Question
I am relatively new to gardening and have recently planted many bulbs and plants and want to preserve my investments from varmints. I live in MA and believe I have a vole problem in my yard. I was walking on my lawn when a large area, approx 10-12" sunk down 2-3"...I did not investigate further but filled it with soil and planted seed on top. I have 3 cats that have occasionally "captured" what I thought was a mouse, but further investigation tells me it was a vole. I have put a lot of time, hard work and money in my yard and would like to eradicate this problem pronto.  My questions are:  How can I kill these varmints without harming my pets?  How deep do voles dig their tunnels?  Am I able to protect my raised bulb bed by digging and placing a deep underground fence while ridding my yard of these pests?  Will they destroy the grass too as my lawn has never perked up and looks anemic compared to others in my neighborhood. Am I able to do something effective NOW,(as it is almost November), to prevent them from making my yard their smorgasbord?
Any suggestions would be greatly appreciated. Thank you.

Answer
Controlling Vole Damage

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Damage Identification
Sign found at the scene will help you identify the species causing damage. The presence of prairie and meadow voles in an area is demonstrated by their characteristic surface runways, which are most visible after the snow melt (Figure 3). The runways consist of closely clipped vegetation, about 1 to 2 inches wide. Small holes lead to underground runways and nesting areas. Pine voles have extensive underground runway systems, and spend little time above the leaf litter and ground cover layer. Damage that is primarily underground (versus aboveground) coupled with the absence of surface runway systems is typically caused by pine voles.
Voles usually damage woody plants during late fall through early spring. Voles tunnel through snow, and may gnaw on trees and shrubs up to the height that snow accumulates. Individual tooth marks (about 1/16 inch wide and approximately 3/8 inch long) may be visible on the wood after winter vole damage (Figure 4). The gnawing marks left by voles will be irregular in appearance and at various angles. In contrast, rabbits leave tooth marks that are about 1/8 inch wide and very regular. Pine voles, and occasionally meadow and prairie voles, tunnel below ground and feed on roots of trees and shrubs.
Voles have been known to travel tunnels developed by moles to gain access to flower bulbs and other plant roots. Damage of this type is often mistakenly blamed on moles. Moles feed on insects and earthworms and rarely consume plant materials.
Controlling Damage
Voles don抰 always cause significant property damage. Populations of voles, however, can increase quickly and be cause for concern. Generally, a direct relationship exists between populations of voles and the expected overall level of damage. Before undertaking control, consider the extent of the problem in relation to the cost of control. For example, a few voles could damage a highly-valued tree or flower bed and warrant control. At other times, they may go virtually unnoticed, making control unnecessary.
It is usually more cost-effective to prevent damage caused by voles than to control vole populations after damage has occurred.

Habitat Modification
Reduce the suitability of habitat for voles to lessen the likelihood of future damage. High vole populations cannot become established without food and protection from predators. Grass and weeds can be controlled around young trees and shrubs through cultivation, herbicides, and mowing. Normal cultural practices employed in establishing windbreaks, orchards, and other woody plantings often are effective in reducing habitat and potentially high populations of voles. Remove bird feeders or substantially reduce spillage from feeders to help lower the availability of food for voles.  Although drastic, voles are less likely to traverse weed-free zones that are 15 feet wide. Voles from adjacent areas, however, may use the cover of snow to invade even the best manicured property. Thus, although habitat modification is critically important to reduce vole damage, it is often not enough to end vole damage near woody plantings.

Exclusion
Exclusion can be used to protect highly-valued flower beds, gardens, shrubs and trees from vole damage. Install woven wire or hardware cloth fences (1/4-inch or smaller mesh) around small flower beds or gardens to reduce vole activity. The fence should be about 12 inches high and the bottom should be buried 2 to 3 inches into the ground. Where pine voles are a problem, the fence should extend about 6 inches below-ground as well. Rabbits and ground squirrels will also be excluded if you make the fence 18 inches tall and bury it into the soil a few inches.
Use ?inch hardware cloth or plastic cylinders to protect individual trees and shrubs. (Figure 5). Again, the cylinder should be tight to the ground or buried slightly and should extend higher than the maximum depth of snow in winter, including drifts.  The height of the cylinder should be at least 18 inches above the snow depth, if possible, where rabbits are also a potential problem. When making the cylinder, overlap the edges at least 1 inch and fasten it securely so gaps do not form that could admit voles. Cylinders of galvanized hardware cloth should last about 5 years, so make them large enough in diameter to accommodate expected trunk growth if they remain in place during the growing season.

Repellents
Various repellents made with thiram and "hot sauce" are registered for controlling vole damage on ornamental plants. They are not registered for use on gardens or plant parts destined for human consumption.
Repellents are relatively expensive and provide only short-term protection. Precipitation may wash some off. When foods are in short supply, such as in winter, the effectiveness of repellents usually decreases. Avoid using electronic repellent devices, moth balls or other unregistered products as no evidence has been produced regarding their effectiveness on voles.

Traps
Voles can be controlled by trapping if the damage is over a limited area (less than an acre) and a sufficient number of traps are used (3 per runway and/or hole). Set single mouse snap traps perpendicular to vole runaways, with the triggers in the runways, or set 2 traps together within the runway, with the triggers facing away from each other (Figure 6). No bait is needed, if you prefer to use bait, peanut butter mixed with oatmeal can be placed on the trap triggers. Baited traps should be covered with a box with a 1-inch hole cut in it, to reduce attractiveness and access to birds and squirrels. Make sure the box is securely positioned and of sufficient size to allow free action of the snap trap. Pvc pipe and cardboard milk cartons can make good enclosures.
Multiple catch mouse traps have also been useful in catching voles, especially meadow and prairie voles. Several voles can be captured at one time, fewer are needed and non-target species can be released alive. Locate a trap near visible burrows and adjacent to vole trails. Place a small amount of seed material, either bird or grass, at both entrance points. If the location is correct, the trap(s) should contain a few voles in 24 hours. If you catch nothing after 2 fair-weather nights, move the trap to a new location.

Toxicants
Large vole populations can be reduced most effectively with toxic baits. Zinc phosphide is federally registered for controlling voles and is available in formulated pellets or treated grain. It usually is a Restricted Use Pesticide that may be purchased and used by Certified Pesticide Applicators only. Contact your local Extension Educator for information on becoming a Certified Pesticide Applicator. Some formulations of zinc phosphide are packaged in small containers and are registered as General Use Pesticides, that can be purchased and used by the general public. You may find that the toxicant is most effective when administered in the fall and early spring when voles have few alternative food sources. Pre-baiting with untreated oats or pellets for 2-3 days may help improve bait acceptance and thereby increase the toxicant抯 effectiveness at reducing the vole population. To reduce the potential for affecting non-target species, avoid placing pre-bait or toxicant on bare soil or in piles.  Use zinc phosphide during a period of fair weather to protect the toxicant from moisture.  The use of bait stations will further decrease the risk of non-target species and moisture from reaching the toxicant. Contact your Extension Educator on where to obtain them.
Read all pesticide product labels thoroughly and comply with all directions given.
Zinc phosphide baits can be applied by hand in spot treatments by placing it in runways or burrow openings. Hand-baiting is the only application method that can be used in urban areas and lawns, ornamental plantings, parks, and golf courses. When placing toxicant in pine vole holes take care not to damage the hole or surrounding area. Pine voles are very fastidious. Any disturbance may result in the pine vole 搒weeping?the toxicant out of the burrow during its cleaning activities.
Toxic bait also may be broadcast according to label directions. This technique is most appropriate in young woody plantings or orchards, when efforts to reduce habitat have failed to reduce vole populations. Note that broadcasting increases the amount of bait applied per acre as well as the chances of harm to non-target wildlife. Before baiting, mow the grass to increase the amount of bait that reaches the trails and burrows used by voles.
Zinc phosphide pellets are also registered for in-furrow applications when planting corn or soy beans in minimum tillage systems. Specialized application equipment is required. Contact your local Extension Educator for more information.
Fumigation
Gas cartridges and aluminum phosphide tablets may be used to fumigate vole tunnels. Fumigation is very time consuming and often not very effective due to the complexity of vole tunnels. Aluminum phosphide is a Restricted Use Pesticide.

Safety & Health Precautions
Use pesticides safely. All toxicants and fumigants used to control voles can be hazardous to humans, pets, livestock and non-target wildlife if used improperly. Only use products that are registered for voles by the U.S. Environmental Protection Agency. Read pesticide product labels carefully and comply with all directions given. Seek assistance from your local Extension Educator, if necessary.  Use of toxicants inside tamper-resistant stations reduces the risk to non-targets.
Voles are not known to be a significant threat to human health and safety. Nevertheless, voles have been implicated in the transmission of tularemia and have been known to be hosts for agents of other infectious diseases, such as babesiosis, Lyme disease, giardia, and Rocky Mountain Spotted Fever. Reduce the risk of contracting diseases by wearing gloves, washing hands, using insect repellent, and avoiding contact with voles, including their urine and feces.  

Integrated Pest Management
As in most situations with vertebrate pests, a combination of methods may be more effective than relying on any one method for controlling vole damage. Most problems with voles in urban and backyard areas probably involve small populations of voles that can be controlled with habitat modifications, fencing or exclusion, trapping and repellents. Non-urban damage situations may involve larger populations of voles over greater areas, and can be dealt with by habitat modification, repellents, and toxic baits when necessary. Finally, readers should continue to monitor for new and renewed vole activity. Given their incredible reproductive rate, new infestations can seem to appear 搊ver night.? A quick and appropriate response to new vole damage can significantly reduce the amount of effort and associated costs needed to control the problem.  More information can be found at http://wildlifedamage.unl.edu or with your Extension Educator.

Characteristic   Prairie Vole   Meadow Vole   Pine Vole
Length (head & body)   5.4-7.0 inches   3.5-5 inches   2.8-4.2 inches
Tail Length   0.9-1.8 inches (less than twice the length of the hind foot)   1.4-2.6 inches (at least 2x the length of the hind foot)   0.6-1.0 inches (less than or equal to the length of the hind foot)
Adult Fur   Dark, brownish to blackish   Coarse, dark brown mixed with black   Soft, auburn, lacking guard hairs
Eye Size   Small   Large   Small
Nest Placement   Above or belowground about 4.75 inches.   Usually aboveground, but occasionally in shallow burrows   In burrows, usually less than 1 foot deep
Food   Grasses, some tubers  roots, and seeds,    Grasses, sedges, seeds, grain, bark, some insects   Bulbs, tubers, seeds, and bark
Damage   Girdle tree trunks at or near ground surface; may girdle higher under cover of snow; sometimes damage roots   Girdle tree trunks at or near ground surface; may girdle higher under cover of snow; sometimes damage roots   Girdle crown and roots


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