\u201cInsectageddon\u201d has not occurred, but there has been a loss of butterfly diversity over the past half a century, according to the world\u2019s largest insect monitoring scheme.<\/p>\n
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.<\/p>\n
Global heating is proving a boon to some butterfly species: the purple emperor (up 136%<\/a>), red admiral (up 330%) and comma (up 178%) are moving northwards through Britain owing to warmer weather.<\/p>\n A purple emperor in the Malvern Hills. Photograph: Ian Henderson\/Guardian Community<\/p>\n But a number of rarer, \u201chabitat specialist\u201d butterflies \u2013 which rely on specific plants or habitats such as wetlands, woodlands or flower-rich grasslands \u2013 have sustained serious declines, including the high brown fritillary (down 66%), pearl-bordered fritillary (down 70%) and white-letter hairstreak (down 80%).<\/p>\n \u201cIt\u2019s not the insect Armageddon<\/a> picture that was put forward a few years back,\u201d said Richard Fox, the head of science at Butterfly Conservation<\/a>. \u201cBut 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.\u201d<\/p>\n 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.<\/p>\n White-letter hairstreaks have declined by 80%, figures show. Photograph: Peter Eeles\/Butterfly Conservation\/PA<\/p>\n 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.<\/p>\n \u201cThe rain is now dilute fertiliser and that\u2019s raining down on our plant communities and causing them to change,\u201d Fox said. \u201cChanges in the composition, structure and even chemical makeup of plants is bound to have knock-on effects on specialist herbivores like our butterfly caterpillars.\u201d<\/p>\n 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. \u201cWe just need to do a lot more of it,\u201d he said.<\/p>\n