Petaloudes is a nature reserve that is populated by butterflies from June to September: the Butterfly Valley, about 1 km long with steep streets, lakes and wooden bridges. It is a rare natural sight with thousands of butterflies resting in the trees. There is an entrance fee and visitors are advised to visit early in the morning for the fresh air and not to find crowds. The butterflies belong to the species Callimorpha quadri puntuaria (Spotted Harlequin), and gather here because they are attracted by the particular resin of a tree of the maple family, the "Liquidambar orientalis" with the strong and characteristic scent of vanilla