B. ruderatus is common in western Europe, specially in its Mediterranean zone. In latitude, its distribution ranges from the Moroccan Atlas, N. Algeria, N. Tunisia and S. Italy to the south of Sweden, Lithuania and Belarus. To the west, the species extends to the whole Iberian Peninsula, Madeira, the Azores, and England. It is very rare in Wales and probably absent from Ireland. The eastern limit of its range is less clear, though it includes Poland, Hungary and Slovakia and seems to reach Ukraine. Efremova (1991) mentions some findings in the upper Volga (Ulyanovskaya Oblast, Kuybyshevskaya Oblast), i. e. largely beyond the main range of the species. In S.-E. France, Switzerland, Austria and Hungary, its distribution appears to be limited by that of B. argillaceus. B. ruderatus is also present in most of the Italian Peninsula, south of Toscana. Besides, B. ruderatus has been imported in New Zealand and in Chile.
Within this vast area, the species includes several subspecies. The nominal subspecies is the common form on Madeira and in the greater part of the Iberian Peninsula. B. ruderatus siculus is found in the far-south of Spain, in the north of Morocco, Algeria and Tunisia, in Sicily and the south of the Italian Peninsula. B. ruderatus perniger is found in the British Is. and is probably the origin of the populations exported to New-Zealand and Chile. B. ruderatus autumnalis lives in the larger part of W. Europe. The well differentiated subspecies corsicola and sardiniensis live respectively in Corsica and in Sardinia.
P. Rasmont