Abstract: A marker for an electric fence to warn persons of a long span of bare wire is preferably fabricated from insulating plastic that is stiffly elastic. A groove across a face of a piece of the plastic is somewhat deeper than the diameter of the wire to which the marker is to be attached and is somewhat more narrow so that the wire can be pressed firmly into the groove. The piece of plastic is therefore prevented from sliding along the wire by being gripped within the groove. A streamer is threaded over the plastic piece such that it cannot readily contact the wire.