Ricania simulans (Hemiptera: Ricaniidae) is a serious pest present in several countries throughout the world including Turkey, China, Japan and Taiwan. This study investigated the bacterial flora of R. simulans, and tested them for the insecticidal activity in order to find an effective and safe biocontrol agent for this pest. Based on conventional and modern tests, twelve bacterial isolates were identified from the microbial flora of R. simulans; Pseudomonas oleovorans (Rs1), Pseudomonas parafulva (Rs2, Rs3 and Rs5), Pseudomonas sp. (Rs4, Rs7, Rs9), Pantoea sp. (Rs6), Microbacterium paraoxydans (Rs8), Bacillus safensis (Rs10), Chryseobacterium indoltheticum (Rs11) and Bacillus thuringiensis (Rs12). The insecticidal activities of the bacterial isolates were determined on nymphs at five different concentrations (1.8 X 109 bacteria/mL, 1.8 X 108 bacteria/mL, 1.8 X 107 bacteria/mL, 1.8 X 106 bacteria/mL, 1.8 X 105 bacteria/mL), and on adults with different three concentrations (1.8 X 109 bacteria/mL, 1.8 X 108 bacteria/mL, 1.8 X 107 bacteria/mL) for 10 days. The highest insecticidal activity was determined with Rs4 on nymphal stage of R. simulans by 82% killing rate within 10 days. Bacillus thuringiensis tenebrionis (Xd3), Bacillus thuringiensis kurstaki (MnD), Bacillus thuringiensis kurstaki (BnBt), and Serratia marcescens (BnSm), which were proven effective biocontrol agents our previous studies, were also tested against this pest. BnSm showed the highest insecticidal activity with 93% killing on adult and nymph stages of R. simulans. These results indicate that Rs4 and BnSm isolates can be effective as potential biological control agents for the control of R. simulans