Two genera of entomopathogenic nematodes, Heterorhabditis and Steinernema, are mutualistically associated with their symbiotic bacteria. This study reports an identification of the symbiotic bacteria of H. megidis collected in Andong, Korea. The isolated bacteria emitted bioluminescence and showed red color on MacConkey agar medium. Fatty acid composition and carbon utility were analyzed by two microbial identification systems and showed high similarity with Photorhabdus temperata subsp. temperata. This identification was further supported by 16S rDNA sequence with 99.5% identity to that of P. temperata subsp. temperata. The bacteria had potent pathogenicity against the fifth instar larvae of Galleria mellonella and Spodoptera exigua.