Abstract: An annular guard (20) for mounting on a high voltage insulator extends laterally thereof for a sufficient distance so as to prevent small wildlife such as squirrels from forming a short circuit between the opposing ends of the insulator at high voltage and earth potential respectively. The guard (20) is formed in two planar parts (24, 26) that are pivoted together (28) so that they can be relatively rotated between an open condition for mounting onto a live insulator and a closed condition for being secured thereto. Overlapping regions of the two parts are secured together (30, 32, 34, 36, 38) in the closed condition.