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There are two species of rat here in Britain, the brown rat (Rattus Norvegicus) and the black rat (Rattus Rattus).

Brown rats

The brown rat is one of the best known and most common rats. It is primarily nocturnal, although someBrown Rat (Rattus norvegicus) individuals can be seen during the day in highly populated areas.

Their diet is extremely broad and they will eat almost anything that is edible. Although brown rats do not carry bubonic plague, they do harbour an array of other diseases such as Weils disease and Salmonella.

The brown rat is the larger of the two, often weighing over half a kilo and measuring about 23cm, without counting the tail. The black rat weighs only half as much and is slightly shorter.

The brown rat is the more common species and stays near ground level. Brown rats often live in sewers in towns, but in the countryside there is a constant background population in fields and hedges.

Lifecycle of the brown rat

The brown rat can breed throughout the year if conditions are suitable, with a female rat producing up to five litters per year. The gestation period is only 21 days and litters can number up to 14.

Black rats

The black rat is nocturnal and omnivorous, with a preference for grains and fruit. Compared to the brown rat, it is a poor swimmer but is more agile and a better climber.

A typical adult black rat is 32-45cm long including tail and weighs approximately 110-340g. It is usually black to light brown in colour with a lighter underside.

The average lifecycle of a black rat is 12-18 months, during which the female will breed up to 6 times with the average litter being 7 young.

Black rats nest both indoors and out, preferring high places such as trees and loft spaces.


Rats can enter a building through a gap as small as half an inch in diameter. They are strong swimmers and will live in sewers, entering buildings through broken drains or toilets. Rats will climb in order to access food, water or shelter. Rats will always follow standard routines and pathways. If new objects are placed in its path, they will painstakingly avoid it. They tend to stay 300 feet of their nest or burrow.

Rat Facts

  • Signs of a rat presence include droppings, smear marks, gnawing, tracks, runways and burrows.
  • Rats can be distinguished from mice by physical characteristics, primarily their larger size.
  • Rats have poor eyesight but have a very strong sense of smell, taste and hearing.
  • The 2 dominant rat species in the UK are the Brown Rat and the Black Rat. The Brown Rat is the commoner species and stays near ground level. 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.

The Solution - Control techniques

Control techniques should be designed to eliminate the infestation completely, since any remaining rodents will produce a rapid re-infestation. Control techniques can be chemical and non-chemical. Non-chemical techniques may be used on their own, such as the utilisation of live traps, glue boards and traditional back breakers but more often these methods are used to complement chemical control. Some additional non-chemical techniques such as ultrasound have not been proven to be as effective as long-term control measures.

The use of rodenticide contact dusts, gels, baits and traps will, when used professionally control an ongoing rodent infestation. AG Pest Management's staff has many years experience in eradicating rodent infestations successfully. Contact us on 01226 288844.

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