Moths are evolving to deal with city light pollution

April 15, 2016, 6 a.m.
An ermine moth on a fern.
Photo: Damian Money/Shutterstock

Of the many species negatively affected by the light pollution of cities, moths are right up at the top of the list. However, the tiny insects living in urban areas might just be evolving strategies to deal with the excess light and the trickery light plays on their navigation skills.

Researchers gathered a little over 1,000 moths while they were still larvae. Some were from areas with dark skies and some were from areas with light pollution. The larvae were raised in a "common garden setting" and once they were mature, the researchers tested their flight-to-light preferences.

"Moths from urban populations had a significant reduction in the flight-to-light behaviour compared with pristine populations. The reduced attraction to light sources of ‘city moths' may directly increase these individuals' survival and reproduction," write the researchers in the study, which was published in the Royal Society journal Biology Letters.

It shows that generations of urban moths dying at porch lights have made an evolutionary difference. However, there's a significant downside to this that affects other species reliant on moths.

According to Science magazine, "To avoid the lights, the moths are likely flying less, say the scientists, so they aren’t pollinating as many flowers or feeding as many spiders and bats."

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