Insects Gather at Lights Because They're Confused

Moths and other flying insects end up fluttering around artificial lights at night not because they find the light itself appealing, but because the light messes with their navigation systems, researchers say. Sam Fabian, co-author of a study published in the journal Nature Communications, says moths and other insects appear to instinctively tilt their backs toward light as a way of reorienting themselves after swooping around because the sky is lighter than the ground, even at night, NPR reports. "It's extremely smart because it's very finely tuned and it works beautifully until somebody invents the lamp or the light bulb," says Fabian, an entomologist at Imperial College London

Researchers attached sensors to moths and dragonflies for motion-capture video of the insects' flight, the AP reports. They observed confused insects circling lights for hours. Harvard entomologist Avalon Owens, who studies the effect of artificial light on insects but was not involved with the study, says the discovery is exciting. "We've probably been wondering why moths fly to lights since the invention of fire," Owens tells NPR. "The fact that after, like, literally millennia we have a new observation on this very old phenomenon is just absolutely buck wild to me."

Fabian says the research suggests that artificial light doesn't attract insects from the surrounding area, but traps those that fly by, the Guardian reports. "It's almost like having a net," he says. Light pollution is thought to be among the causes of steep declines in insect numbers and Fabian believes the study could assist conservation efforts. The research found that insects are less confused by lights that are pointing down. "If you are going to have lights at night, you really want them to be shrouded and not chucking loads of light out sideways, and especially not upwards into the atmosphere," he says. (More insects stories.)