The use of biological control in turf has increased to avoid possible negative effects on humans. Entomopathogenic nematodes (EPNs) belonging to the families Steinernematidae and Heterorhabditidae have control potential against many economically important insect pests. In the present study, the efficacy of Heterorhabditis bacteriophora against a new pest on turf, Dorcadion pseudopreissi, was examined in the field. Cages (1 x 1 x 1 m) with female and male D. pseudopreissi were placed on two kinds of turf: Lolium perenne and Festuca arundinacea. After beetles had deposited eggs into the moist soil surface, the cages were removed and H. bacteriophora was applied at 0.5 million infective juveniles/m(2) to half the plots. Application of H. bacteriophora caused a statistically significant reduction in numbers of beetle larvae in L. perenne plots and a non-significant reduction in F. arundinacea plots. The area damaged by D. pseudopreissi was significantly reduced by nematode application in both turf species. The number of nematodes declined after application, but small numbers could still be detected after 6 months.