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Pine voles prefer a light loamy soil. They live primarily in a series of connecting underground tunnels that are usually less than 1 foot deep. Entrance holes 1-2 inches in diameter may be noticed in gardens, home orchards, near trees and shrubs or in plant beds. The subterranean habits of pine voles makes controlling these animals difficult. Occasionally they will come above ground to forage on vegetation. You may sense a spongy feeling while walking on ground underlaid with numerous subsurface tunnels. The principal foods are bulbs, tubers, seeds and bark (root bark included), but they have been known to damage roses, fruit trees, bulbs, ornamental trees, shrubs,and flowers as well as vegetable garden plants. The total length (head and body) of the pine vole is from 3 to 4 inches. They have a relatively short tail, less than 1 inch in length, and it is less than or equal to the length of the hind foot. The adults' fur is smooth, soft, chestnut brown in color and lacks guard hairs. Their eyes are small, and ears are inconspicuous. Pine
voles produce several litters of young per year, usually from March
to November. Litters average about 3 offspring each. The young are
ready to breed in 2 or 3 months. Pine voles can have a high survival
rate because their underground habits help protect them from predators.
Family units maintain year-round exclusive territories. In
many cases the damage from pine voles goes unnoticed until the owner
discovers the decline or death of a particular plant. In vegetable
gardens entire plants may be pulled partially or entirely underground.
Wilted plants with chewed roots are commonly observed. In flower
and bulb gardens, plants may fail to grow in the spring after underground
tubers, roots and bulbs have been consumed by pine voles. At times
the entire root system of smaller ornamental trees, shrubs, and
fruit trees are chewed. The plant can actually be pulled out of
the soil very easily, or it may fall or lean over. Larger trees
and shrubs may have bark girdling on the roots or at the basal area
of the trunk which will cause decline and/or the death of the tree. Meadow
voles (Microtus pennsylvanicus) may also be a problem
in the home landscape and garden. The total length (head and body)
of the meadow vole is 3 1/2 - 5 inches. The tail is much longer
than that of the pine vole, and is one of the characteristics that
can be used to distinguish between the two species. The tail is
1 1/2 - 2 1/2 inches in length, and at least twice the length of
the hind foot. The fur of the adult is coarse and dark brown mixed
with black. Their eyes and ears are larger than those of pine voles,
but still much smaller than those of field mice (Peromyscus spp.).
Vole Management: Voles
require vegetation or other cover in order to survive. By eliminating
or reducing this cover one reduces their preferred foods, exposes
them to predators and exposes the animals to severe weather. In
home grounds, mulch around plants may serve as an excellent cover
for the voles. Deep mulch in gardens and plant beds should be reduced
and/or avoided where voles are known to be a problem. Certain mulches
are more likely to attract voles than others; avoid using mulches
with fine or small particle sizes. Large sized crushed-stone mulch
and pine bark mulch may reduce vole tunneling. Plastic and landscape
fabric mulches may increase vole populations and subsequent damage. Maintain
bare strips of soil under the drip line of trees and shrubs wherever
possible. Consider bare soil in gardens and plant beds where possible.
If mulch is used, keep it as far away from the trunks of plants
as possible. Frequent mowing of grass around trees and shrubs will
help to reduce the potential for vole injury. Tree
guards constructed from 1/4-inch mesh galvanized hardware cloth,
can prevent meadow voles from girdling trees. This will not work
for pine voles, however, which usually girdle roots. Guards should
allow enough room for 5 years of tree growth, and should be driven
several inches into the ground (without injuring tree roots.) Be
sure to overlap the hardware cloth where you tie it together and
do not leave cracks where voles can get in. Check these periodically
to be sure they are not restricting the growth of the trunk. Trapping
voles can provide additional population reductions. One trap which
is effective is the SHERMAN TRAP, * a box-type trap constructed
of aluminum and galvanized steel. Researchers have been able to
eliminate a high percentage (90+% in some research trials) of voles
per acre using these traps baited with apple pieces. The SHERMAN
TRAP used in research plots is model SNG and it's dimensions are
2 x 2.5 x 6 inches. Snap-back mouse traps baited with small apple pieces can be an economical alternative. Peanut butter can also be effective bait, but will attract more non-target mammals (i.e. shrews and field mice). Snap-back traps can be set above ground directly near vole entrances or in runways. Another method is to make an excavation across a tunnel and place a baited trap at the bottom of this excavation. Cover the exposed portion of the tunnel with a board, shingle, or other suitable material to exclude sunlight and prevent children and non-target animals from disturbing the traps. Trapping
is most successful when done in autumn (late October through November).
Trapping can also be effective in spring after snow cover has melted,
although winter vole damage has already occurred by this time. Trapping
during the summer may not prove as successful as there is plenty
of food available for voles at that time. It is also necessary to
pre-bait the location to be trapped at least 24 hours in advance
of trapping. This can be accomplished by placing apple pieces into
vole holes and tunnels. You will need to trap voles for at least
4 consecutive days to ensure good success. SHERMAN
TRAPS are set primarily above ground. Select sites near entrance
holes and in grass runways used by voles. Dig the soil away slightly
so the trap will lay on the bottom surface of the runway. Next,
cover the trap with an asphalt roofing shingle by draping it over
the trap to exclude sunlight. Voles are more likely to enter traps
covered in this manner and the shingle also keeps non-target animals
from disturbing the trap. Currently
the only rodenticides labeled for vole control in non-crop areas,
(i.e., lawns and ornamentals) are restricted-use pesticides. For
this reason they can only be purchased and used by a licensed, professional
pesticide applicator. * SHERMAN TRAPS are available from H.B. Sherman Traps, Inc., P.O. Box 20267, Tallahassee, Florida, 32316. Telephone (850) 575-8727. FAX (850) 575-4864. At this time the company is not supplying retail stores. You can order directly from the company. If possible try to have a local garden supply or hardware store order a quantity of the traps for you and your neighbors. This could be a more economical way to purchase the traps. Note: The use of dried blood or fox or coyote urine has also been effective in repelling these animal pests. Follow directions carefully with the predator urine. Some formulations may need to be reapplied after a rain.
Adapted from Thomas Kowalsick, Cornell University, 2001
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