Re: Why moths are attracted to light. http://www.straightdope.com/columns/read/1071/why-are-moths-attracted-to-bright-lights
Hsiao is incorrect when he says that moths avoid the bright light once they approach it. This is easily demonstrated by observing the annual gathering of billions of moths in the bright beacon atop the Luxor casino in Las Vegas. The beacon is filled with moths that are obviously not trying to avoid it. Rather, the moths appear to be mating. When the mating season is over the moths leave the beacon alone.
This makes a lot of sense, actually. How does a nocturnal creature find a mate? It is dark, after all, and mates are hard to see. Pheromones let you know that potential mates are nearby, but it can be difficult to pinpoint the exact location. The best chance at finding a mate would be to find a concentration of other insects. Thus, head to the brightest point in the area, whether it is a porch light, candle flame, luminous mushroom, or whatever.
It is possible that the males of some species of moths die shortly after mating (hardly an unknown phenomenon in the insect world) and that these account for many of the moths “killed” by the light source.
Hsiao’s mistake is in assuming that the moths are avoiding predators. However, most nocturnal predators do not need light to find moths. Bats, for example, use echolocation. If Hsiao sees moths staying a foot away from a light bulb, it is more likely that the moths are avoiding excessive heat. They get as close as they can stand it, but no closer.