Naturalists have noticed for at least a century that insects have a way of mimicking each other. Butterflies of two species not closely related often show similar patterns of bright colors. Generations of entomologists have suspected that nature thus protects a butterfly that birds consider delicious by enabling it to resemble one that is distasteful to birdsbut this theory has been widely debated and rarely tested experimentally. In Natural History, Biologists Lincoln P. and Jane Van Zandt Brower of Amherst College settle at least part of the argument about the survival value of nature's insect masquerade.
Instead of working with butterflies, the...