Moles dig underground tunnels, damaging lawns and root systems. Voles eat the roots of plants, such as hostas. Both can behave just like the rascally gopher in the movie "Caddyshack" and drive a gardener crazy. There are electronic devices and repellents aimed at controlling moles, which you can try. With voles, which mostly dig holes rather than burrowing tunnels like moles, I find that my dog is an effective repellant. Or terminator. Volminator, perhaps?