Do moths fly into the light? Street lighting can endanger insects.

Insect-friendly lighting along roads can significantly reduce the number of insects dying. According to the Karlsruhe Regional Council, a research project found that the number of insects attracted to light, such as butterflies, cicadas, flies, and lice, was roughly halved after test routes were equipped with specially targeted lights.

The decisive factor in the experiments was that, with the help of shielded LED lighting, light was directed only where it was actually needed. For example, onto a footpath, but not into the surrounding landscape.

"The additional benefit of a reduced color temperature of the new LED lighting could not be clearly demonstrated in this study," said Dominique Erb, who oversees the "NaturLicht" project at the Karlsruhe authority. However, other studies show that this also attracts fewer insects.

According to Erb, this is why municipalities recommend choosing a shielded LED variant with a low color temperature—warm white or amber—when retrofitting streetlights. This is particularly important in close proximity to valuable habitats such as nature reserves.

About the study: Experts from the Light Pollution and Ecophysiology research group at the Leibniz Institute of Freshwater Ecology and Inland Fisheries (IGB) set up traps in three nature reserves in Baden-Württemberg. They wanted to collect data on the species and number of insects buzzing into them.

Half of the lights were converted to LEDs and fitted with shields. This allowed the light to be limited so that it was only visible on sidewalks and streets, but not radiated into the bushes to the left and right. The unaltered lights served as a comparative control. "At the end of the test, the entire test track was modernized," says Erb.

The new lights would also significantly reduce the negative impacts of artificial lighting on important ecosystem functions such as nighttime pollination, she explained. "Applied on a large scale, this will also contribute to a reduction in artificial sky brightness."

There's also a fundamental conflict behind the project: On the one hand, street lighting is intended to ensure the safety of citizens at night. On the other hand, it has negative consequences for animals: insects, for example, are attracted, removed from their natural habitat, and die from the lighting.

The issues of light pollution and insect extinction are not new. Lighting has also been converted to protect insects in other places. Cologne Cathedral, for example, has been illuminated by more than 700 LED lamps since April, replacing halogen lamps. According to the information, the most effective lighting concept is intended to keep light pollution to a minimum and protect the cathedral as a habitat for insects and other animals.

In 2022, a pilot project was launched in Heiningen, at the foot of the Swabian Alb, in which lights along the town's main road were dimmed depending on traffic volume. This was determined using cameras, real-time traffic data, high-resolution microphones, and Bluetooth trackers.

And in the Baltic Sea resort of Ahrenshoop, 15 red-light lanterns equipped with side screens were put into operation along a street last year. Instead of bright white, they glow yellow-orange at dusk and red at night. "Insects generally cannot see red light," project manager Annett Storm explained at the time.