Skip to Content

Impact of nitrogen pollution on butterflies and moths revealed in new study

News Item 2025

A new study by JNCC and the UK Centre for Hydrology & Ecology (UKCEH) has revealed how atmospheric nitrogen pollution is affecting butterfly and moth populations across the United Kingdom (UK).

The results found clear links between nitrogen pollution and changes in Lepidoptera (butterfly and moth) populations, though the relationships are more complex than previously thought.

Atmospheric nitrogen pollution is a leading cause of biodiversity loss globally, however there is a lack of published evidence regarding how nitrogen pollution affects Lepidoptera species in the UK. Our recently published research provides the first comprehensive baseline for understanding how nitrogen pollution affects our native insects.

The study showed there was strong evidence that numbers of butterfly species had declined in areas with high levels of nitrogen pollution in the 1990s, yet the overall total number of butterflies was not affected.

Moths displayed more complex patterns. Increased moth numbers as well as increased total numbers of moth species were found where nitrogen levels have declined, but areas with high historic pollution from the 1990s tended to have higher numbers of moth populations overall.

The research highlights that more work is needed to fully understand the potential effects of nitrogen on moths in the UK. 

Importantly, it found that different moth species may respond very differently to nitrogen. Some species struggled with increased nitrogen levels whilst others appeared to thrive.

The findings provide a baseline understanding for the effects of nitrogen pollution on Lepidoptera species in the UK. In the future, this could inform the development of a new air pollution recovery indicator for Lepidoptera species, crucial for monitoring ecosystem health and guiding future conservation efforts.

The data underpinning the study was taken from long-term monitoring schemes such as the UK Butterfly Monitoring Scheme and the Rothamsted Insect Survey, both which have been established for more than 50 years.

The UK Butterfly Monitoring Scheme is run in collaboration with Butterfly Conservation, the UK Centre for Hydrology & Ecology, and the British Trust for Ornithology. It is one of JNCC’s 11 schemes that monitor species throughout the UK. Monitoring schemes are critical to helping us understand how nature is faring and whether policies impacting conservation are being successful. These insights on the impact of policies on species, combined with other monitoring data, will also enable us to project the likely impact of conservation polices and the effectiveness. 

Back to top