In. the spring of I97I, Neoaplectana bibionis Bovien was re-isolated from larvae and pupae of Bibio hortulanus L. and other bibionids from 3 localities in Denmark. Third stage infective larvae were recovered and used to initiate laboratory cultures. When nematodes were injected into the mouth of the greater wax moth larvae, Galleria mellonella L., they quickly penetrated into the hemocoel of the living insects and brought about their death. Successive nematode generations also occurred on artificial media used for rearing Neoaplectana carpocapsae Weiser. A specific rod-shaped bacterium was isolated from the intestine of infective stage larvae and probably has the same relationship to the nematode as N. carpocapsae has to its symbiotic bacterium, Achromobacter nematophilus. This nematode may make an excellent candidate for biological control programs involving soil insects.