Last year was the third good summer in a row for butterflies and the 10th best since records began, but one-third of Britain’s species are still in long-term decline.

Conservation scientists warned against overstating the butterfly boom, saying perceptions of a “good” year have lowered in the light of plummeting insect numbers.

“Perhaps because of the sunny spring weather last year and the fact that more people were enjoying nature as part of their day-to-day activities, butterflies seemed more numerous,” said Richard Fox, of Butterfly Conservation. “But in fact our baseline experience of the nature around us has changed over time.”

The UK Butterfly Monitoring Scheme (UKBMS), the most comprehensive scientific insect survey in the world, showed that 2020 had the 10th best summer since 1976, continuing a run of above-average summers. The summer of 2019 was the seventh best, and 2018 the 15th best.

more: https://www.theguardian.com/environment/2021/mar/31/a-good-year-for-uk-butterflies-but-third-of-species-still-in-decline