The search for natural enemies of the South American tree Solanum mauritianum Scop., a major environmental weed in the high-rainfall regions of South Africa, created the opportunity to observe and study several leaf-feeding beetles from the genus Platyphora Gistel. Data on the biology and host range of three species from southern Brazil, Platyphora biforis (Germar), Platyphora conviva (Stål) and Platyphora nigronotata (Stål), and one from northeastern Argentina, Platyphora paraguana (Jacoby), were collected during their evaluation as potential biological control agents. All four species displayed similar, highly specialized biologies in the field, including viviparity, monophagy and sensitivity to host plant quality and microhabitat. Despite this, considerably broader host ranges were observed in captivity, including both cultivated and native South African species of Solanum L. Certain of these non-target plants were suitable hosts for the beetles, because there were no consistent differences in survival and duration of development of the immature stages on these compared with S. mauritianum. However, evidence from the literature that species of Platyphora associated with Solanaceae have very narrow host ranges, and that none are known to attack cultivated Solanum species in South America, strongly suggests that the laboratory tests do not reflect the true host ranges of these beetles. Despite this possibility, none of these beetles were considered suitable for release in South Africa and further studies were terminated.