Abstract: The plug comprises a body (1) permanently coupled to the neck of a container for an air freshener or insect repellent liquid, with evaporation occurring through a wick (11) axially coupled in a concentric passage of the plug itself. An inner part of the axial passage of the plug in which wick (11) is inserted is provided with slits (7) along the main generatrix line, forming sectors (9) provided with semi pyramidal projections (12), defining means which allow motion in the direction of insertion of wick (11) and prevent its displacement in the outwards direction for removing said wick (11) from the plug, which prevents the container on which the plug is applied from being refilled with a product other than the original.