The Extension service or other qualified farm advisor should be contacted to confirm diagnosis and help grower monitor populations. If economic thresholds are reached, appropriate control measures will be recommended, respecting the sustainable agriculture guidelines. Reporting these problems also serves as an alert to the industry at large that there may be a potential new problem facing the industry.

General Information on voles and their lifecycles, reprinted from:

Oregon State University

Voles

Voles, also called meadow mice, short-tailed mice, or orchard mice, are very similar to pocket gophers because they live much of their life below ground. Like gophers, a large percentage of their diet consists of roots. Unlike pocket gophers, they feed above the ground as well.

The first signs of vole activity are 1 to one and one-half inch open holes in the ground with connecting compacted paths. Because voles confine most of their above-ground feeding to these paths, clipped vegetation can generally be found around the open holes and along the runways.

If you were to begin digging at one of the holes you would find a second runway, just below the soil surface, where these animals spend the rest of their time feeding on plant roots. Digging a little deeper, you would find another set of burrows 6 to 8 inches below the soil surface where they store (cache) food, build nests, and rear their young.

Unlike gophers, which breed only once during a season, voles begin producing their litters in late February and every 21 days thereafter. With litters ranging between four and six per female, a population can soon grow to astronomical proportions.

Indirect management

Changing the voles' living conditions by either reducing or eliminating their food source and protection (habitat) will have the most pronounced and long-lasting effect. When food sources are eliminated voles will, because of their small territories, generally die. Some will migrate.

Weeds and grasses around plants, and hills of mulch around the crown, should be removed as they encourage feeding by voles. All dead and dying plant material should be raked from beneath the plants. Excessive ground cover provides an excellent form of protection for the voles, particularly during the winter when the mulch becomes a thermal blanket for the ground.

Direct management

Traps and fumigants (gases) are ineffective for vole control. Traps will only catch a few of the animals that venture above the ground. Fumigants will escape from the many open holes of the burrow systems.

Toxicants

(poisons) used in baits can, if used properly, provide control within a short period of time. Baits should be scattered or placed around each burrow opening and in the voles' runways between holes during the fall and early winter when the animals are the most active above the ground. Check with your local county Extension office for those registered.

Further information:

http://www.ipm.ucdavis.edu/PMG/PESTNOTES/pn7439.html University of California at Davis

http://www.pestcontrol-products.com/rodent/voles.htm Internet pest control site with great photos

http://www.pmra-arla.gc.ca/english/consum/molesandvoles-e.html Canadian Agriculture Link