Pests from A to Z
Rodents
Mice
The House Mouse, and sometimes the Long-Tailed Field Mouse, seek the warmth and shelter of buildings for nesting sites and food. Their presence is usually detected from their dark-coloured droppings or damage to stored foods in the larder, packaging or woodwork.
Mice become sexually mature in eight to ten weeks, and a pair may produce eight litters, each of 16 young, in a year. Multiply those and you arrive at a horrifying number of mice! They climb well and can squeeze through very small gaps.
These nibbling nuisances have a compulsive need to gnaw in order to keep their incisor teeth worn down to a constant length. Electric cables, water and gas pipes, packaging and woodwork may all be seriously damaged by mice – many instances of electrical fires and floods have been attributed to them. They contaminate far more food than they consume and they are capable of carrying many diseases, particularly food poisoning. The average mouse deposits 70 droppings in 24 hours and urinates frequently to mark its territory.
Mice are erratic, sporadic feeders, nibbling at many sources of food rather than taking repeated meals from any one item. They do not need free water to drink as they normally obtain sufficient moisture from their food.
Field Mice
Outdoor cousins of the House Mouse, which tend to move indoors in the winter seeking their creature comforts. The Wood Mouse or Long-Tailed Field Mouse has larger ears, more prominent eyes and a longer tail than the House Mouse and is brownish with a white underside. Fond of apples and stored food.
House Mouse
The grey House Mouse with big ears, long whiskers and long, hairless tail is a major pest.
Long Tailed Field Mouse
See Field Mice
Super-Mice
A favourite media term. These rodents are generally described as resistant to all known poisons, larger, more voracious and generally more intelligent than their controllable relatives.
In reality, tolerance of some anti-coagulant rodenticides does exist in both rats and mice but does not, as yet, present a serious problem in control.
Rats
The rat has plagued humans for thousands of years – the rat flea was responsible for the Black Death. There are two species of rat in Britain, Rattus norvegicus which is commonly known as the Brown Rat and Rattus rattus which has the common names Black Rat or Ship Rat.
The Brown Rat is the larger, often weighing over half a kilo and measuring about 23cm, without counting the tail. It has a blunt muzzle, small hair-covered ears and a tail that is shorter than its body length. The Black Rat weighs only half as much and is slightly shorter. It has a pointed muzzle, large, almost hairless ears, a more slender body and a long thin tail that is longer than its body.
Both species breed rapidly and become sexually mature in about three months. Each female may produce from three to 12 litters of between six and eight young in a year.
Rats, like mice, need to gnaw to keep their constantly growing incisor teeth worn down. They damage woodwork, plastic and lead pipes and will sometimes strip insulation from electrical cables by their gnawing.
Rats will hoard food for future consumption and numerous cases of “theft” have been found to be the work of rats. They feed mostly at night and an average rat will eat 50g of food a day.
Creatures of habit, rats leave regular “runs” to and from feeding areas. They can be a menace to poultry, eating eggs, chicks and animal feed.
They are also capable of spreading many diseases from their filthy surroundings in sewers or refuse tips and can transmit food poisoning, Weil’s disease (from which about ten people and a number of dogs die each year in the UK), murine typhus, rat bite fever, trichinosis and other diseases. They are probable carriers of foot and mouth disease on farms. They contaminate more food than they consume and their urine can pollute stagnant water.
Black Rat
The old English ship rat or roof rat that brought the Black Death across Europe in the 14th century and the Great Plague of London in the 17th century. They are still occasionally to be found in seaport towns but have mostly been ousted by their voracious big cousin, the larger Brown Rat from central Europe.
The Black Rat still occurs in seaport towns and is a more agile climber, often entering the upper floors of buildings. It is possible to identify the species present from the different shaped droppings, footprints in dust (the Brown Rat is flat footed, the Black Rat runs on its toes) and presence of tail swipes. In towns, Brown Rats often live in sewers but in the countryside there is a constant background population in fields and hedges.
Brown Rat
The Brown Rat is the commoner species and stays near ground level. The common or Norway rat, also known as the sewer rat. May weigh half a kilogram and measure 23cm long, exclusive of its tail. Colour varies from brown to black but this species is distinguished from the true Black Rat by its small size, small blunt muzzle and its tail being shorter than its body length.
Brown rats will burrow underground or into suitably soft material to make a nest. Refuse tips, loose soil under sheds and earth banks are all likely sites and chewed paper, straw or insulation material may be incorporated as nest material. The young are born blind, helpless and naked and depend on their mother for food for about three weeks before they are sufficiently developed to take solid food.
Squirrels
Deliberately introduced to this country sometime in the 19th century the grey squirrel has since spread throughout most of mainland England and Wales. Mainly a resident of broadleaved and mixed woodlands it is also a common resident of urban parks and gardens.
They frequently enter domestic roof spaces. Once inside they chew woodwork, strip insulation from electrical wiring and water pipes, tear up fibreglass insulation and, occasionally, drown in water tanks.
Voles
Small, blunt-nosed rodents which occasionally enter buildings, but which normally live in outdoor burrows. Not regarded as a household pest, the water vole is a protected species.
