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Schistocerca gregaria exhibits density-dependent body color polyphenism. Nymphs occurring at low population densities show green brown polyphenism. They show phase polyphenism and develop black patterns at high population densities. Recent studies suggest a third type of polyphensim, that is, homochromy, a response to background color. Laboratory experiments that considered homochromy suggest that humidity is not directly involved in green brown polyphenism and that odor from other individuals does not induce black patterns. Black patterns can be induced in isolated nymphs by video images of locusts and tadpoles. Juvenile hormone and [His(7)]-corazonin control body color in locusts. The gene encoding the latter has been identified for S. gregaria and Locusta migratoria, and its key role in controlling black patterning has been demonstrated.