Most people know that moths find lights irresistible. But what they may not realize is that the energy moths expend in this way can cost females the chance to attract a mate. What's more, it can interfere with locating prime spots to lay their eggs, thus giving larvae inadequate conditions to develop, according to Michael Collins, a lepidopterist at the Carnegie Museum. Some entomologists speculate that the proliferation of outdoor lights has contributed to the decline of numerous saturniid moth species in the northeastern United States. Visual orientation is just one sense disrupted by artificial light, though it probably isn't the only one, says Mere-dith West, an Indiana University professor specializing in avian development.
Lighting is a powerful stimulus on behavior.
If there's enough of it, it can make them act in ways they wouldn't normally. Adult female sea turtles will not emerge from the water to nest and lay eggs on beaches that are bathed in artificial light. Hormones regulate growth and immune functions. But they're not produced all the time. If they don't shut down, you overload the body.