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Mole hills - piles of fresh, excavated soil - don't fully convey the extent of one mole's underground tunnel system, which can cover a surprisingly large area. If a young plant isn't developing, it could be due to tunnelling beneath it. Seedlings can also suffer badly when their roots are disturbed, or they're left dangling in an empty space. Before mowing a lawn with mole hills, sweep up the soil to avoid smudging it across the grass.
Solution
Organic
Mole traps are very effective. Insert one in a tunnel, cover it with turf and an upturned bucket to exclude light, and check it daily. Electronic devices are available that emit a buzzing sound to drive moles away, either to the other end of a large garden or to your neighbour's garden!
Chemical
Professional contractors can gas the tunnels, but only if it's 3m away from occupied buildings. And this won't prevent other moles from tunnelling into your garden.
