Butterfly and day-flying moth numbers recorded across Devon and Cornwall this summer have been "very good" - but experts fear prolonged hot and dry weather could lead to a decline.
Nearly 5,000 people took part in the Butterfly Conservation's 2026 big butterfly count in Devon, recording 77,151 insects during the three-week count. It said nearly 3,000 people took part in Cornwall, spotting 47,712.
Head of science at the conservation, professor Richard Fox, said adult butterflies loved hot weather, but said we could be on course "for a population crash".
"The extreme droughts in 1976 and 1995 had severe impacts on butterfly populations, with some species never fully recovering," he said.
The charity said strong butterfly numbers was "likely" down to favourable conditions for caterpillars in spring, followed by the hot, sunny weather enjoyed by adult butterflies during the summer months.
However, it said previous drought conditions across much of the UK may have caused food plants used by caterpillars to wither before they had finished feeding. The charity fears the full impact may not become until next year.
Fox said many species were already under pressure, with 80% of the UK's butterfly populations having declined since the 1970s.
"So many are already struggling for survival, without these extreme weather pressures," Fox said.
He added: "With hot, dry summers and droughts predicted to become more and more frequent due to climate breakdown, degraded habitats and already depleted butterfly populations, some species may be pushed further and faster towards extinction, which is a sombre thought.
"They are, quite simply, less resilient to these events, which means we could be looking at very difficult years ahead."
The charity is urging people to help wildlife recover by planting more trees and shrubs, installing water butts to store rainwater and leaving areas of grass uncut.
The Gatekeeper was the most commonly spotted butterfly in Devon and Cornwall.
The Meadow Brown took the second spot in Devon, followed by the Red Admiral. In Cornwall, the Red Admiral took second spot, followed by the Painted Lady.
Butterfly Conservation said the Painted Lady was one of the standout species with 6,955 recorded in Devon and 6,033 in Cornwall. The migratory butterfly enjoyed a strong year nationally.
Painted Ladies undertake one of the world's insect migrations, travelling from Africa to the UK over several generations, crossing the Sahara Desert and Mediterranean Sea.
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