Grapevine

For many in the UK, 2024 was the year without a butterfly

The charity behind the world's largest butterfly survey has declared a national emergency.

Butterfly Conservation's annual Big Butterfly Count, which started in 2010, asks people in the UK to tally the number of butterflies and day-flying moths they see. Over 85,000 volunteers recorded their sightings in 2024, over 25 days between mid-July and early August when conditions for spotting butterflies are usually best.

The results are in. This summer saw the lowest average number of butterflies per 15-minute count in the survey's 14-year history: seven, down from 12 last year. A third of species had their worst summer on record, while more than 9,000 counts reported no butterflies at all.

Comparing butterfly numbers between years is tricky, especially if you only cover part of the season. Some species fly early in the season, others emerge later. Cold weather can delay the development of larvae and reduce butterfly activity while hot and sunny weather can speed it up. This means that the peak of butterfly abundance shifts between years depending on the weather.

A survey limited to part of the season may miss this window. One way of avoiding this problem is to have regular counts throughout the entire season. This is what monitoring schemes such as the UK butterfly monitoring scheme do.