Abstract: A harvester is provided for mechanically removing cells from the internal surfaces of conventional, unmodified roller bottles. The device is a foldable, flexible arrangment which may be inserted into the neck openings of conventional roller bottles, without any, or only minor, modification thereof. Once inserted, the device of the invention mechanically expands to engage the internal surface of the bottle for the scraping thereof as the bottle revolves, thus effectively removing the cell growth rapidly and without the tedium of laborious hand scraping.