Earth-conscious gardeners can use all-natural Molexit anywhere they want to deter tunnel making moles. Castor-oil-based Molexit comes in a dry granular formula and is easy to broadcast by spreader or scatter by hand. One 6.8-pound box covers up to half an acre. Extensive testing of Molexit done by the Department of Forestry at the University of Kentucky revealed no mole activity for up to six weeks in 80 percent of the treated area. Duration of effectiveness depends on soil and weather conditions.