We really need to give insects more credit. They pollinate the shit out of our flowers. They break down dead things. They even help us understand local water quality. And how do we thank them? By killing them with pesticides, habitat destruction, and climate change. Now scientists are sounding the alarm on nighttime light pollution.
In a paper published in Biological Conservation last week, a team of entomologists reviewed some 200 studies and research papers to get a sense of how light pollution is contributing to the so-called insect apocalypse researchers flagged in April. Though that paper discussed habitat loss and agriculture as serious threats to insects—noting that more than 40 per cent of insect species face potential extinction over the next few decades (results that also saw some pushback)—the landmark study made no mention of light pollution.
That’s exactly why this team of entomologists brought their insect review all about light pollution to the same journal that published that April study.
“It’s frustrating,” author Brett Seymoure, a postdoctoral fellow at the Living Earth Collaborative at St. Louis’ Washington University, told Earther. “We’re saying, look, light pollution is also a huge driver, especially with nocturnal insects.”
The way he sees it, light pollution is the easiest threat to remove. It might not be the worst threat for all insect species, but it’s definitely among the top threats for many, especially those in more developed parts of the world like Europe and North America where lights are seemingly everywhere. Reducing or eliminating light pollution doesn’t take much.
“With some small changes and some upgrades to lighting, we can still have light at night and drastically reduce light resulting in insect declines ,” Seymoure said.
Among the quick fixes, Seymoure said some light timers, covers to minimise light pollution, and bulbs that don’t mimic daytime would go a long way to reducing the negative impact of night lights on bugs. Beyond that, we need to reduce the amount of light people emit, in general, and be careful with the light we do use at night.
Here’s the thing about lights and bugs. First off, many insects are attracted to lights and die instantly because of the heat generated by incandescent bulbs. Scientists still aren’t sure why bugs exhibit this behaviour toward lights, but they think it’s because many insects rely on celestial cues—like the position of the moon or Milky Way—for navigation. When you’re a tiny insect, you might confuse a stupid streetlight for the moon. Or you might struggle to find the Milky Way due to all the light pollution obscuring it. When insects go and spend a night with a light, they have a 30 per cent chance of being dead by the morning due to exhaustion or predators, the paper notes.
So there’s that, but the paper also shows that lights do more than lure bugs to their immediate death. They affect how species move, forage for food, reproduce, how hide from predators, and even how they grow.
Certain insects only forage when it’s sufficiently dark. Night lights mean they may be waiting a long time for that moment to come, and may not consume enough food to grow nice and healthy. Other insects such as fireflies rely on lights on their tiny bodies to woo a mate. How will that mate see them light up if artificial light is, well, everywhere?
While researchers understand the impact light is having on some insects, there’s still a lot left to be studied on how to best minimise night light impacts. Is there an ideal wavelength for lights that would reduce their damage to bugs, for instance? And how much does light pollution exacerbate threats that already exist due to climate change and habitat fragmentation? The impact on of nighttime lights on specific species is also an area researchers need to dig into since not all bugs are impacted the same way.
Seymoure plans to take a deep dive into light pollution’s effects on butterflies. He thinks that might help spur public interest in the topic. After all, if the people don’t demand change then it may never come. And if we don’t act quickly to save the bugs, we may be next on the extinction list.
“If we lose these insects, you’re also gone,” Seymoure said. “It’s over.”