A summer of soaring temperatures could spell trouble for Britain’s butterflies in 2027.
Despite strong numbers recorded during the 2026 Big Butterfly Count, experts at Butterfly Conservation, based in Dorset, warn that drought conditions could have harmed caterpillars, potentially leading to a decline in adult butterflies next year.
Professor Richard Fox, head of science at Butterfly Conservation, said: "This has been one of the hottest, driest summers on record, and the figures certainly suggest that was good news for many of the widespread butterfly species monitored by the Count.
"In fact, it was the second-best year in the 16-year history of the Big Butterfly Count.
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"Adult butterflies love hot, sunny weather for flying, feeding and breeding, and that's exactly why people saw so many this summer.
"But a good summer for adult butterflies is not the same as a good summer for butterfly populations.
"What matters far more is what's happening on the ground, to the butterflies’ caterpillar offspring and the plants they depend on.
"The very same weather that made it a good year for butterflies – lots of sunshine and very little rain – could mean we’re actually on course for a population crash, which could take years to recover from."
More than 101,000 people took part in the 2026 count, recording nearly 1.4 million butterflies and moths across the UK.
Holly Blue and Gatekeeper butterflies reached their highest-ever totals, while the Small Copper had its third-best year.
However, the Small Tortoiseshell recorded its second-worst result, down 66 per cent since the count began.
Species sensitive to drought, such as the Speckled Wood, Green-veined White, and Ringlet, were seen in below-average numbers and have shown long-term declines of 44 per cent, 54 per cent, and 39 per cent respectively since 2011.
Butterfly Conservation fears the full impact of this summer’s drought will become apparent next year.
Many caterpillar food plants dried up before larvae finished feeding, raising concerns about survival rates.
Professor Fox said: "Our real worry isn't this summer, it's what happens next.
"We’ve been here before and it’s not good; the extreme droughts in 1976 and 1995 had severe impacts on butterfly populations, with some species never fully recovering."
The charity is urging the public to take action by planting more trees and shrubs, installing water butts, and leaving patches of grass uncut to provide shelter and food for caterpillars.
The next Big Butterfly Count will take place from July 9 to August 1, 2027.
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