Moles have been having a running battle with gardeners for centuries. As your experience demonstrates they are still considered a problem in many gardens, where molehills spoil formal lawns and the extensive runs undermine plants in borders.
Activity is most noticeable in spring when new runs are being established.
Moles spend most of their life underground with a single family occupying up to half an acre of land. However, contrary to popular belief, moles do not actually damage plants by grazing the roots. The traditional method of removing moles from a site was to employ the services of a mole catcher, who inserted traps into runs to catch and kill the moles. This is still an option for gardeners. The disadvantages are that once the moles have been exterminated it is highly likely that a new family will move into the previously established runs.