Osmoderma eremita, the hermit beetle or Russian leather beetle, is a species of European beetle in the Scarabaeidae family. Adults reach between 28 and 32 mm in length. The larvae develop in hollow trees. Oak is the most important tree species, but the larvae may develop in any tree species with suitable hollows. Due to habitat loss and fragmentation, the species has decreased all over its distribution range. For that reason the species is protected in most European countries, and has been given the highest priority according to the EU's Habitats Directive. O. eremita can be found everywhere in Europe, except for The United Kingdom, Iceland, Ireland, Malta, Portugal, and San Marino.