Oral toxicities of 5 Photorhabdus temperata ssp. temperata (Ptt) strains collected in different regions of Korea were determined against the larvae of Plodia interpunctella, Galleria mellonella, Lucilia caesar, Culex pipiens pallens and Paratlanticus ussuriensis. When a diet or water containing culture media of 5 different Ptt strains were ingested to immature insects, mortalities of the first instar larvae of G. mellonella, L. caesar, P. ussuriensis and young nymphs of C. pipiens pallens were rapidly increased and 100% within 3-5 days after treatments. However, mortality of P. interpunctella neonate larvae was slightly slower and 94.4-100% within 7 days after treatments. As controls, a diet containing either water, the medium without culturing bacteria, or E. coli culture medium did not effective on their mortalities. As another control group, the culture medium of P. temperata ssp. laumondii (KACC) were variously effective to mortalities of 4 species, namely, 100, 45.3, 2.8 and 0% to Galleria, Lucilia, Plodia and Culex, respectively. Culture media of Ptt strains inhibited developmental late of late larvae of P. interpunctella. Our results suggest that the oral administration of the culture medium of Ptt symbiotic bacteria was highly effective to control various immature insects.