Abstract: A beehive heater for installation between the lower brood chamber and the bottom board of a standard beehive for protecting a colony during the winter with a minimum of winter brood production and for accelerating spring brood production. The beehive heater provides an insulating curtain of heated air adjacent to the walls of the brood chambers. Air enters a plenum chamber where it is heated by a low temperature heating element and flows out of the plenum chamber through a series of holes located adjacent to the periphery of the lower brood chamber to form the insulating curtain of heated air adjacent to the walls. A landing board and entrance is provided near the upper edge of the beehive heater as means for the bees to enter and leave the lower brood chamber. The temperature of the air in the plenum chamber is thermostatically controlled with the control point adjustable so that it may be set for winter or spring operation.