To Protect Pollinators, We Need To Fight Light Pollution

By Kaitlin Haase

When we think of how to protect pollinators, it’s easy to focus on the ones we see: species of bees, butterflies, and other bugs that are, just like us, active during the day. But that’s only half of the story. Nighttime pollinators are not only widespread and important, but are facing a serious threat that daytime animals don’t have to worry about: artificial lights.

Many nighttime insects are incredible pollinators

Around 60% of insects are active at dusk, night, and dawn–and many of them are also pollinators! This “night shift” includes many nocturnal species of moths, beetles, flies, and bees. That’s right, there are some bee species evolved to visit flowers after dark! One group of bees that are active before the sun rises are squash bees, which can be found pollinating squash blossoms in the dark morning hours. The most important nighttime pollinators, moths, have been reported to be responsible for 50% of apple pollination in Arkansas orchards, meaning they can do as much work as all the different daytime pollinators put together! However, if we don’t act soon, we risk losing more and more of these incredible animals.

A hairy brown and white moth with prominent antennae, outstretched wings, and a long proboscis drinks nectar in flight from a pink thistle flower. The background is completely black, appearing to be at night.
Moths, like this white-lined sphinx moth (Hyles lineata), are important pollinators of wild and cultivated plants. Many moths are night flying and their ability to survive and pollinate flowers is hindered by artificial light at night. (Photo: Stephanie McKnight / Xerces Society)


Artificial light at night puts pollinators in peril

For millions of years, plants and animals evolved alongside a natural cycle of dark nights and bright days. But within just the last 200 years, artificial lights at night (ALAN) have radically changed that cycle, harming the many species that evolved to expect and rely on the night actually being dark.

Just like ancient humans did, many invertebrates use the daily setting and rising of the sun, phases of the moon, star light, and seasonal changes in daylength to learn about the world and make vital decisions. These include when and how they migrate, forage, mate, emerge, and move around. Many insects use the faint glow of the moon or stars to tell which way is up when flying in complete darkness. And some, like nocturnal dung beetles, use the position of the Milky Way galaxy overhead to be able to move in perfectly straight lines as they roll their dung balls away from the larger pile. Of course, the poster child of nocturnal insects, firefly beetles, need darkness as backdrop to their flashing courtship displays and to successfully communicate with each other.

But just as water pollution makes taking a drink dangerous, light pollution by ALAN puts nocturnal bugs at risk when they try to follow their instincts. Light pollution comes in two types, sky glow and point sources of light. 

Sky glow, caused by all of the thousands and thousands of lights shining up towards the sky, makes the moon and stars much harder to see. Like how loud speakers at a concert can make having a conversation with someone nearby almost impossible, sky glow prevents nocturnal bugs from getting the information they need to navigate and time their life cycles.

Looking from a wetland and natural area in a park out into the surrounding streets. Many of the houses have unnecessary lighting in their backyards that throw light far into the wetlands. Instead of darkness, the sky behind the lights is a bright grey, blocking out all but the brightest stars, which are just barely visible.
Each bright artificial light is dangerous for insects nearby, and added together, they create a sky glow that completely hides all but the brightest stars. (Photo: Xerces Society)

Point sources of light such as a single lamp post or porch light can attract and disorient insects. While flying, nocturnal insects try to keep the bright moon or starlight above them to keep from flying into the ground. But with a lamp post, this behavior causes them to fly endlessly in circles around the light, where they may perish from exhaustion or are easily caught by predators. Moths and many adult aquatic insects are especially at risk. These lights also make it harder for nocturnal pollinators to actually find and pollinate flowers!

While already very difficult to find, natural darkness at night is becoming even more rare in most landscapes across the globe. In the United States, only 20% of people live somewhere where they can see the Milky Way for themselves, because the light from our galaxy is completely drowned out by light pollution. With the omnipresence of light pollution and its effects on the majority of insect life, we need to address this threat in our conservation efforts.  

We have the power to protect wildlife from light pollution

While we might feel more comfortable in the light of day, darkness is good for us and the planet. Excessive light at night wastes energy and money. Human circadian rhythms, or the internal “clock” our bodies use, are disrupted by ALAN, impacting our ability to sleep and increasing stress. While many aspects of human cultures, curiosity, and technology came from us gazing up at the moon, stars, and constellations, that source of inspiration is no longer available to every, or even most, people. 

A time-lapse photo of a field and night sky. Dozens of trails of green flashes show fireflies moving around against the dark ground and trees, and the many swirls of lights in the sky show stars moving while the photo was taken.
Working together for dark nights means more people will be able to see experience fireflies and starry skies in person, instead of only through photos like this time-lapse. (Photo: Mike Lewinski CC-BY)

With all that we know about the harm of light pollution, controlling artificial lights at night is a critical step individuals, businesses, municipalities, and others can take to conserve pollinators and other wildlife. You won’t be alone. Across the world wildlife biologists, amateur astronomers, tourism and recreation professionals, artists, land managers, astrophysicists, and others are working together through organizations like Dark Sky International to make the night darker. 

You are an important part of protecting our nocturnal invertebrates and improving views of the night sky. With DarkSky International’s resources, you can work with your community to advocate for responsible outdoor lighting in public spaces. And at home, you can make some easy changes to help your local ecosystem:

  • Use outdoor lighting only where and when it is actually needed. Turn off any lights that don’t have a clear purpose.
  • Use motion-detectors and/or automatic timers so lights only turn on when they are most needed.
  • Use light covers or shields so that light only shines down to the ground, instead of outward in all directions.
  • Keep landscape lighting low to the ground, and away from white or reflective surfaces.
  • If lighting is necessary, swap out lights for less bright and warmer (yellow or red) bulbs, or cover existing bulbs with a filter that does the same.
  • Close your curtains at night to keep your indoor lights, well, indoors.

Learn more about light pollution and its effects on insects


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