Kapıdağ Peninsula is located on the south coast of M arm ara Sea, between Erdek on the \vest and Bandırm a G ulf on the east. The aim of tlıls study is to has been conducted determ ine the Lepidoptera Fauna and the im portant species destructive to forest trees of the Kapıdağ Peninsula. The research behveen the years of 2004-2005. According to results of this the study 86 species of 19 different fam ilies w ere distiııgııeslıed living in this area.