Colorado potato beetle, Leptinotarsa decemlineata (Say), is a devastating pest of potatoes in North America and Europe. L. decemlineata has developed resistance to insecticides used for its control. In this study, in order to find a more effective potential biological control agent against L. decemlineata, we investigated its microbiota and tested their insecticidal effects. According to morphological, physiological and biochemical tests as well as 16S rDNA sequences, microbiota was identified as Leclercia adecarboxylata (Ld1), Acinetobacter sp. (Ld2), Acinetobacter sp. (Ld3), Pseudomonas putida (Ld4), Acinetobacter sp. (Ld5) and Acinetobacter haemolyticus (Ld6). The insecticidal activities of isolates at 1.8x10(9) bacteria/mL dose within five days were 100%, 100%, 35%, 100%, 47% and 100%, respectively, against the L. decemlineata larvae. The results indicate that Leclercia adecarboxylata (Ld1) and Pseudomonas putida (Ld4) isolates may be valuable potential biological control agents for biological control of L. decemlineata.