In this study, we have isolated and identified 5 bacterial isolates from European shot-hole borer, Xyleborus dispar (Coleoptera: Scolytidae), an important pest of hazelnut. After various morphological, physiological, biochemical and molecular characteristics were determined in detail, bacterial isolates were identified as Pseudomonas fluorescens (Xd1), Bacillus megaterium (Xd2), Bacillus thuringiensis (Xd3), Pseudomonas rhizosphaerae (Xd4) and Pantoea cedenensis (Xd5). Especially, the B. thuringiensis strain was identified in more detail as Bacillus thuringiensis subsp. tenebrionis (H8ab). The insecticidal activities were determined against the larvae of Agelastica alni L. (Col.: Chrysomelidae), Amphimallon solstitiale L. (Col.: Scarabaeidae), Leptinotarsa decemlineata (Say) (Col.: Chrysomelidae), and Melolontha melolontha L. (Col.: Scarabaeidae) larvae at 1.8 x 10(9) CFU/ml dose, within five days. The highest insecticidal activities are 100, 100, 80 and 100% for Bacillus thuringiensis subsp. tenebrionis (Xd3) on A. alni, A. solstitiale, L. decemlineata, and M. melolontha larvae, respectively. Our results indicate that especially B. thuringiensis subsp. tenebrionis (Xd3) may be valuable as a microbial control agent for coleopteran pests, respectively.