Ant caps (termite shields) are designed to force termites to go around the edges of the metal so that they can more easily seen, rather than working their way through the timber in a more concealed manner. Ant caps are more useful with timber piers as the termites may travel through the centre of the pier and only emerge while attempting to go around the cap. However there may be a crack in the concrete pier that termites can allow for concealed access. The images show how this works.