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Sesbania punicea (Cav.) Benth., a South American leguminous shrub or small tree, has recently become a weed, principally of river banks and of wetlands, throughout South Africa. Three weevil species have been introduced for its biological control: a florivorous apionid, Trichapion lativentre (Bèguin-Billecocq), that was inadvertently introduced in the 1970s, and two curculionids that were first released in 1984, a seed-feeder, Rhyssomatus marginatus Fahraeus, and a stem borer, Neodipiogrammus quadrivittatus (Olivier). The reproductive potential of S. punicea has been markedly reduced throughout South Africa by T. lativentre and, to a lesser extent, by R. marginatus. In the vicinity of release sites, many large S. punicea plants have been killed by N. quadrivittatus and the density of at least one infestation has been reduced to acceptable levels within 4 years. A critical assessment of this biocontrol programme is presented.