The number of butterflies in the UK has plummeted to the lowest ever level since records began.
A study of butterfly and moth populations in this year’s annual Big Butterfly Count found they were down by 14 per cent compared to 2020.
While the majority of butterfly species have been in long-term decline since 1976, conservationists from Butterfly Conservation believe the insects were hit especially hard by an unseasonably cold and wet spring this year.
Julie Williams, the charity’s chief executive, said “urgent action” needs to be taken.
She said: “The facts are clear. Nature is in crisis and we need urgent action, not just to prevent further species losses but to rebuild biodiversity.”
Of the 150,000 counts registered during this year’s survey, people recorded nine butterflies or moths per count on average, down from 11 in 2020, and 16 in 2019.
A total of 1,238,405 butterflies and moths were counted between 16 July and 8 August, down 14 per cent on last year.
The peacock butterfly suffered its lowest numbers since 2012 as it dropped by 63 per cent, while the small tortoiseshell, once a frequent visitor to gardens in the UK, had its third-worst summer as numbers fell by 32 per cent.
Other species to see a significant decline in numbers were the comma (32 per cent), holly blue (58 per cent) and speckled wood (41 per cent).
The marbled white and ringlet, which rose by 213 and 81 per cent respectively, appeared to bounce back from 2020, however scientists at the charity said last year’s unusually sunny spring allowed them to emerge earlier and this year’s results were therefore more typical for these species.
Dr Zoe Randle, senior surveys officer at Butterfly Conservation, said May’s wet weather would have hindered butterfly feeding and breeding, especially for species that produce two broods a year.
She said: “The majority of these double-brooded species experienced their worst year since the start of the Big Butterfly Count in 2010. Weather changes are likely to be the cause of this.
“March 2021 was warmer than average which would have stimulated butterfly activity. However, May was very wet which will have hampered butterfly feeding and breeding.
“These combined weather effects are likely to have reduced the spring generation which has knock-on effects for the second generation in the summer.”
With extreme weather events expected to become more likely because of climate change, the charity has warned the impact on some of the UK’s most loved insects could be “devastating”.
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