Cooper puts it, for connecting with nature.Tyler says: “If it has to start with something that glows out of its bottom, then so be it.”Find more age of extinction coverage here, and follow the biodiversity reporters Phoebe Weston and Patrick Greenfield in the Guardian app for more nature coverage
