Chestnut weevil, Curculio elephas L. (Coleoptera: Curculionidae) is the most effective pest of chestnut and oak all over the world. It causes approximately 25-30% economical damage to chestnut production per year in Turkey In this study, we investigated the bacterial flora of chestnut weevil collected in Black Sea Region (Turkey) during 1997 and tested it for the insecticidal activities. Based on colony colour and morphology, three isolates were determined. According to morphological, physiological and biochemical tests, they were identified as Bacillus lentimorbus, Pseudomonas fluorescens, and Esherichia coli. The insecticidal activities of these bacterial isolates on third-instar larvae of C. elephas were investigated. As a result, the highest insecticidal effect determined on C. elephas is 32% with B. lentimorbus. The effects of the rest of the isolates are 20% with P. fluorescens and 0% with E. coli.