Field studies of predators on Aulacaspis tegalensis (Zhnt.) and laboratory breeding experiments, supplemented by taxonomic studies, showed that Chilocorus discoideus Crotch and C. bilineata Korsch. are junior synonyms of C. schioedtei Muls. and that two other forms, originally described as ‘aberrations’, may also belong to this species. Similarly, C. erythrocephalus Muls. and C. solitus Weise are junior synonyms of C. distigma (Klug). C. rufoplagiatus sp. n., allied to C. distigma, is described from the shores of Lake Victoria, and the Oriental species C. nigritus (F.) is recorded from the African mainland for the first time. C. distigma is found in the savanna and steppe areas of Africa and C. schioedtei in the forest and adjoining zones. Comparative studies suggest that, although C. schioedtei has a higher fecundity, it is not displaced by C. distigma as, unlike the latter, it is unable to breed under hot dry conditions. Comparison of host records for these two species show that C. distigma is not restricted to feeding on Diaspididae, as is C. schioedtei, but that otherwise the range of hosts and associated plants is similar for both species. The potential of these species and C. nigritus for use in biological control is discussed and it is suggested that C. schioedtei is only suitable for trial in tropical areas without a dry season, but that C. distigma and C. nigritus may be useful under a wider range of conditions.