An air ventilator for beehives is provided which produces positive ventilation of a hive in an extremely simple and inexpensive manner. The ventilator is mounted on the hive so as to communicate with an outlet aperture which is conventionally provided in a hive to afford convective ventilation. The ventilator includes a first tubular portion or tube which extends perpendicular to the hive and a second tubular portion or tube which is formed integrally with and extends transverse to the first tube. The end sections of the second tube are of greater cross-sectional area than the portion of the second tube adjacent to the first tube, and comprise flared cones in an exemplary embodiment. Thus, when there is air movement in the direction of the second tubular portion, the stagnation pressure established within these end sections produces a suction effect in the portion of the second tube adjacent the first tube that draws air out of the hive. Moreover, the transverse air passages provided by the tubes prevent direct wind blasts from entering the hive through the outlet aperture.