Voles

Identification

Small rodents with a stocky body, short tail and blunt muzzle, about 9–13 cm long, active all year round. They dig shallow tunnels just below the soil surface. Symptoms: gnawed roots and bark at the base of trees and shrubs (girdling of trunks under the snow in winter), eaten-out bulbs and tubers, dying plants that pull out of the ground easily, and small mounds of excavated soil with numerous shallow burrow openings linked by nibbled runways in the grass. In garden practice the name refers above all to the plant-eating field voles of the genus Microtus. Their fur is grey-brown to reddish-brown, and their small but clearly visible eyes and ears distinguish them from the mole. They breed exceptionally fast — a female produces several litters of several young per season, which mature within a few weeks — so numbers can rise sharply in multi-year cycles (outbreak years), when the damage becomes severe. They do not hibernate; the worst losses occur in late autumn, winter and early spring, when green food is scarce and they switch to roots, bark and bulbs overwintering in the soil. Under the snow cover, sheltered from predators, they gnaw the bark around the base of young trees (girdling), which after the thaw shows up as sudden wilting or death of the tree. Most at risk are young fruit and ornamental trees (especially apple trees on weak-growing rootstocks), tulip and crocus bulbs, tubers, root vegetables, perennials, and plants stored in clamps and compost heaps; daffodil bulbs, being poisonous, are usually left alone. Characteristic signs are the even, smooth tooth marks on roots and bark, roots cut off just below the soil surface, and a network of shallow runs with numerous open exits — unlike the mole, whose mounds have no entrance hole.

Treatment

Planting bulbs, tubers and young trees in baskets of fine wire mesh (protecting roots and bulbs), wrapping trunks in wire or guards for the winter against bark-gnawing, and snap traps or live traps set in the active runs. It is crucial to remove cover — mowing tall grass, clearing weeds and compost — and to encourage natural enemies (buzzards, weasels, cats). Poison baits should be avoided because of the secondary poisoning of predators. Baskets are best made of galvanised mesh with openings of about 10–13 mm and buried so that they enclose the whole root zone; fit trunk guards low, down to ground level, and keep mulch away from the base of the trunk — mulch and tall grass give voles shelter and encourage them to gnaw the bark. Set traps in fresh, active runs (you can recognise them by exposing a section of the burrow: an active run is sealed up again within a day); trapping is most effective at low and medium densities, in early spring and autumn, before the population grows. It is worth encouraging predators by putting up perching posts for the buzzard and kestrel and nest boxes for the barn owl, and by tolerating weasels and cats — but this is limiting pressure, not immediate elimination. Repellent plants and repellents (crown imperial, garlic, caper spurge, ultrasonic devices, flooding the burrows) are sometimes recommended, but their effectiveness is poorly documented — treat them as a supplement to barriers and trapping, not as protection on their own. Chemical control in the home garden is a last resort: anticoagulant rodenticides are used only in enclosed bait stations or placed deep in active burrows, out of reach of non-target animals, precisely because of the secondary-poisoning risk mentioned; fumigation of burrows with phosphide products is heavily restricted by law and reserved for licensed operators, not for amateur use.

How to tell it apart from look-alikes

Control — organic and chemical methods

We give active-ingredient groups and modes of action, not brand names — specific products and their approval vary by country and are sometimes withdrawn. Always check and follow the current label.