Last week at one of the AMC huts, I was tucked away in my bed unable to sleep. Careful not to disturb my (loudly!) snoring neighbors, I turned on my headlamp to read. After a minute, I found myself bombarded with the fluttering of fuzzy little wings. I resigned myself to turning off my headlamp to avoid this nuisance, but also found myself grateful to have a sense of direction better than a moth.
Enter man made light. Lamps and campfires create a light brighter than any celestial body. Moths, confusing this man-made luminosity for the moon try navigate their way through the night by maintaining an angular relationship to these brighter objects. Unfortunately, these objects are too close to allow moths to maintain a straight line of flight. Instead, the moths spiral in towards the light, fluttering in heat and confusion.
So really, it is just a lesson in simple geometry and evolution has conserved this behavior for a very good reason. But if your brain can’t tell the difference between the moon and a head lamp, then the situation becomes a bit more complicated. As annoying as those moths may be, I have a greater appreciation for the moon, my headlamp, and the ability to tell them apart.