Over the last few years the mole population has increased dramatically, this is thought to be partly due to the foot and mouth outbreak in 2001, when farmland was out of bounds to mole catchers, and the removal of strychnine as an approved poison for mole control in 2006.
In gardens most mole damage is aesthetic, but their tunnelling in borders can cause valuable plants to wilt and die, and I have seen rows of vegetables and fruit destroyed by mole tunnels.
In farmland, however, the damage can be more serious. If silage is contaminated by the soil from mole hills it can be spoilt, and when eaten by livestock can cause listeriosis, which can lead to the death of the animal. Expensive machinery can also be damaged by soil and stones pushed up by moles.
Nowadays it is considered that the traditional use of traps is the most humane and effective method of mole control.