The behaviour of cell’s of wild-type strains 1 000 and 2–1 of Bacillus thuringiensis ssp. galleriae in liquid, semisolid (0,4 % agar, w/v) and solid (1,5 % agar, w/v) media was investigated. It was found that the populations of the investigated strains are heterogeneous and consist of two hereditarily fixed types of cells which are differ in ability to colonize media of different density. One type of cells effectively colonize media with a low density (0,2–0,4 % agar) due to swimming motility, but are not able to actively move through a solid medium. The second type of cells, by contrast, is unable to actively move in a semisolid medium, but can effectively colonize as the surface of a solid medium due to swarming motility, and of medium depth, through shaping the long (80 μm) septated and aseptated filamentous cells. In clonal cultures of both variants, alternative forms are arising with a high frequency.