Insects Turn Their Backs on Artificial Lights When They Are Positioned Up [Study]

(Photo: Wikimedia Commons/Nevit Dilmen (talk))
Insects Turn Their Backs on Artificial Lights When They Are Positioned Up [Study]

Insects are seemingly attracted to light but get burned when flying too close to it. There have been various speculations about why they are drawn to light, but a new study suggests a further explanation.

Insects Fly, Flip Themselves Upside Down

When Yash Sondhi was a high school student, he visited a remote wildlife reserve in India with his parents. Sondhi saw thousands of moths and other insects of all hues and forms approach a brilliant light placed up in the darkness of the night there.

Nobody's responses were satisfactory. Perhaps insects' light-sensitive eyes become blind. Perhaps insects use the moon as a navigational aid and artificial light throws off their plan. Maybe it's a component of an "escape" strategy, where light signifies openings in the foliage that an insect would seek to avoid a predator.

As a PhD candidate, he continued to explore moth eyesight. One day, at a scientific conference, he came across a report by Imperial College London insect flying researcher Sam Fabian.

He points out that when a flying insect veers this way or that, it frequently experiences full-body accelerations that could be up to five times greater than the acceleration brought on by gravity. According to Fabian, this makes distinguishing between up and down difficult. For an insect, however, tilting its abdomen to face the bright sky is a simple and rapid way to get back on course.

"It's extremely smart because it's very finely tuned and it works beautifully until somebody invents the lamp or the light bulb," Fabian said, "and then it's suddenly not such a good idea anymore."

According to the new research, any insect that tries to maintain its back angled towards the brightness will begin to fly in erratic patterns similar to those seen around any porch light when the brightest light emanates from an artificial light.

Lights that point down from above can be easier for insects to see. However, when the light is pointed upwards, they struggle considerably more because the sky appears on the ground, according to Avalon Owens, a Harvard University entomologist who researches how artificial light affects insects but was not involved in this study.

The study appears to have one important lesson for everyone who cares about insects: you shouldn't point lights up at the sky.

(Photo: Wikimedia Commons/Nevit Dilmen (talk))
Insects Turn Their Backs on Artificial Lights When They Are Positioned Up [Study]

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Insects Are Not Attracted To Light

Scientists have discovered that insects are not attracted to light despite being so keen on it. According to one study, they appear to alter their route toward a light if it happens to pass by because of an odd innate biological response rather than flying toward lights because they are attracted to them.

Scientists have found that most flying insects display some form of dorsal-light-response behavior, or DLR, which involves maintaining their dorsal (top) side facing the brightest area of the visual field.

The insects can maintain perfect flying attitude and control because this DLR helps them discern which direction is up since the moon or sun is usually located almost directly above them.