In huts, sheds and barns, the presence of bank voles can be detected by sounds, droppings, marks caused by gnawing and urine odours.
Just like other rodents, bank voles destroy foodstuff, by consumption, as they eat and by contamination with saliva, urine, droppings and hair. They cause more damage by gnawing materials like paper, cardboard, insulation, packaging, textiles, cables, pipes and wood, for reasons such as opening food containers, gathering nest-building material, making access holes wider, or simply to grind down their incisor teeth.
A roll of Styrofoam, stored in a barn, damaged by bank voles
In their natural environment the presence of bank voles is evidenced by holes in the ground, by their runways in the ground-covering layers of vegetation and by debarked tree branches.
Often, when a human observer remains quiet and still near a burrow, bank voles will emerge, but they will stay exposed only very briefly and will rush back into hiding at great speed.
Bank voles damage saplings and young trees by feeding on the bark of elder, beech, larch and Douglas fir trees. In years of high population density, they may cause serious reductions in reforestation and inhibit the natural regeneration of woodland. They are, therefore, regarded as plant pests.
Bank voles can be harmful to health. They harbour pathogens and parasites and bring them into human residences. Bank voles carry fleas, ticks, mites and tapeworms. Transmission of pathogens occurs by contact with the rodents’ faeces, urine, saliva, blood and hair.
Fleas leaving a bank vole that has been killed with a mouse trap.
Bank voles are the main carrier of the Puumala-Hanta virus, which causes severe haemorrhagic fever and kidney failure. The virus is transmitted by contact with an infected bank vole’s body fluids, fur or faeces. The excretions are contagious up to 12 days. Infection is also possible by inhalation of contaminated dust. This may happen when cleaning up an infested area or handling piled up firewood. The number of Hanta infections in humans correlates with the number of bank voles and every 3-4 years, when a year of high-density population occurs, there is a peak the infection rate.
Bank voles are intermediate hosts for the fox tapeworm. Humans can be infected with this worm by direct contact with bank voles, or, indirectly, via cats or dogs that have eaten bank voles. Infections with fox tapeworm are rare but disastrous. This worm ends up in the lungs, brain or liver of humans and can be fatal. There exists a treatment using powerful drugs to stop the progressive destruction of organs, but there is no cure. The drugs must be taken for life.
When catching bank voles or working in infested areas, gloves and a FFP3 mask should be worn.
The droppings of bank voles are a bit thicker than house mouse droppings: they are black, 3-6mm long, black, with rounded ends. An adult typically produces 50 to 75 pellets per day and even a small infestation of bank voles can produce thousands of droppings in a short time.
Bank voles gnaw various materials. The marks caused by gnawing and the shredded materials are additional evidence for the presence of bank voles. The width of the teeth marks can distinguish bank voles from rats: a bank vole’s tooth is 0.5mm wide and a rat’s tooth 2-3mm.
Outdoors, signs of gnawing can be found on the debarked branches of elder, beech, larch and Douglas fir trees.
When bank voles are active, they make noises by gnawing or by running around in empty spaces in ceilings or walls. Outdoors, one may hear a rustling in the ground-covering vegetation when bank voles are moving around.
Bank voles continuously lose urine as they walk about. The smell helps them orientate themselves in the dark. With a substantial or long-lasting infestation, a strong smell of urine will be detected. Cat and dog owners may see their pets excitedly sniffing, probing and scratching places where bank voles have been.
Bank vole populations increase in conditions that allow easy access to abundant food and good protective shelter. These should be avoided.
The best time to act against bank voles is in autumn when crops have been harvested and the cold, wet weather sets in. Voles leave their summer quarters and look for dry and warm winter-shelter in and on buildings. It is best to catch or drive the voles away before they become ensconced in buildings. Bank voles need an opening of only 6mm diameter to gain entry so there are often many access points around the perimeter of a building. Bank voles penetrate mainly through open or poorly closing doors and gates, and through basement windows, lighting shafts, pipe ducts, cable ducts, cooling and ventilation systems, outdoor lights, transformer stations, switch boxes and other apertures in outer walls. If possible, access points should be sealed to prevent future infestations. SWISSINNO Rodent Stop Steel Wool is a quick and easy fix to plug wall openings, holes and cracks.
Wood mice are excellent climbers. Planted facades, wood cladding and insulation offer ideal climbing aids.
Eliminate nesting possibilities to discourage bank voles from colonising the site. Get rid of piles of wood stacked against house walls, and of bulky rubbish on the site, and of dense ground-covering vegetation to make the area unattractive for nesting.
Remove all food sources and avoid excessive bird feeding. Store foodstuffs, pet food and seeds in rodent-proof containers and not in bags or boxes.
Remedies: outdoors, agriculture, forestry
Ultrasonic Rodent Repellents are an effective method of scaring bank voles away and preventing them from entering buildings. High-pitched frequency sound waves emit a non-repetitive pattern to prevent rodents from habituating to the sound.
It is important to note that ultrasonic frequencies do not travel through walls, so at least one repellermust be placed in each room.
Ultrasonic repellers are not completely effective on their own. For maximum control they should be incorporated into an integrated pest management strategy comprising mechanical traps with food deprivation, sanitation and the closure of access routes.
There are no special traps for bank voles, but conventional mousetraps work perfectly well. Traps are an effective method of non-toxic and humane mouse control. There are 3 types of mouse traps commonly used for rodent control: Snap Traps, Catch Alive Traps, and Electronic Traps.
The following table gives an overview of the different SWISSINNO mousetraps:
A SWISSINNO mousetrap provides a quick and easy solution to a rodent control problem and it can be used many times over. A big advantage of using a mousetrap is that it retains the animal’s carcass so that the ‘trapper’ can dispose of it safely. Death by poison is never instantaneous so the animal may leave the scene and die out of sight in an inaccessible place like behind the skirting boards or under the floor boards where it will decompose emitting noxious odours and attracting flies, maggots and other insects into the home.
Bank voles and common voles are not trap-shy. Trapping follows the same procedure and uses the same SWISSINNO baits as for trapping house mice and wood mice.
Mouse trapping: How to go about it:
It is better to fight mice with traps. SWISSINNO advises against the use of poison bait for several reasons: