This text provides a tour through the extensive literature on one of the largest families of insects, the family of the leaf beetles, or the chrysomelidae. It is anintroduction to their biology and also, given their phytophagy, to their agricultural importance. Many chrysomelids are crop pests. An account of chrysomelid food has therefore been included, and interesting deviations from their phytophagy have been described. Also covered are the various defence mechanisms exhibited by leaf beetles against parasites and predators.