Why Moths Fly to Light — How Artificial Light Tricks Insects
In short: The moth at your porch light is not drawn to the light. It never even steers toward it. A 2024 study using motion-capture cameras overturned a century of textbook explanation: artificial light hijacks the reflex insects use to tell up from down — the dorsal-light response — and turns a point of light into a cage with no walls. The Korean version of this story is already on the blog: 나방은 왜 빛에 끌릴까 — 인공 빛이 곤충을 속이는 이유 . The Moon-Compass Theory Ruled the Textbooks for a Century The beloved old explanation was elegant. A moth, the theory goes, navigates by holding a fixed angle to the distant moon. Moonlight arrives in effectively parallel rays, so keeping that angle constant means flying straight. But bring the light close — a candle, a bulb — and the geometry breaks: a nearby light radiates in every direction, the angle changes with every inch of flight, and constant correction curls the path into a spiral ending at the flame. It was intuitive, it was teachable, and it...