The fact that entomopathogenic nematodes of the genera Heterorhabditis and Stemernema are normally found in mutuahstic association with the bacteria Photorhabdus spp. and Xenorhabdus spp , respectively, has long been universally accepted However, the extent and nature of their interaction with bacteria other than these, under natural conditions, is less well known. There have been a number of reports of other bacteria being isolated from entomopathogenic nematodes, particularly from Stemernema spp. (reviewed by Boemare et al, 1998a). Jackson et al (1995) reported the occurrence oí Providencia rettgeri with a number of strains of Heterorhabditis spp. originating from different geographical regions. Boemare et al (1998b) point out that écologiste will tend to harvest nematodes resulting from "successful" parasitisms, i e. those where the cadaver is not more rapidly putrefied by the presence of co-associated bacteria other that the natural symbiont. With this in mind it is conceivable that we may under-estimate the frequency of association of these nematodes with other bacteria.