Hot and dry weather could lead to butterfly ‘population crash’

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.

Professor Richard Fox, head of science at the conservation, said adult butterflies loved hot weather, but warned they 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.