Liquid Fence Mole Repellent Concentrate is long lasting. In independent lab testing by a third party independent laboratory, Liquid Fence Mole Ready-to-Spray provided excellent overall results, with an astonishing 99% reduction in mole activity, even 4 weeks after treatment. It is formulated to coat earthworms and grubs, the main sources of food for moles. This creates a very undesirable meal, forcing these destructive nuisances to look elsewhere for food.