Have you ever come home from a long day to find your front door swarmed by flying insects? Or more accurately, your front door’s light? Turns out, that’s more than a minor inconvenience. Light pollution is contributing to worldwide insect decline and that’s actually a huge problem. Insects may seem pesky. They bite and sting us, flutter and scuttle into our houses, swarm around our faces and eat our crops. But actually, of all the insects in the world, only 1% of them are pests responsible for any real damage! And almost all insects play really important roles in our world. For instance, many are pollinators, so they keep ecosystems running by perpetuating plant populations. They play a role in energy cycling as they aid in decomposition and disposal of waste. And they’re also food for many other organisms, like small rodents, amphibians, birds and bats— all of which have important jobs to do in the world’s food and energy webs. I say all of this to give perspective to this next fact: a recent study, the most comprehensive of its kind, estimates that 40% of the world’s insect species may become extinct within the next few decades. The groups of insects that are most at risk are Lepidoptera, which includes moths and butterflies, Hymenoptera, which includes bees and ants, and—as a separate category—dung beetles. But the problem, like most, is complex. A changing climate messes with things like insect reproduction and migration, both of which are highly sensitive to changing patterns in seasonal temperatures and precipitation. Habitat loss and fragmentation actually pose one of the biggest threats to insect populations, as wild land across the globe is rapidly converted for human activities like intensive agriculture. The use of chemical pesticides and other kinds of pollutants is certainly another big contributor to the very real threat facing not only bugs, but us as well. ‘Cause I don’t think I can emphasize enough just how important bugs are to our world. We need these insects, especially Hymenoptera to make our food possible. You may have seen that photo showing what a grocery store would look like without bees? The shelves are almost entirely empty. Now, picture that kind of diversity loss radiating across entire ecosystems, not just the grocery stores where we shop for food. Losing 40% of the world’s insects would make up the majority of the species loss in the sixth extinction. That’s the major extinction event we’re experiencing right now in the present Anthropocene epoch. This event is largely human-driven and will take radical efforts on the part of humans to make it stop. So what can we do? One seemingly simple thing? Turn our lights off. Some bugs move toward light, or are what’s called positively phototactic, and we have a couple of ideas about why that is. It could be that light messes with their internal navigation systems. With the flood of artificial light they can’t navigate by natural sources of light like the moon, so they end up getting all turned around and just fly themselves to death. And some artificial lights may even give off low levels of UV light, which insects may mistake for UV signatures from flowers. Some lights give off infrared radiation which can seem like female moth pheromones, which register to male moths in the infrared. In these ways, the light messes with their navigation and may also make it more difficult for insects to find mates, by disrupting their natural patterns. Fireflies, for instance, can’t see each other glow if the whole area is flooded with light! And light also makes it easier to see those bugs, and so they are more susceptible to getting eaten by predators. So even though we’re not sure exactly why bugs flock to flame, we are sure that artificial light is a driver of insect decline. And no—artificial light at night is not driving global decimation of insect species as much as say, habitat loss. But addressing our light usage is something relatively simple we can do to address this issue, and pretty much immediately. Because here’s the kicker. 41% of global insect species have already experienced huge population declines in the past decade. So as this insect species loss continues and accelerates—it will be devastating. Not only for us, but for the whole world’s wider ecosystems. And it’s going to take large-scale change in our land management and our use of pesticides to stop that cataclysmic decline before it’s too late… but changing our light habits is maybe one place to start. If you want to know even more about surprising ecosystem dynamics, check out this video on fungi over here and subscribe to Seeker for all of your ecological updates. Leave a comment down below, and as always, thanks so much for watching. I’ll see you next time.