In order to extract fiber flocks from fiber bales conveyed on a conveyor belt by very small steps in a predetermined direction of travel, an extraction member is moved over the fiber bales in a direction substantially perpendicular to the predetermined direction of travel of the fiber bales. For this purpose, the extraction member comprises a spiked opening roller driven by a motor. This spiked opening roller conveys, by rotary motion thereof, fiber flocks from the surface of the fiber bales into a fiber-flock conveying channel, in which the fiber flocks are drawn off by a fan and delivered to a conveyor channel. In this conveyor channel, which is likewise a suction fiber-flock conveying channel, the fiber flocks are fed via a connecting line or conduit to a fiber-flock processing location. For moving the extraction member over the fiber bales, the extraction member is provided with wheel shafts and wheels having a profiled tread for guidance along tube-shaped tracks. The wheel shafts are driven by a motor and an associated gearing. A control unit synchronizes the step-by-step forward travel of the fiber bales in the aforesaid predetermined direction of travel with the travel of the extraction member over the fiber bales.