The entomopathogenic bacterium Bacillus thuringiensis is the most widely used biopesticide. In this study, to find and identify the more toxic B. thuringiensis strains against coleopteran pests, we isolated a B. thuringiensis strain (Xd3) from European shot-hole borer, Xyleborus dispar (Coleoptera: Scolytidae), a higly damaging pest of hazelnut. Based on various morphological, physiological, biochemical, and molecular characteristics, the bacterial isolate was identified as B. thuringiensis subsp. tenebrionis (naorrisoni) serovar H8a8b. This isolate was compared with the reference strains by scanning electron microscopy, SDS-PAGE analysis, cry gene content, and insecticidal activity. Isolate Xd3 forms a flat-square inclusion containing a protein component of c. 70 kDa. PCR analysis showed that the Xd3 has a cry gene, cry3. Toxicity tests were performed against coleopteran species. One hundred percent mortality was observed against larvae of Agelastica alni (Coleoptera: Chrysomelidae). The others were 90% for Amphimallon solstitiale (Coleoptera: Scarabaeidae), and Melolontha melolontha (Coleoptera: Scarabaeidae). Our results indicate that B. thuringiensis subsp. tenebrionis (Xd3) may be valuable as biological control agent for coleopteran insects.