Recent studies indicate that “cool” white lights, like those found in contemporary car headlights, pose a risk to moths by causing them to fly unpredictably.
Researchers from the University of Exeter conducted experiments where moths were subjected to brief flashes of light that mimicked car headlights, and then tracked their flight behavior.
The study revealed that the “cool” white LEDs used in modern vehicle headlights bewildered moths, significantly impacting their flying patterns.
Specifically, moths exposed to these lights were 80% more likely to fly in erratic patterns or head straight for the light, and they exhibited these unusual flight behaviors 25 times more than a control group that did not experience any light.
Moths serve vital roles as pollinators, pests, and food sources in ecosystems. In the UK, there are over 2,500 moth species, many of which are currently facing rapid population declines, resembling patterns observed globally.
Light pollution is a key factor contributing to their decline, with most research focusing on the impact of streetlights. However, headlights from vehicles create powerful light pulses that can reach deep into sparse rural areas and dark skies.
“Vehicle headlights are increasingly getting brighter and bluer,” stated Dr. Jolyon Troscianko from the Centre for Ecology and Conservation at Exeter’s Penryn Campus in Cornwall.
“Unlike humans, whose pupils can adjust to bright glare in less than a second, insects take much longer, sometimes up to tens of minutes, which makes them particularly vulnerable.
“Moths drawn towards car headlights risk collision fatalities, and erratic flying can waste energy, increasing their vulnerability to predators like bats.
“Since many moths are active only briefly at night, such disruptions can hinder their ability to feed and mate.”
The research team captured and examined 428 moths from 64 different species at the Penryn Campus. Each moth was subjected to one of the following light conditions for 10 seconds prior to their release:
- “Cool” (blue-shifted) white phosphor-coated LEDs.
- “Warm” (amber-shifted) white phosphor-coated LEDs.
- “Cool” RGB (Red-Green-Blue) LEDs, which produce light from three differently colored LEDs.
- “Warm” RGB LEDs.
- No light (control group).
Moths in the control group typically flew either upward or downward upon release. In contrast, those exposed to the cool phosphor-coated LEDs were more inclined to fly toward the light or engage in tight circles, a behavior rarely seen in moths when not influenced by artificial lighting.
“By simply adopting warmer-colored LEDs or alternative LED technologies, we can significantly lessen their impact on moths,” explained Madeleine Fabusova, who gathered the data while pursuing her MSci in Conservation Biology and Ecology at the University of Exeter.
“Our findings indicated that the harmful effects of cool phosphor-coated LEDs were greater than those of RGB LEDs, which produce an identical white appearance to human vision.
“The consistency of our results across various moth species was quite remarkable.
Reducing the blue spectrum in headlights could thus benefit moths, the flowers they pollinate, and the wildlife that depends on them.”
On the subject of the movement toward brighter, bluer headlights, Professor Kevin Gaston from the Environment and Sustainability Institute at the University of Exeter remarked: “There are no safety advantages for people from these blue lights compared to those containing more red and green hues — this trend seems to originate from car manufacturers.
“Car manufacturers, consumers, and policymakers can all contribute to implementing a relatively straightforward change to mitigate our impact on the environment.”
This study received funding from the Natural Environment Research Council.
The research paper, titled “Pulsed artificial light at night alters moth flight behaviour,” was published in the journal Biology Letters.
