The entomogenous nematodes Steinernema feltiae Filipjev ( = Neoaplectana carpocapsae Weiser), S. glaseri Steiner, and S. bibionis Bobien (Steinernematidae: Rhabditida) were evaluated as biological control agents against the banana root borer weevil Cosmopolites sordidus. In the grub stage this weevil bore tunnels in the corms of plantains thereby promoting infection and plant decay. In petri-dish trials the three species produced severe mortality at population densities of 4,000 and 40,000 nematodes. Similarly, in greenhouse tests, the three nematode species at rates of 400, 4,000, and 40,000 nematodes/4-month-old plants apparently reduced the number of tunnels produced by the grub. Grub mortality was 100% at nematode populations of 4,000 and 40,000 per plant.