B. argillaceus is a typical East-Mediterranean species. Its distribution has been drawn by Reinig (1939) and may be compared with that of its sister-species B. ruderatus in fig. 40.
To the west, the range of B. argillaceus extends in France to the upper valleys of the Alps and in Switzerland to the upper Rhone. It is found throughout N. Italy and in most of the Austria. The northern limit of its range runs through Slovakia. In Hungary, it is found everywhere. In Romania, it extends to the region of Cluj. It has been found in Moldavia and in Russia up to Kursk and Volgograd. To the east, Skorikov (1931) mentions it from E. Kazakstan. South and south-east, B. argillaceus is found throughout the Balkanic Peninsula, in Creta, Cyprus, Turkey, Caucasus, Transcaucasia and N. Iran, including the Kopet-Dag. Despite ancient erroneus citations, the species is totally absent from the Iberian Peninsula.
There may be a geographical exclusion between B. argillaceus and B. ruderatus ; however, there are restricted zones of sympatry, as in some valleys of S. France and Switzerland and in Hungary.
P. Rasmont