At six rural railway stations in Germany's Dark Sky Reserve, a place where the night sky stays as dark as nature intended, scientists have found a surprisingly simple fix for a big problem.
Insects are in trouble. About 40% of all insect species worldwide are declining and could disappear entirely. Habitat loss, pollution, climate change, and artificial light all play a role. Streetlights and security lamps are especially harmful. Moths, beetles, and other bugs get drawn to these lights, circle them for hours until they drop from exhaustion, or become easy targets for predators. The lights also confuse insects, pulling them away from important tasks like finding food, mating, and moving through their ecosystems.
Researchers at the Leibniz Institute for the Analysis of Biodiversity Change in Germany wanted to see if changing the type of light could help. Led by Carmen Ludreschl and colleagues, the team tested three different kinds of outdoor lighting at six railway stations. Over two field seasons in 2023 and 2024, they compared the lights and measured what insects were attracted using traps.
The results were striking. Warm amber LED lights, set to a color temperature of 1800 K, attracted 39% to 51% fewer insects than conventional high-pressure sodium lamps and cool-white LEDs. The total weight of insects caught under these amber lights dropped even more dramatically, falling by 51% to 77%. The researchers called this the "clear winner" among the options tested.
One finding that surprised the team: traditional high-pressure sodium lamps, which glow with a warmer orange tone, attracted just as many bugs as cool-white LEDs. This challenges the idea that any warmer-looking light is automatically safer for insects. The color temperature and exact wavelength matter more than simply how "warm" a light appears to human eyes.
The amber lights are not a perfect solution. The study found that even these LEDs still drew more insects than completely unlit areas. Any artificial light causes some harm. But the researchers note that making improvements where we can still counts for something.
Practical change has already followed the research. Based on these findings, platform lighting at all six railway stations in the German Dark Sky Reserve has been converted to 1800 K LEDs. It is a small switch that could make a real difference for bug populations struggling to survive in an increasingly bright world.