Contending with mosquitos on a summer evening, or flies at an afternoon cook-out, you might briefly imagine the world could do with fewer bugs. But insects are fundamental to life on Earth. They’re food for birds, reptiles and mammals. And they provide our species with essential “ecosystem services” – notably pollination, without which plants, including the ones we eat, can’t reproduce.
And insects are in serious trouble. Up to 40% of insect species could become extinct in the coming decades. Some causes of this “insect apocalypse” are predictable: climate change, habitat destruction, pesticides. But there’s another profound human-driven threat: light pollution. West Texas is the site of important research into this phenomenon.
Dr. Brett Seymoure, a professor at the University of Texas-El Paso, studies how light pollution impacts insects, and how to mitigate those impacts.
“Without ecosystem services, we do not have a functional planet and we're screwed,” Seymoure said. “So, sure, you want to go look at some stars. That's great. I mean, I do too. But at the end of the day, we are talking about an existential crisis with light pollution.”
We’ve all seen a moth lingering at a porch light. It’s like a deer in the headlights, Seymoure said, but for the entire night. It’s easy prey. And it’s not doing “moth stuff” – like feeding, pollinating and mating.
But light-pollution impacts are far more sweeping. Nocturnal insects have evolved to navigate by moonlight and starlight. They have night-vision capabilities we can’t imagine. Local tobacco hornworm moths can see color in conditions 10 million times dimmer than we require. Dung beetles roll their dung balls in straight lines to attract mates; they’re known to use the Milky Way as their guide. Artificial light affects insect migrations, and even how juvenile insects develop.
“Light is super important,” Seymoure said. “It's more important than water. If you wanted to mess with an ecosystem and not kill the ecosystem immediately, just change the lighting.”
Dark-skies advocates have assumptions about how to lessen these effects: shielding lights, so light is directed only to where it’s needed; using red rather than white or blue lights; placing lights on timers or motion detectors. Seymoure and his UTEP students are testing these assumptions. They’re working in El Paso, and at UTEP’s Indio Mountains Research Station. The remote property south of Van Horn provides pristine dark skies.
Shielding lights, they’ve found, is highly effective – an unshielded light attracts eight times more insects than a shielded one. Seymoure is less enthusiastic about red lights – they attract fewer insects, but can damage the plants on which insects rely, and they’re inconvenient for people. The researchers are also quantifying the significant benefits of using motion-detector lights.
“Whatever light bulb you have, assuming it's an LED because they're way more energy efficient, just put a shield on it,” Seymoure said. “And, for the love of God, don't have it on when you're not out there. Just turn it off – you're going to save money. Those are the two messages.”
One of Seymoure’s students is exploring how El Paso’s urban sky glow affects insects’ ability to navigate in the night.
Seymoure worked for years with the National Park Service, and its Natural Sounds and Night Skies Division. Trump Administration cuts have essentially brought the division’s work to a halt, Seymoure said. But Seymoure is part of a wave of young researchers studying light pollution and wildlife, and he’s optimistic about the future of the science.
“A lot of these really interesting questions and really important questions just have not been experimentally tested yet,” he said, “but they will be. We do have a lot of young people now that are starting to get into these professorships, and we should have a lot of cool answers very soon.”
Those answers could help avert the insect apocalypse.
This story was made possible by generous donations from supporters like you. Please consider showing your support with a contribution today.
