Scientific names Apodemus, Myodes and Microtus species
Plants affected Many, including pea seedlings, apple and strawberry fruits, crocus corms
Main causes Mice and voles eat the foliage, seeds and fruits of many plants, and also gnaw bark from woody plants
Timing All year round
What are mice and voles?
Mice and voles are a natural part of the animal life that gardens support. There are four species that can be found in British gardens and sometimes cause damage, in most cases this is minor and can be tolerate. These are
.the wood mouse, Apodemus sylvestris, the short-tailed vole, Microtus agrestis, and the bank vole, Myodes glareolus. The yellow-necked field mouse, Apodemus flavicollis, mainly occurs in southern England and Wales. These mainly nocturnal small rodents are active all year round. Most of the time the population levels are relatively low and little plant damage is noticed but mice and voles can reproduce rapidly under good conditions, leading to population explosions and damage to plants.
Mice differ from voles in having tails that are longer than their bodies. The head of a vole, when viewed from the side, has a rounded appearance, whereas a mouse's head is extended forwards. Both mice and voles can feed on a wide range of plants.
Paired grooves may be seen on stems, crocus corms and stored apples, where the rodents' incisor teeth have gnawed at the food item. Holes may be seen in the soil where mice or voles have dug down to feed on bulbs, corms or germinating seeds. Remnants of seedlings may be scattered on the soil surface. Field mice sometimes bite off strawberry and other fruits before they are ripe and leave the berries in small heaps among the plants. Soft areas in a lawn with small heaps of soil on the surface are likely to be due to voles (as opposed to moles) tunnelling just beneath the surface.
Mice and voles can eat the recently sown seeds of peas, beans and sweet corn and kill seedling plants by grazing on the foliage. In cold weather field mice often enter greenhouses and cold frames, where they can destroy many seedlings overnight. They can also enter sheds and feed on stored fruits, such as apples.
Voles sometimes eat the bark of a wide range of woody plants, particularly in winter when vegetation is frozen and less palatable. If bark is lost from all or most of the circumference of a stem, then growth beyond that point dies. On evergreen plants, such as yew and ivy, the dieback may not be noticeable until later in the spring or summer.
Voles make a network of shallow tunnels in the soil and this can give lawns an uneven and soft surface.
Crocus corms and tulip bulbs are often eaten, especially in the first autumn-winter after planting. Established bulbs and corms are less susceptible.
Prevention and control
Mice and voles are normally present at low numbers in gardens and can be treated as part of the biodiversity that gardens support. Small rodents can feed on invertebrates such as snails and they themselves fall prey to larger animals including owls.
At times when mice or vole populations are high and causing intolerable damage it can be difficult to make much impression on their numbers. Fortunately these rodents do not sustain high populations for long and their numbers will drop back to normal low levels.
Fitting young or newly planted trees with tree spirals (biodegradable spirals based on potato starch are available) can help reduce damage to bark.
Where possible tolerate or use barriers and contained storage to deter damage from these animals as all methods of control involve killing them. RSPCA advice on living with mice can be found here
Trapping is available for use in a garden situation although should be avoided as this either kills the animals or live traps can cause unnecessary suffering. Break-back traps used out of doors must be placed under covers to reduce the risk of other animals interfering with them. Birds are particularly vulnerable to accidental trapping, which is prohibited.
Non-lethal traps are available but these must be checked at least twice a day, to comply with animal welfare legislation, and the rodent released some distance (several miles is usually recommended) from the trapping site. These animals suffer high levels of stress in the traps, during transportation and survival rates once released are unknown.
Accidental poisoning of non-target animals is illegal. Although available for control of some rodents the use of poison baits should be avoided. It is recommended that if this option is considered The Campaign for Responsible Rodenticide Use (CRRU) code for best practice is followed.
Mice and voles remain active all year round. The breeding season is between spring and autumn, when field mice and voles can produce up to five litters of four to six young. The young are born underground in nests made of dry grass. These rodents are heavily predated by cats, foxes, stoats, weasels, owls and other birds of prey.
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