The leafroller weevil beetle ( Rhynchites bacchus L., Coleoptera: Rhynchitidae) is one of the most destructive pest of various fruits such as apple, plum, apricot, cherry and peach (nectarine) etc. almost all over the world. This pest feeds either stone or pome fruits and can cause up to 80-90% damage to orchards. In this study, we investigated fungal pathogens of this pest to find more effective and safe biological control agent against it. Insect specimens were collected from apple orchards invaded by R. baccus during July of 2007 in Gumushane, Turkey. One fungal species was isolated and characterized by currently used morphological and molecular techniques including ITS and the partial EF1-α sequencing. Based on these characteristics, the isolate was identified as Beauveria bassiana . Separately, the insecticidal activity of the isolate was determined on R. bacchus adults. The fungus caused 100% mortality within two weeks days after application of 1 × 10 8 ml -1 spore concentration and the LT 50 value of the fungus was calculated as 7.5 day. This is the first study to determine the effectiveness of B. bassiana against R. baccus .