In caterpillars of species that habitually feed on the undersides of leaves, however, this counter-shading is reversed. Many camouflaged caterpillars are barred or blotched like the clothing of a soldier or hunter. Other caterpillars disguise themselves as a defense. For example, bird-dropping mimicry is fairly common. In some swallowtail species the caterpillars are white with green blotches and have the slimy look of fresh bird feces.
Some caterpillars even change their disguise as they molt and grow.
Others are stick mimics, such as the inchworms that clasp twigs with their posteriors and hang away at an angle like small side branches. Experiments with insect-eating birds show that they usually do not detect immobile stick mimics but eat them instantly if they move. Another caterpillar defense is snake mimicry. Several kinds of moth caterpillars respond to disturbance by inflating the front of their body into a snake-like head complete with large imitation snake eyes. Thus transformed, they twitch from side to side in a startling manner.