The invention relates to a device for combating the varroa mite in a bee brood, comprising at least one middle wall that can be inserted in particular into a beehive and that is provided with brood cells for female bees, the device having an electrical heating device that has a resistance heating element embedded in the middle wall and a control device connected to the latter which is designed such that an automatically running heating process can be initiated with a temporally pre-determined heat-up phase that lasts until a temperature of 39° C. to 45° C., preferably 39° C. to 42° C., is reached at the bottom of the brood cells in the region of the resistance heating element and then with a subsequent phase of maintaining this temperature for a predetermined period of time.