A skimmer for a pool includes a skimmer guard that is installed by friction only, and without the use of separate fasteners. In one embodiment, the skimmer guard includes a perforated portion surrounded by a peripheral lip, the lip being shaped for engagement with a flange formed on a frame mounted to a skimmer opening. The skimmer guard is inserted onto the flange, and thus prevents debris from entering the skimmer. In another embodiment, the skimmer guard includes a perforated face plate and a plug, the plug being sized for frictional engagement with a skimmer opening. In all cases, the skimmer guard is inserted without the use of separate fasteners, and without the use of tools. The skimmer guard can be removed and replaced with a non-perforated version, at the end of the swimming season.