Scientists say light pollution may be contributing to “worrying” declines in insects seen in recent decades.
In a UK study, artificial street lights were found to disrupt the behaviour of nocturnal moths, reducing caterpillars numbers by half.
Modern LED streetlights appeared to have the biggest impact.
There is growing evidence that insect populations are shrinking due to the likes of climate change, habitat loss and pesticides.
Factors are complex and varied, including the steady loss of forests, heathlands, meadows and marshes, overuse of pesticides, climate change and pollution of rivers and lakes.
The use of artificial lights at night-time has been proposed as another driver of insect decline, although the scale remains unclear.
The researchers say their study, published in Science Advances, is the strongest evidence yet that light pollution can have detrimental impacts on local insect populations, with consequences for the birds and other wildlife that rely on caterpillars for food.
The researchers think street lights may deter nocturnal moths from laying their eggs or put the insects at risk of being spotted and consumed by predators such as bats.
In turn, caterpillars that are born under streetlights, particularly LEDs, alter their feeding habits.
But there are practical solutions that don’t compromise public safety, they say, including dimming streetlights in the early hours, fitting motion sensors or using colour filters to cut out the most harmful wavelengths.
In the study, experts from Butterfly Conservation, Newcastle University and the UK Centre for Ecology & Hydrology surveyed caterpillars on stretches of grassland and hedgerows at the sides of roads in southern England.
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