Insects|Human artificial light messes up orientation.
Known a sight on a dark August night: winged insects swarming around the lamplight. Entomologists also use this method when they want to get something to study. But why does it work?
The light from the lamp represents heaven to the insect, a researcher at the Florida Museum of Natural History points out by Yash Sondh with colleagues Nature Communications – in the science journal.
The team filmed insects flying through the stages of a lamp in a forest in Costa Rica with high-speed cameras. When you watch the videos in slow motion, it is revealed that when flying, the insects keep their backs towards the light source.
“When people see the phenomenon around their yard lights or a street lamp, it looks like the insects are flying straight towards the light, but that’s not the case,” says Sondhin in the research bulletin.
For insects gravity is not enough to reliably tell what is up and what is down. Therefore, they need the light of the sky to control their movement. Even the night sky helps to navigate.
Artificial light produced by man, however, is dim and misleads the squeamish. Insects trapped in the lamp exhaust themselves trying to take their flight from it. Sometimes they bump into the lamp.
Researchers first discovered the phenomenon in the laboratory with bedbugs and dragonflies.
“In one of the first tests, I let fly from my hand a large ladybug towards the UV lamp, and it immediately turned upside down,” says Sondhin.
In the end, even in nature, it turned out that the wings of all studied insect families turned their backs towards artificial light.
Published in Tiede magazine 9/2024.
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