Fecha de publicación: 17/07/1946 Fuente: WIPO "hive" 578,919. Photo - electric indication and control: TOMES, G. A. R. Feb. 9, 1944, No. 2393. [Class 40 (iii)] [Also in Group I] Imminence of swarming in beehives is indicated by a device attached to the queen-bee and an electrically responsive detector lodged in the hive on the way to the exit. The queen may be marked with a metallic foil disc inside which has been sealed radio-active material, the foil being approximately .0005 inch in thickness and of such a diameter as to be applicable to the thorax. The detector 8 is a Geiger-Muller tube which when energized operates an audible warning as well as four shutters 9, 10, 11, 12 controlling, respectively, the hive exit 6, the entrance to an empty chamber B, the exit from the vacated chamber A and a new entrance 12 thereto, such shutters being in the form of perforated grills. Luminous paint on the queen may be associated with a light-sensitive device such as a photo-electric cell.