Butterfly numbers have seen a sharp decline this summer, according to a new study.

Butterfly Conservation, a charity, conducted a count at Yorkshire Wildlife Trust reserves during June and July.

Co-ordinator Nick Hall called the findings “shocking,” with early data showing that butterfly abundance had dropped to less than half of what was recorded in the same period of 2023.

In 2023, 13,007 butterflies were observed across 12 Yorkshire sites, but only 6,078 were counted this year.

Mr Hall added: “Frighteningly, three-quarters of our species are down more than two-thirds, and a third are down 90%.”

Some species, such as the holly blue, small copper, common blue, and brown argus, were not spotted at all.

Dr Dan Hoare, director of conservation at Butterfly Conservation, said butterflies need “warm and dry conditions to be able to fly around and mate”, so 2024’s “very dreary spring and early summer” had left the insects with “fewer opportunities to breed, and the lack of butterflies this year is likely the knock-on effect”.

However, there were positive signs for certain species.

“The exception to this trend was the peacock butterfly, which suffered in the previous year’s heat but has started to recover this year,” Mr Hall said. “The damp-loving ringlet also bucked the trend.”

Hall noted that the long-term trend suggested 2024’s low numbers might be a “blip.”

He explained that since the 1980s, each decade has grown warmer, with the last 10 years including two of the hottest summers, leading to an increase in butterfly populations overall.

For example, 8,397 butterflies were recorded in 2021 and 10,097 in 2022, with species like the silver-washed fritillary benefiting.

The conservationist added if temperatures continued to rise, “we can hopefully expect 2024 to be a blip and Yorkshire to continue seeing species expanding their range northwards into our region and increasing their abundance”.

Mr Hall said new species were arriving in Yorkshire “at a rate of one every four years, as they have for the last 40 years”.

However, Dr Hoare added the lack of butterflies this summer was also “a warning sign to us all”.

He said butterflies were “a key indicator species and when they are in trouble we know the wider environment is in trouble too”.

 

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