Bombus laesus belongs to the laesus-group (formerly sg. Laesobombus), together with the near species or subspecies Bombus mocsaryi. Depending on the authors, these two species are separated or lumped together as subspecies of the same taxon laesus. As the queens and workers of laesus s.s. very closely recall those of B. muscorum, to the point that they can be undistinguishable, one should rely only on the males in the region where these species co-occur.
Bombus laesus s.s. is present in S.-E. Poland, Hungary, a few isolated specimens in Serbia and Macedonia, in Ukraine, the Volga basin, Kazakstan, the Caucasus region, Anatolia and N.-W. Iran. Within this wide range, the species is common only in some rather restricted zones, as Hungary and the region extending from Turkey to Iran. The steppic distribution of Bombus laesus laesus reminds of that of an other steppe species: Bombus fragrans.

P. Rasmont