Lights out: can we stop glow-worms and fireflies fading away?

"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 shrubberries 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. Ben Cooke, a National Trust ranger, places a glow-worm trap near Winspit Quarry in Dorset. Photograph: P Flude/Guardian 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 Catalan, who researches firefly genomics at Germany's Ludwig Maximilian University of Munich."

Volunteers in Westbury-sub-Mendip have monitored glow-worms for almost 20 years, recording counts that range from around 100–150 most years to a peak of 248 in 2017 and falls to about 50 in recent adverse-weather seasons. Globally, about 2,200 bioluminescent beetle species exist, with 65 in Europe; the UK hosts two species, including Lampyris noctiluca. Several European glow-worm species are listed as threatened, endangered, or near threatened by the IUCN. Long-term surveys indicate L. noctiluca declines of roughly 3.5% per year in some areas, with similar trends in France, Germany and Spain. The insects are secretive and hard to survey, and genomic research is ongoing to better understand their vulnerability and conservation needs.

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