Moles damage lawns by tearing up and killing grass, uprooting plants and leaving piles of dirt everywhere, according to Better Homes and Gardens. Most moles tunnel just a few inches under the surface, which exposes any grass or plant roots to air and causes them to dry out.
Moles don't actually eat plant roots; it is the drying out of the roots that explains why moles can kill such large areas of grass, notes the Michigan State University Extension.
Exterminating moles with a trap can stop the continuous damage to the yard or garden, recommends Better Homes and Gardens. However, the first step towards eliminating moles is to take care of any grub infestation in the soil, as this is one of a mole's favorite diets, notes the MSU Extension. If grubs are the problem, eliminating them may make the moles move elsewhere to find food.
If grubs are not the problem, a mole repellant may help get rid of the pests, according to the MSU Extension. However, this tactic only works against shallow-tunneling moles, as species like the star-nosed mole dig too deep for the repellant to have any effect. Generally speaking, the tunnels of shallow-digging moles are usually visible on the surface, whereas only the holes leading to the tunnels are visible for deeper-digging species.