Insecticides that have high vapor toxicity and dissipate rapidly after application appear promising for use as space treatments that can be used against stored product insects in food storage areas without leaving hazardous residues. To apply vaporized insecticides in large storage areas, a dispenser was needed to provide an immediate buildup of an effective vapor concentration, distribute the vapor uniformly throughout a storage area, and maintain a constant vapor concentration lethal to the insects for the necessary period. A vapor dispenser designed to meet these requirements was developed. The basic principle of this dispenser is to accelerate the release of vapors of an insecticide impregnated into resin pellets by passing a stream of heated air through an aggregate of the impregnated pellets.