Abstract: A dust collecting bag with a central opening in the endwall thereof, which opening can be covered and uncovered by a cover flap hinged on the endwall of which it constitutes an integral part so that a portion of its free edge opposite the hinged mounting is positioned within the area of the opening. The central opening has at least one locking flap disposed along a portion of the edge opposite the hinged mounting of the cover flap and the portion of the free edge of the cover flap within the area of the opening has slits extending from the edge, with the portion of the cover flap defined by the slits being pivotable out of the plane defined by the remainder of the cover flap. The locking flap bridges the space between the cover flap and the edge of the opening.