Over the past 50 years, butterfly populations in the United Kingdom have recorded demographic declines, with 2024 being the worst year on record. Scientists are calling on people to stop mowing their garden lawns to help butterflies recover.
In 1976, the organisation Butterfly Conservation launched a monitoring programme on the state of butterfly populations in the United Kingdom. Thanks to the help of numerous volunteers, it was possible to carry out monitoring across as many as 3,552 sites. The results revealed that out of 59 butterfly species, as many as 31 have recorded a numerical decline. More than half of all butterfly populations are in decline. What's more, the situation has worsened, with 2024 going down as the worst year for butterfly numbers across the entire country. Last year, only 8 out of 59 species did not suffer demographic losses.
The numerical results of butterfly monitoring can vary from year to year, primarily because individual species populations fluctuate according to annual weather conditions. For example, 2024 was characterised by a wet spring followed by a relatively cool summer. One of the main causes of this decline, according to the experts responsible for the programme, is ourselves — humans — and the way in which we manage the landscape. In short: habitat destruction and the use of pesticides and pollutants. However, climate change is also making unusual weather conditions increasingly frequent.
In 2024, many butterfly species recorded demographic declines, and for nine species in particular — including Pyrgus malvae, Leptidea juvernica and Polyommatus coridon — last year was the worst on record, with severe losses. Among other species that have suffered significant long-term losses is Aglais urticae, which has crashed by 86 per cent over the past 49 years, and Pieris napi, which has declined by 28 per cent. For more common butterflies — those found in gardens, parks and rural areas — 2024 was their second worst year. Among these, however, 6 species showed an increase in numbers since 2023.
Richard Fox, doctor and head of science at Butterfly Conservation — the group that carried out this monitoring — has stated that when butterflies are in decline, there are certainly problems with the environment, as they are important indicators of environmental health. Indeed, the use of pesticides and the loss of biodiversity-rich habitats is bringing butterfly populations — and not only them — to their knees.
Climatic conditions also influence butterfly populations. In adverse weather, already weakened populations become extremely vulnerable and are unable to recover. Continuing, Fox offers a note of hope: "This situation is reversible." Change is possible, he urged people to let their gardens grow wild and free, allowing the grass to grow tall during summer so as to create an ideal environment to increase both the number and variety of butterflies.
Even if we don't realise it, the small gestures we make every day have an effect on the world around us. Allowing nature to recover, simply by tending to our own home garden in the right way, is within our reach. The survival of countless organisms can depend on us too.