A system and method for treating items suspected of insect infestation is described. The items are placed in a treatment space inside a treatment container together with a composition comprising one or more volatile components with insecticidal activity. The composition is applied to an absorbent material capable of containing the composition in a treatment amount; and the absorbent material and the composition are enclosed in a diffuser container with perforations covering about 1 to 30% of a surface area of the walls that allow diffusion of the one or more volatile components into the treatment space.