Castor Oil! Yep, they have it in the sprayer connector that fits on your hose with the proper dilution. The first year we had a problem we were told to use it and it worked like a charm. The second year (they will try and try again each year) we thought we would try a name brand mole repellant and it didn’t work at all. Back to the castor oil and haven’t seen hide nor hair of a tunnel. We keep up with it every 30 days or so and it doesn’t hurt the shrubs or flowers in the garden. I would however suggest that you rinse any herbs you use out of your garden that has been sprayed thoroughly as castor beans are VERY poinsenous and I would want to take any chances. I found this stuff at a Southern STates store and have had to have them order it. Good Luck!