Products containing castor oil have been used as a mole and vole deterrent for years as these burrowing animals are known to detest the scent! Strongly scented herbs, like garlic, chives, and peppermint, are also repulsive to moles and voles, as are products containing capsaicin (the ingredient that makes hot peppers hot!) Depending on your gardening size and style, you can try companion planting with herbs like chives, or you can use a spray-on product like Garlic Barrier to keep these pests away from your garden beds.