Why is it that insects are attracted to artificial light?

Weekend outdoor barbecues with friends, family, and relatives are the perfect way to unwind and escape from work-related stress. Unfortunately, swarms of insects like moths, midges, and mosquitoes can disrupt the fun with their troublesome presence, especially during summer evenings.

It's rather peculiar that these insects are so drawn to artificial lights, which can be lethal to them. They may end up trapped under lampshades, be exposed to predators like cockroaches, bats, birds, and spiders,or get burned by the heat of the lamps or open flames. Avalon Owens, a Harvard University scholar, explains how insects prioritize the attraction to artificial light over essential activities like eating and mating.

However, could this attraction to artificial lights endanger insect populations? Studies suggest that artificial lights are contributing to a decline in insect populations globally. So why are insects so attracted to artificial lights? There are several theories, including the idea that moths may mistake the lights for the moon, which they use for orientation. Additionally, insects may be trying to escape to the light or find darkness. Optical illusions like "mach bands" might also play a role, making the edge of a lit area look darker than the surrounding darkness.

An outdated theory from 1965 suggested that lights might mimic mating pheromones, but this theory lacked evidence. However, it is possible that insects' older evolutionary responses are being hijacked, and they fly towards lights due to this. Owens explains that for most of evolutionary history, the night has been almost entirely dark, so this attraction to artificial lights is a recent phenomenon.

Testing specific hypotheses about insects in flight is challenging, but new technologies may provide better answers. For example, a recent preprint study on bioRxiv filmed moths, dragonflies, and other insects with high-speed cameras. Researchers noticed that moths and dragonflies kept their backs to the light as much as possible, suggesting that some insects fly towards the light to orient themselves. Insects may associate light with "up" and darkness with "down," making it difficult for them to use gravity to determine their position.

While this experiment may explain why insects stay close to lights, it doesn't explain how some insects detect lights over long distances or why some get stuck while others don't. Nonetheless, this research sheds light on the mysterious attraction of insects to artificial lights and could help us find ways to reduce their impact on insect populations.

Written by Chatsonic