We Stole the Dark
How artificial light at night is dismantling the insect world, one garden lamp at a time.
The moth on your windowpane is not confused. She is dying.
She has been circling the same light source for hours, unable to stop, unable to navigate away. What looks like a harmless, slightly melancholy insect tableau is actually a navigation system catastrophically overloaded.
Most people never learn this about insects. Subscribe if you want to be in the minority that does.
Moths evolved to use the angle of the moon for orientation, a behaviour called transverse orientation. Keep the light source at a fixed angle relative to your body and you travel in a straight line. It works perfectly, provided the light source is 384,000 kilometres away and effectively at infinity. Put a lamp post six metres in front of her and the algorithm breaks. She spirals inward. She exhausts herself. She dies, or if she survives the night, she is too depleted to mate, to lay eggs, to do the thing she was built for.
We have done this to the entire insect night shift.
Most people do not know that a significant proportion of pollination happens at night. Not by bees, who are resolutely daytime creatures, but by moths, beetles and other nocturnal insects visiting flowers specifically adapted for them. White flowers visible in low light. Blooms that open after dark and release their fragrance into the cool air. Evening primrose. White campion. Night-scented stock.
These plants evolved alongside their nocturnal pollinators over millions of years. The pollinators navigated by starlight and moonlight for most of that time. Then, in the span of roughly a century, we lit everything up.
Artificial light at night, which researchers now abbreviate to ALAN because the full phrase has to be said approximately four hundred times per paper, has been documented disrupting insect behaviour in ways that ripple through entire food webs. It suppresses the emergence of nocturnal insects. It desynchronises mating behaviour in species that rely on bioluminescence, including fireflies, whose light signals are simply drowned out. It alters the foraging patterns of bats, who hunt around light sources, creating ecological traps that concentrate prey in ways that unravel the natural balance below them.
The darkness is not empty.
It never was. It is a habitat. It has a food web, a set of relationships, a timing system that evolved over geological timescales. And we deleted it from most of our landscape without noticing, because we were not looking.
The light pollution map of the UK is almost entirely orange. The areas of genuine dark sky are small, concentrated in national parks and remote uplands. The rest of the country glows. Street lights designed for car headlight levels, burning through the night on roads that carry five vehicles an hour after midnight. Security lights that trigger for hedgehogs. Garden ornamental lighting sold as creating atmosphere. Illuminated advertising hoardings in retail parks, blazing through the small hours for nobody at all.
There is a particular sting in the fact that a lot of ecological light pollution comes from people who mean well. The beautifully lit garden, the warm amber glow from the kitchen spilling onto the patio, the fairy lights in the pergola. These are the aesthetics of comfort and care. They look nothing like destruction.
But consider what the garden looks like from the perspective of the moth. A landscape that was once navigable by ancient celestial cues is now so full of false signals that she cannot find a mate, cannot find the flowers she needs, cannot even rest in darkness to thermoregulate properly. And the flowers she might have visited are also deprived of their pollinators, quietly setting less seed, slowly declining, generation by generation.
The simplest and cheapest conservation action most households could take is to turn off outdoor lights after midnight, or switch to motion-activated, warm-spectrum, shielded fittings that direct light downward rather than into the sky and the hedgerows. The darkness returns within days. Moths return within weeks, if there are moths left in the landscape to return.
We did not ask the insects whether they wanted the night shift abolished.
The darkness was never ours to take. And it turns out the ecosystem was using it.
If this made you look at bees differently, you will probably enjoy what comes next. Subscribe to keep exploring.
Further reading:
Peer-reviewed references:
The impact of artificial light at night on nocturnal insects
https://www.sciencedirect.com/science/article/pii/S0006320719307797
Pollination by nocturnal Lepidoptera, and the effects of light pollution: a review
https://pmc.ncbi.nlm.nih.gov/articles/PMC4405039/
Nocturnal pollination: an overlooked ecosystem service vulnerable to environmental change https://pmc.ncbi.nlm.nih.gov/articles/PMC7326339/
Artificial light at night as a new threat to pollination
https://www.nature.com/articles/nature23288
Ecological consequences of artificial night lighting
https://onlinelibrary.wiley.com/doi/10.1111/brv.12036
Thanks for educating! I had absolutely no idea and now I’m so worried about those moths. I will definitely manage my night lights better. Poor beasts 💚
Brilliant read.