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University
of Rhode Island GreenShare Factsheets
Meadow
and Pine Voles
Significant populations of either meadow voles, Microtus
pennsylvanicus, or pine voles, Microtus pinetorum, occasionally
invade home lawns. Plant injury from vole feeding can be
severe enough to cause significant decline and/or death of
ornamental or garden plants.
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.).
Meadow voles live primarily above ground or in shallow surface tunnels or runways.
These runways can sometimes be observed in lawns or in snow cover. Nests made
of interwoven strands of dry grass are baseball-sized food caches. The females
maintain exclusive territories during the breeding season, while the males
are mobile.
Meadow voles are listed as feeding on grasses, sedges, seeds, grain, bark and
some insect parts. These voles will feed on the bark of trees girdling the
trunks at or near the ground surface. The girdling may be higher in the winter
months if snow cover exists. Sometimes roots may be damaged.
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
Pesticides
are poisonous! Read and follow all safety precautions on labels.
Handle carefully and store in original containers out of reach
of children, pets or livestock. Dispose of empty containers
immediately, in a safe manner and place. Pesticides should never
be stored with foods or in areas where people eat.
When trade names are used for identification, no product endorsement
is implied, nor is discrimination intended against similar materials.
Be sure that the pesticide you intend to use is registered for
the state of use.
The user of this information assumes all risk for personal injury
or property damage.
For more
information, call the URI CE Gardening and Food Safety Hotline
at 1-800-448-1011 or (401)874-2929 from outside Rhode Island;
Monday-Thursday between 9 am and 2 pm.
University
of Rhode Island Cooperative Extension provides equal program
opportunities.
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