A device, comprising a substrate and a shutter, for release of an active ingredient (AI) in a temperature range of T1 to T0. The substrate comprises the AI and a matrix from which the AI substantially only diffuses above temperature T1. The shutter comprises one or more heat sensitive members that may be made of bimaterial and shield the substrate from the atmosphere above temperature T0. The AI may be a repellent, insecticide or pesticide that may target a pest active within the temperature range. The matrix may be polymeric with a glass or first order transition temperature T1. A foil comprising a plurality of heat-sensitive members and apertures arranged to be open or closed dependent upon the temperature. The apertures may be arranged in an array, they may open or close at different temperatures and in different directions. The foil may be laminated with a layer containing an AI.
