Butterflies on the Isle of Wight could face a difficult 2027 despite large numbers being spotted this summer, with conservationists warning that drought-starved caterpillars could lead to a population crash next year.
Butterfly Conservation says the hot and dry conditions which helped adult butterflies thrive during 2026 may have had the opposite effect on their offspring.
The warning has particular relevance on the Isle of Wight, where the effects of drought on butterfly populations were already causing concern following the hot and dry conditions of 2025.
As previously reported by Island Echo, no dark green fritillary butterflies were recorded on Mottistone Down during monitoring in 2025, despite the species usually being seen there in good numbers.
This is due to its food plant, the hairy violet, being particularly sensitive to drought.
There was better news for the Adonis blue, which had a better-than-average year at Compton and Mottistone Downs, helped by the success of horseshoe vetch earlier in the season.
However, Isle of Wight countryside experts warned at the time that the later drought could damage the plant and subsequently affect butterfly numbers.
Now Butterfly Conservation has issued a wider warning following another exceptionally hot and dry summer.
The charity’s 2026 Big Butterfly Count saw 101,565 participants record almost 1.4million butterflies and moths across the UK, making it the second-best year in the Count’s 16-year history.
Holly Blue and Gatekeeper recorded their best-ever results, while Small Copper had its third-best year.
Painted Lady numbers were up 335% compared with last year, while the Small White was the most commonly recorded species, with 281,634 sightings.
However, some species known to be sensitive to drought continued to struggle. Speckled Wood, Green-veined White and Ringlet were all recorded in below-average numbers.
Small Tortoiseshell also experienced its second-worst year since the Big Butterfly Count began and has declined by 66% since 2011.
Professor Richard Fox, Head of Science at Butterfly Conservation, has 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!
“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.”
Butterfly Conservation says many of the plants caterpillars depend upon withered or died before the insects had finished feeding this summer.
The consequences may therefore only become clear in 2027, when those caterpillars would otherwise be expected to emerge as adult butterflies.
Professor Fox added:
“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.
“And the major problem we have now is that 80% of the UK’s butterflies have declined since the 1970s, so many are already struggling for survival, without these extreme weather pressures.”
Islanders are being encouraged to make gardens and outdoor spaces more resilient to drought by planting trees and shrubs such as holly, ivy and buckthorn, collecting rainwater in water butts and leaving areas of grass to grow long.
Research by Butterfly Conservation found gardens containing patches of long grass saw up to 93% more butterflies and a greater range of species.
Longer grass develops deeper roots and can remain green for longer during drought, while also providing food for the caterpillars of butterflies including Speckled Wood, Meadow Brown and Gatekeeper.
More information about helping butterflies can be found at www.butterfly-conservation.org.
