A groundbreaking study using Met Office weather radar data has revealed a sharp decline in nocturnal insects across the UK, raising new concerns about light pollution and climate change.
Scientists from the University of Leeds repurposed data from 15 weather surveillance radars, originally designed to track rain and clouds, to monitor the trillions of insects flying over Britain each year. Between 2014 and 2021, the team found that while daytime insect activity stayed stable or increased in the south, night-flying insects – such as moths – declined significantly, particularly in northern regions.
“This is one of the first studies to show how day- and night-flying insects are being affected differently,” said Dr Mansi Mungee, who led the research. “It’s a crucial step toward understanding where to focus conservation efforts.”
On average, researchers recorded 11.2 trillion insects flying during the day and just over 5 trillion at night between 500 and 700 metres above ground. Abundance was highest in woodlands, grasslands and urban areas, but dropped sharply in intensively farmed regions and light-polluted zones.
Artificial lighting, particularly from brighter modern bulbs and car headlights, is likely worsening nocturnal declines. “It could be a blip, but we are changing how we light the night,” said co-author Dr Christopher Hassall.
The data also showed a north-south shift in insect populations linked to the climate crisis, with northern species declining as conditions grow warmer and drier. Southern species may eventually replace them, though not immediately.
The findings, published in Global Change Biology, highlight how technology designed for weather forecasting can also reveal critical trends in biodiversity loss — and the growing pressure on ecosystems from both human activity and climate change.
