A deterrent device 10 comprising an elongate body 11 formed from an extrudable insulating material. At least one, preferably two, elongate braided or knitted metallic conductors 19 are provided on an upward facing surface of the body, the material of the body penetrating into the lower margins of the or each conductor thereby securing the or each conductor to the body with the upward facing surface of the or each conductor being exposed. This construction enables the conductors to be co-extruded with the body thereby avoiding the need for further fastening devices and enables manufacture in a single operation. The upward facing surface of the elongate body preferably has two elongate sloping surfaces 13, 14 which meet at a central apex 15, the conductors being provided on each slope. The elongate body incorporates a lengthwise hollow opening 18. Preferably the elongate body is made from PVC and the metallic conductors from steel.
