WASHINGTON (AP) — Like a flaming moth, many scientists and poets have long assumed that flying insects are simply and inexorably drawn to bright lights.
But that’s not exactly what’s happening, a new study suggests.
Rather than being attracted to light, researchers believe that artificial lights at night may actually scramble the innate navigation systems of flying insects, causing them to flutter in confusion around porch lights, streetlights and other artificial beacons .
“Insects have a navigation problem,” said Tyson Hedrick, a biologist at the University of North Carolina at Chapel Hill, who was not involved in the research. “They are used to using light as an indicator of which way is up.”
The insects don’t fly directly toward a light source, but “lean their backs toward the light,” said Sam Fabian, an entomologist at Imperial College London and co-author of the study. study published Tuesday in the journal Nature Communications.
This would make sense if the most powerful light source was in the sky. But in the presence of artificial lights, the result is confusion in the air, not attraction.
For the study, researchers attached tiny sensors to moths and dragonflies in a lab to film “motion capture” flight video – the same way filmmakers attach sensors to actors to track their movements.
They also used high-resolution cameras to film insects swirling around lights at a site in Costa Rica.
This allowed them to study in detail how dragonflies circle endlessly around light sources, positioning themselves with their backs to the beams. They also documented that some insects turn over – and often crash – in the presence of lights shining upward like spotlights.
Researchers found that insect flight was least disrupted by bright lights shining directly downward.
“For millions of years, insects oriented themselves by sensing that the sky is light and the ground dark” — until people invented artificial lights, said Avalon Owens, a Harvard entomologist who did not participate in the research.
___
The Associated Press Health and Science Department receives support from the Howard Hughes Medical Institute’s Science and Education Media Group. The AP is solely responsible for all content.