The longstanding belief that bright lights attract flying insects may not be entirely accurate, according to a recent study.
Researchers suggest that artificial nighttime lighting could interfere with insects’ natural navigation systems, leading them to fly erratically around sources of light such as porch lamps and streetlights.
“Insects face a navigational challenge,” explained Tyson Hedrick from the University of North Carolina, Chapel Hill, who was not involved in the study. “They rely on light cues to orient themselves.”
Contrary to popular belief, insects don’t fly directly towards light sources; instead, they angle their bodies towards the light, as noted by Sam Fabian from Imperial College London, a co-author of the study published in Nature Communications.
This behavior would make sense if the strongest light source were in the sky. However, in the presence of artificial lights, it leads to confusion in midair.
In the study, researchers attached tiny sensors to moths and dragonflies in a lab setting and filmed their flight using motion-capture technology. They also observed insects flying around lights in Costa Rica using high-resolution cameras.
These recordings revealed how dragonflies continuously circled light sources, positioning themselves with their backs to the light. Additionally, researchers observed insects flying upside down and often crashing when confronted with lights that shine directly upward, such as searchlights.
The study found that insects were least disrupted by bright lights that shine directly downward.