Fuente: WIPO "varroa" In one example, a heatable centre wall for a beehive is provided for the hyperthermal reduction of varroa and/or for heating honeycombs for maximizing the harvest yields. The centre wall includes a continuous PTC (positive temperature coefficient) heating foil having a non-linear PTC (positive temperature coefficient) effect. As well, the PTC (positive temperature coefficient) heating foil has on at least one of its sides a layer having a comb pattern.