33 Out Of 58 Butterfly Species Native To The UK In Decline; Along W. Habitat Loss, Warming Taking Its Toll

“Insectageddon” has not occurred, but there has been a loss of butterfly diversity over the past half a century, according to the world’s largest insect monitoring scheme. More than 44m butterfly sightings scientifically collected in Britain since 1976 show that of the 58 native species recorded, 33 species have declined and 25 have increased in number.

Global heating is proving a boon to some butterfly species: the purple emperor (up 136%), red admiral (up 330%) and comma (up 178%) are moving northwards through Britain owing to warmer weather. But a number of rarer, “habitat specialist” butterflies – which rely on specific plants or habitats such as wetlands, woodlands or flower-rich grasslands – have sustained serious declines, including the high brown fritillary (down 66%), pearl-bordered fritillary (down 70%) and white-letter hairstreak (down 80%). “It’s not the insect Armageddon picture that was put forward a few years back,” said Richard Fox, the head of science at Butterfly Conservation. “But the data show very clearly that butterflies have declined in the UK over the last 50 years, and in particular habitat specialist butterflies have declined.”

Pearl-bordered, small pearl-bordered and high brown fritillaries have all become rare butterflies because of the loss of traditional woodland management such as coppicing over the past century, which has reduced the floral-rich, sunny character of many woods.Habitat loss and pollution are driving declines, but global heating is often playing an indirect role.

According to Fox, the grassland-dwelling wall brown and grayling are likely to be vanishing because a combination of warmer weather and nitrogen pollution mainly from vehicles is causing grass to grow taller, making it too cool for some caterpillars to thrive. “The rain is now dilute fertiliser and that’s raining down on our plant communities and causing them to change,” Fox said. “Changes in the composition, structure and even chemical makeup of plants is bound to have knock-on effects on specialist herbivores like our butterfly caterpillars.” Rare and declining habitat specialist butterflies have been well-studied. Fox said conservationists generally knew what kind of conservation management could boost numbers of the declining species. “We just need to do a lot more of it,” he said.

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https://www.theguardian.com/environment/2026/apr/15/butterfly-monitoring-scheme-britain-decline