What are moles?

Moles are rarely seen as these mammals live mostly underground. They dig out a system of tunnels and chambers, and dispose of the excavated soil by throwing up molehills on the surface.

Moles don’t feed on plants, they are carnivorous feeding on invertebrates that fall into their system of tunnels. Any plant damage they cause is incidental to their lifestyle. Molehills on lawns should be removed before mowing and collapsed surface tunnels filled to maintain a level lawn surface.

Mole activity is usually greatest in late winter and early spring.

Moles are very territorial and in many cases the mole hills seen in a garden are the activity of just one individual. 

Symptoms

You may see the following signs of mole activity:

• The first sign of mole activity is heaps of excavated soil thrown up on the surface of lawns and flower beds (molehills).
• Moles tunnelling through the soil can disturb the roots of seedlings and other small plants in flower beds and vegetable plots

Control

Where possible moles can be tolerated. Should the activities of a mole be considered too disruptive there are several steps can be taken encourage them to move elsewhere  or control moles. Additional information on living with moles from the RSPCA (Adobe Acrobat PDF)

Mole netting

Netting is available which can prevent moles coming to the lawn surface to create molehills. This must however be installed before turf is laid.

Electronic devices

Electronic devices are available from some garden centres and mail order firms. Their buzzing noise is said to drive moles away; however this may only be to another part of the garden.

Mole repellents

A type of mole-repellent smoke, sold as Pest-Stop Biofume Mole Smoke, emits castor oil fumes. These are said to line the tunnels and deter worms and other mole food from entering the tunnels. The hungry mole may move elsewhere, or it may simply create new tunnels nearby.

Planting

Caper spurge, Euphorbia lathyris, which is a biennial plant, has its adherents who claim the root exudates repel moles. It is worth a try, but be sure to remove most of the flower heads before seeding occurs or the plant can become invasive. Bulbs of Allium moly are also sold as a mole deterrent but are of doubtful value.

Mole traps

Mole traps for killing moles are available from garden centres and hardware stores. When considering if this is a good option it should be considered that vacant tunnel systems are often taken over by another mole from nearby and so you may not be free of a mole for long. The tunnel or half barrel trap may be easier to use than some other designs. If used correctly they are considered humane method of control as death should be instantaneous when activated. However, this can be difficult to achieve as the mole is not always killed outright and consideration should be given to using an experienced professional. To find a local company search on-line.

• Mole traps need careful placement in a tunnel that is about 10-20cm (4–8in) below the surface, but not directly under a molehill
• The location of tunnels can be ascertained by scraping away a recent molehill and probing the hole with a pliable stick
• Open up a tunnel with the minimum of disturbance, using a trowel and carefully align the jaws of the trap with the direction and depth of the tunnel ensuring the trap fits tightly
• No bait is required
• Once the trap is set, gently cover it with an upturned bucket, a sod of turf or similar to exclude light and draughts
• Check the trap at least once a day
• The mole will sometimes push soil into the trap. If this happens, the trap will need re-setting

Live-capture traps are also available for setting in mole tunnels. These must be inspected at least twice a day so that the mole can be released before it dies of starvation and/or stress. Moles can die of stress even within this time. Captured moles should be released at least one mile away from the area of capture, permission to release the mole must be gained from the landowner and it must be released into an environment that can support the animal. Meeting these requirements can make the use of live capture traps impractical.

Hire a professional

Mole smokes for killing moles are no longer on sale to home gardeners. Professional contractors can be employed to use pellets that emit toxic gases into the tunnel system, but these cannot be used within 10m (32ft) of occupied buildings. This can be a expensive option. These pellets can be effective but freedom from moles may not last long if there are other areas nearby from which moles can soon recolonise the garden.

Biology

Live moles are rarely seen above ground. They are about 15cm (6in) long, with dense blackish-brown fur and broad front paws that are adapted for digging.

The main breeding season runs from February to June, and a female will have three or four young in a nest built underground. Outside the breeding season, moles lead largely solitary lives, so all the mole activity in a small garden is likely to be due to a single animal.

Moles feed on earthworms and other soil-dwelling creatures, not on plant roots.

Image: © GWI/Nicholas Appleby. Available in high resolution at www.gardenworldimages.com