Gas or vapor dispersing apparatus

Apparatus for dispersing a gaseous or vaporized pheromone into the atmosphere, comprising a first housing within which at least one pheromone-releasing source holding means is located, the housing having at its top and outlet, upward-draft creating means provided on said first housing which has adjacent to or below the, or each holding means, air introducing means, wherein the upward-draft creating means is mounted over the outlet, and comprises a series of annular vanes, the uppermost and lowermost of which are parallel and of frusto-conical shape or substantially of frusto-conical shape, a central aperture in each said vane, a common axis about which the vanes are centered and arranged in predetermined vertical spaced relationship, a plurality of supports parallel to and radially spaced from said axis, the lowermost of said vanes converging inwardly toward the next upper vane which is usually horizontal and planar in a diameter towards the common axis but may have a frusto-conical profile of shallower angle than the uppermost and lowermost vane forming a venturi, a device of aerodynamic shape mounted co-axially with the vanes and located between the upper two vanes, the device masking but not closing the central apertures in said vanes, and having upper and lower cone-like or dish-shaped air-deflecting walls arranged base-to-base about said common axis, the upper wall of the device being parallel or substantially parallel to the uppermost and lowermost vanes.