Norway Rat (aka Brown Rat, Sewer Rat, Street Rat)

Scientific name: Rattus Norvegicus


The brown rat, also referred to as Common Rat, Street Rat, Sewer Rat, Hanover Rat, Norway Rat, Brown Norway Rat, Norwegian Rat, or Wharf Rat (Rattus Norvegicus) is one of the best known and most common rats.

It is a brownish or reddish grey above and whitish grey on the belly. This rodent with a body up to 25 cm (10 in) long, with a tail shorter than the head and body; the male weighs on average 350 g (12 oz) and the female 250 g (9 oz). Thought to have originated in northern China, this rodent has now spread to all continents except Antarctica, and is the dominant rat in Europe and much of North America—making it the most successful mammal on the planet after humans.

It has a blunt nose, small ears and a thicker body when compared to the roof rat (aka black rat) (Rattus rattus).


The brown rat is a true omnivore and will consume almost anything, but cereals form a substantial part of its diet. Studies had conclude that the most-liked foods of brown rats include scrambled eggs, macaroni and cheese, raw carrots, and cooked corn kernels. They will eat around 30g of food and drink 60ml of water a day.


They live in and around residences, in cellars, warehouses, stores, slaughterhouses, docks, and in drainages and sewers. They may burrow to make nests under buildings and other structures, beneath concrete slabs, along stream banks, around ponds, in garbage dumps, and at other locations where suitable food, water, and shelter are present. Although they can climb, most tend to inhabit the lower floors.

This rat is nocturnal and is a good swimmer, both on the surface and underwater, and has been observed climbing slim round metal poles several feet to reach garden bird feeders. Brown rats dig well, and often excavate extensive burrow systems

They cause structural damage to buildings by burrowing and gnawing. They undermine building foundations and slabs, cause settling in roads and railroad track beds, and damage the banks of irrigation canals and drainages. Rats also may gnaw on electrical wires or water pipes, either in structures or below ground. They damage structures further by gnawing openings through doors, window sills, walls, ceilings, and floors.

Considerable damage to insulated structures can occur as a result of rat burrowing and nesting in walls and attics.


The brown rat can breed throughout the year if conditions are suitable, with a female producing up to five litters a year. The gestation period is only 21 days, and litters can number up to 14, although seven is common. They reach sexual maturity in about five weeks.

Under ideal conditions (for the rat), this means that the population of females could increase by a factor of three and a half (half a litter of 7) in 8 weeks (5 weeks for sexual maturity and 3 weeks of gestation), corresponding to a population growing by a factor of 10 in just 15 weeks. The maximum life span is three years, although most barely manage one.

Diseases and Risks

Among the diseases rats may transmit to humans or livestock are Leptospirosis, Murine Typhus, Trichinosis, Salmonellosis (food poisoning), and rat bite fever. Plague is a disease that can be carried by a variety of rodents, but it is more commonly associated with roof rats (Rattus rattus) than with Norway rats.


Jaya Pest Solutions encourages people to dispose rubbish properly, seal off all/any cracks and crevices around the drainages and perimeter of the house, have a proper covered rubbish bin, not leave any exposed food overnight and regularly cleaning of the drainage and waste disposal areas. To effectively manage a serious rats infestation, you must correctly identify the type of rats causing the infestation and the able to diagnose the core problem, which is why it is important to contact a pest control professional.


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