A new species of steinernematid, Steinernema kushidai was recovered from a soil sample collected in Hamakita City, Shizuoka Prefecture, Japan. The nematobe showed a significant lethal effect on several species of scarabaeid grubs. Application of 1,000 infective juveniles (IJ) of the nematobe onto the soil in plastic cups where the 3rd instar larvae of the cupreous chafer were individually reared killed the larvae within a few days. In applications of the nematobes on soil in a sweet potato field, more than 100,000-200,000IJ/m² reduced the numbers of the sweet potatoes seriously injured by scarabaeid grubs. S.kushidai applied on a sweet potato field and on a nursery of the Japanese cypress persisted for at least 2 years. The nematode could be propagated in vitro on peptone or yeast extract-rich media.