New beetle vectors of southern bean mosaic virus and cowpea mottle virus were identified. Laboratory-reared adult Ootheca mutabilis Sahlb. (Chrysomelidae) efficiently transmitted both SBMV and CMeV to cowpea (Vigna unguiculata (L.) Walp.). O. mutabilis retained and transmitted SBMV and CMeV for 13 and 5 days respectively, following 24 h acquisition feeds. A second chrysomelid, Medythia quaterna Fairmaire, also transmitted CMeV to cowpea, but with less efficiency than O. mutabilis; this species also transmitted CMeV from cowpea to bambarra groundnut, Voandzeia subterranea (L.) Thou. Serological indexing was used to monitor vector transmission; none of the unexposed control seedlings was infected.