Butterfly numbers in the UK have recovered from the dismal summer of 2024, but the hottest summer on record only brought numbers back to average levels, according to the annual Big Butterfly Count. More than 125,000 citizen scientists took part in the world's largest insect survey, counting an average of 10.3 butterflies per 15-minute session in parks, gardens, and green spaces across Britain.
This marks a significant improvement on 2024, when a record low of just seven butterflies per count were recorded. The large white butterfly saw a 131% increase in sightings compared to last year, while the small white and red admiral rose by 128% and 185% respectively. However, Butterfly Conservation warned that numbers have only returned to average, with higher counts recorded in 2023 and every summer from 2016 to 2020.
Dr Richard Fox, head of science at Butterfly Conservation, said: “We may feel like we’ve seen lots of butterflies this summer, but that’s only because last year was so awful. The 15-year Big Butterfly Count trends show that more than twice as many widespread species have declined significantly than have increased. And while most species had a better-than-average summer, one-third of species fared poorly even in the generally beneficial weather.”
The large and small whites achieved their best-ever results in the count, and the day-flying Jersey tiger moth was recorded more widely and in higher numbers than ever before. However, the holly blue had its second-worst result, and the meadow brown its fourth-worst, possibly due to an earlier flight season. The small tortoiseshell bounced back from its worst-ever result in 2024 but has still declined by 60% since 2011.
Over the 15-year period, some species have shown long-term increases, including the large white, red admiral, and small copper. Fox emphasised the need for urgent action to support butterfly populations, including habitat restoration and reduced pesticide use, stating: “Until we do these things we are unlikely to see a great recovery in butterfly numbers, regardless of how much the sun shines.”
