Voles and Deer Mice

Taxonomy

Domain	Eukarya
Kingdom	Animalia
Phylum	Chordata
Class	Mammalia
Subclass	Theria
Order	Rodentia
Suborder	Myomorpha
Family	Muridae
Subfamily	Sigmodontinae
Genus	Peromyscus

Scientific Name

Peromyscus maniculatus

Common Name

deer mouse

Compiled by Whitney Cranshaw, Colorado State University:

Microtus spp. (“voles”)
Peromyscus spp. (“deer mice”)

Hosts

Most damage occurs to small trees. Both conifers and deciduous trees are affected. Fruit trees in orchards are among the more valuable species with recurrent small rodent problems. In certain areas, mature aspen in the mountains show considerable superficial bark injury from voles feeding under winter snow.

Damage and Diagnosis

Vole damage.

Voles (also called “meadow mice”) and deer mice injure fruit and ornamental trees and shrubs by gnawing on the bark. Extensive injury produces girdling wounds that can kill smaller plants. The small size (about 1/8 inch wide) of the chewing wounds differs from those of other gnawing animals, such as rabbits. Small rodent damage to tree bark is most frequent during the winter. They will eat almost anything green, including grasses, tubers, bulbs and garden plants. They also commonly damage lawns by clipping grass while making surface runways.

Voles are very similar in shape and size to the familiar house mouse. The various species are separated by such features as fur color, tail length, and tooth arrangement, in addition to their distribution and typical habitats in which they occur.

Life History and Habits

In this region, there are at least five species of voles in the genus Microtus and six species of “deer mice” in the genus Peromyscus. The pine vole has been particularly damaging to orchards, and the meadow and prairie voles have done damage to bark of seedlings in nursery settings. The deer mouse (P. maniculatus) can also be a pest of trees. Their food base during the warm months contains a high complement of insects and succulent plant parts, with their winter diets being more reliant on seeds and bark. These two genera actively feed and reproduce throughout the year. Peak breeding occurs during spring and summer. Several young are produced in each litter, which develop rapidly and become full-grown in about six weeks. Their life span is fairly short, averaging less than one year. Population numbers fluctuate greatly, with peak injury to trees and shrubs associated with periodic outbreaks, particularly during the winter. They produce and maintain runways and shallow tunnels that cross the soil surface. Of necessity, in winter these runways are used and maintained beneath the snow.

Management

Natural predators of voles and mice include large snakes, shrikes, hawks, owls, weasels and predaceous mammals, including domestic cats.

To occur in large numbers, these rodents require cover and ready access to food. Mowing and other types of weed control in, around, and near tree-growing areas can reduce favorable cover. Mulches also provide cover for small rodents. To reduce bark feeding, mulch should be kept at least a few feet from the base of susceptible trees and shrubs. The depth of mulch should also be kept to a few inches.

Individual trees and shrubs can be protected from rodent injury by tree guards or wire mesh screening, 1/4 inch or less in diameter. Because these little animals can tunnel, the barriers should be buried 6 inches. Placing small, sharp pebbles in planting holes for bulbs can also deter them. During the winter, compacting the snow around trees and shrubs can act as a barrier to vole tunneling. Mouse traps, placed with the trigger along the runways, can be used to kill small rodents. Baiting is not necessary if traps are properly placed in the runway.

Hot pepper sauce and thiram-based repellents have been registered for control of meadow voles. Their effectiveness is considered questionable.

The information herein is supplied with the understanding that no discrimination is intended and that listing of commercial products, necessary to this guide, implies no endorsement by the authors or the Extension Services of Nebraska, Colorado, Wyoming or Montana. Criticism of products or equipment not listed is neither implied nor intended. Due to constantly changing labels, laws and regulations, the Extension Services can assume no liability for the suggested use of chemicals contained herein. Pesticides must be applied legally complying with all label directions and precautions on the pesticide container and any supplemental labeling and rules of state and federal pesticide regulatory agencies. State rules and regulations and special pesticide use allowances may vary from state to state: contact your State Department of Agriculture for the rules, regulations and allowances applicable in your state and locality.