Kids: Like a moth to a flame
Photo: Flickr user betenoir
You might have noticed moths gathered around lights or candles at night and wondered, what’s the big attraction?
Moths aren’t so much attracted to flame as they are disoriented by it. Like many flying insects, moths are able to find their way partly by using light as a compass. When the source of light is the sun or moon, that light source is very distant, and the incoming light rays that strike the insect arrive just about parallel to each other. So moths – and many other flying insects – have evolved to expect to receive light at a fixed part of the eye. As long as the moth flies more or less in a straight line, this visual pattern remains unchanged.
Now consider what happens when the light source is a nearby candle. Then the angle at which the light strikes the moth’s eye quickly changes while the moth holds to a straight-line course. The moth tries to maintain a constant angle to the source – and as it does so, it spirals in toward the light. So the moth seems “attracted” to the light – so much so that it may end up drawn into the flame.
