October, 1997

Many different ways to control voles in orchards

By Glenn Dudderar
MSU Fisheries and Wildlife

Field mice, also called meadow mice, are wild, short-tailed, brown mice more properly called voles. Meadow voles, pine voles, and prairie voles damage fruit trees, Christmas trees, ornamental trees and shrubs, and grassy areas throughout the state. Meadow voles are found statewide and make shallow (one- to three-inch) tunnels in the ground and surface runways in the grass. They also girdle tree trunks in fall and winter.
Pine voles occur in scattered populations on the west half of the state and dig deep (one- to three-foot) tunnels, but make few surface runways. They girdle tree roots. Prairie voles are found in southwestern Michigan and the evidence of their presence resembles both the meadow and pine vole's.

Update on populations

The trapping and observations that I have done this summer indicate that there are high vole populations in some areas of Michigan, in particular southcentral and northwest Michigan. Vole populations in northeast Michigan seem low. I do not have information about western Michigan and the Upper Peninsula.

Biological control

A variety of wild animals feed on voles: hawks, owls, crows, ravens, weasels, foxes, coyotes, bobcats, raccoons, skunks, shrews, domestic cats, and some species of snakes. Of these, the hawks and owls (raptors) and snakes can be encouraged to feed in orchards, tree plantations and grassy areas. Note that predation will not prevent large, periodic increases in vole populations, but may eliminate enough individuals in normal years to prevent some damage.

Cultural control

Meadow voles live in tall grass, brush-grass mixtures and under artificial cover (hay bales, boards, cartons and crates, brush piles) in grassy areas, etc. Reduce this habitat by mowing, using herbicides and removing cover.

Mechanical control

Trees and shrubs can be encircled with a protective barrier to prevent voles from gnawing the bark.

Repellents

Both voles and rabbits can be repelled from trees and shrubs for up to 90 days by applying a solution of 20% thiram and sticker (an adhesive) to all bark surfaces vulnerable to gnawing.

Population reduction

Vole populations can be reduced in orchards, tree plantations and grassy areas by evenly applying or broadcasting toxic baits containing the restricted use pesticide zinc phosphide or diphacionone to grassy areas from September to December. Do not place baits in piles or on bare soil. Research has shown that bait in piles or on bare soil is least effective in killing voles and is most hazardous to non-target wildlife and pets. When voles invade an orchard or tree plantation by traveling under snow or when ground vegetation is sparse, bait dispensing stations should be used.