What Is The Big Butterfly Count?

The annual Big Butterfly Count is back for another year, taking place from Friday 18 July to Sunday 10 August 2025. But what is it, and how can we get involved? Here’s what you need to know.

What Is The Big Butterfly Count?

Spearheaded by Butterfly Conservation, the Big Butterfly Count does what it says on the tin: it counts the UK’s butterflies in an attempt to gauge population numbers across different species nationwide.

Taking place every summer, it is the largest citizen-science project of its kind, and involves volunteers from the general public spending 15 minutes outside in a sunny spot, recording the number and type of butterflies they see. No green space is too small: a back garden, a small terrace or balcony with some pot plants, a public park, allotment, or country lane are all important spaces to explore, track and report.

In 2023, more than 135,000 Counts took place across the country. The scientific data collected helps scientists to understand how butterflies and moths are faring, informs conservation projects and government policies, and supports other experts with their research and vital work to protect our planet. It’s not always a pretty picture: the results of the 2024 Big Butterfly Count prompted Butterfly Conservation to declare a butterfly emergency.

Why Are Butterfly Numbers Dropping?

Did you know a group of butterflies is known as a kaleidoscope? It’s an apt name for the rainbow of colours displayed across different species’ wings. Sadly in 2024, however, kaleidoscopes were few and far between.

Data from 2024’s Big Butterfly Count revealed a dramatic drop in populations numbers of the pretty bugs across the UK. Due to an unusually wet and windy spring along with colder temperatures, volunteers spotted just over half the number of butterflies participants spotted in 2023 – a record low in the 14-year history of the Butterfly Conservation’s Big Butterfly Count.

‘Butterflies need some warm and dry conditions to be able to fly around and mate,’ explained Dr Dan Hoare, Director of Conservation at Butterfly Conservation, in 2024. ‘If the weather doesn’t allow for this there will be fewer opportunities to breed, and the lack of butterflies now is likely the knock-on effect of our very dreary spring and early summer.’

It’s not just the dreary weather: there has been an 80 percent decline in butterfly numbers in the UK since the 1970s due to habitat loss, climate change and pesticide use. With populations of butterflies already depleted, the fluttery bugs are even less resilient to the impact of poor weather, resulting in the record low numbers we are seeing this year.

‘The lack of butterflies this year is a warning sign to us all,’ Dr Haore added in 2024. ‘Nature is sounding the alarm and we must listen. Butterflies are a key indicator species. When they are in trouble we know the wider environment is in trouble too.

‘People are telling us that they aren’t seeing butterflies, but simply telling us is not enough, we need everyone to record what they are or aren’t seeing by doing a Big Butterfly Count as this will give us the evidence we need to take vital action to conserve our butterfly species,’ Dr Hoare said.

Get Involved

This year’s Big Butterfly Count runs from 18 July to 10 August, and it’s easy to get involved. Just follow these three simple steps:

1. Download Butterfly Conservation’s butterfly ID chart (also available on the Big Butterfly Count app on iOS and Android). This will help you identify the species you spot.
2. Choose an outdoor space (ideally in the sun), and stay there for 15 minutes, making a note of all of the butterflies and moths you see in that time.
3. Add your counts on Butterfly Conservation’s website or app.

After you’ve logged your own data, you can explore the interactive map to see where else butterfly counters have been taking part across the country, and the species they’ve been spotting.

For more information and to take part, visit bigbutterflycount.org or download the free Big Butterfly Count app.