Apparatus and methods for controlling insects. Some embodiments provide apparatus (for instance patches) comprising one or more layers of degradable materials impregnated with respective insect-control materials. A first impregnated layer defines an effective thickness and degrades at a rate dependent on an environmental factor to thereby expose a portion of the insect-control material impregnated therein at a depth corresponding to the decreased thickness. As the first degradable layer degrades in a multi-layer insect-control patch it also exposes the second layer (which is attached to the first layer) at a rate corresponding to the degradation of the first layer. A barrier impervious to the second insect-control material can be attached to the second layer. In some embodiments the first and second degradable materials are the same material and the second impregnated layer is formed on the first impregnated layer thereby bonding them together.
