Distribution of Japanese beetle,Popillia japonicaNewman, grubs and dispersal of an entomopathogenic nematode,Heterorhabditis bacteriophoraPoinar ‘Oswego’ strain (an isolate from New York state), were examined for 5 wk within soil-filled flats containing grass. Japanese beetle grubs uniformly dispersed to all sections of the flats not infested withH. bacteriophora‘Oswego’ strain. In flats infested withH. bacteriophora‘Oswego’ strain, however, greater proportions of Japanese beetle grubs were recovered in sections near the nematode release site or center sections of the flats.H. bacteriophora‘Oswego’ strain dispersed to all sections of the flats but dispersed more rapidly within the flats infested with Japanese beetle grubs than in flats not infested with Japanese beetle grubs.