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Latin name: Rattus norvegicus

Description :

The Norway rat, also called gray rat or sewer rat, can measure about 46 cm from tip of nose to tip of tail.

His body is solid and robust. Its tail is hairless and covered with scales.
The tail is shorter than the rest of the body.
Its coat is gray-brown and becomes lighter on the ventral section,
On the head,the two small ears seem half buried in the fur.
The eyes are small and the muzzle is square shaped.
Apparently, its color blind.

We can identify it by its feces.
They are cylindrical and measure an average of 19 mm long and 6 mm wide.


Mating especially in spring and fall. It can generate 3 to 12 litters each year comprising 7-8 young on average. They will not all survive, usually no more than 12-56 per year make it.
They are born hairless and their eyes are closed.
The female can mate again a day or two or even a few hours after giving birth.
The young learn about safe food sources by tasting their mother’s milk and by watching her.
They quickly become independent and reach maturity at three months.
The average lifetime of the Norway rat is 12 months.


To find food, it can climb, jump (at least 0.9 m. vertically), swim and eat away at wood, asphalt, plastics, lead, aluminum or copper.
His search for food and water is carried out within 30 to 45 meters from its nest, and it rarely moves away to more than 100 meters from its burrow.
It consumes about 15 to 30 g of varied food (vegetables, fruit, cheese, meat) daily and, when given the choice, he favors cereals.
Rats often eat their fellow rats when the population density is high. In nature, its diet includes, among others, insects, birds, fish, lambs and piglets, he can also dissect through other animal feces to remove undigested food particles.
He seeks a source of water and drinks 29 to 59 ml daily, or less if their food sources contain a lot of water. It can even drink human urine if he has no choice.
The rat usually follows the same route he used to explore because he fears all that’s new.
These tracks usually follow the walls and pipes, or will go through piles of rubble where it can hide easily.

It begins its activities at dusk and continues until the middle of the night.
When food is scarce, it may also be active during the day.

Inside buildings, he prefers to use spaces inside the walls or under floors or ceilings.

He lives in colonies of several individuals subject to social hierarchy

The Norway rat is a parasite that causes considerable damage to structures and equipment by gnawing.

It also contaminates food through its feces and can spread various diseases transmissible to man, such as yellow fever
, rabies, dysentery, as well as parasites such as lice, fleas and mites.


Rats do not actually nest in the sewers, but they circulate and collect food there. Their presence in the house is usually from a non-adequate or defective plumbing section or a broken sewer line ( sometimes caused by excavation or tree roots breaking drainpipes).

Several signs may reveal the presence of rats: their noise, teeth marks (3.5 to 4 mm wide) or entry hole of at least 5 cm in diameter.

Outside buildings, near walls, doghouses or feeders, you will notice holes (7.5 cm diameter) leading to their tunnels, but they are often hidden by debris.

To prevent their introduction, you must plug all openings of more than 1.3 cm using materials such as mortar or galvanized sheet metal.
However, even if they are prevented from entering a building, their numbers will not decrease as long if they can dig for shelter and they have access to a food source.
Using sturdy containers to store food and a strict management of waste and debris will reduce the amount of food and shelter available for them.
It is best not to take the garbage out too early.
It is important not to feed them.
Also make sure that pet food is not accessible and they do not have easy access to a water source by repairing, for example, leaky faucets or broken pipes.

If food and shelter are not reduced, the population can grow again even after killing a lot because they will increase their breeding rate and they will insure their survival.

Weeds and surrounding debris around buildings should be removed to reduce the number of potential shelters.

Rats can damage buildings or pipes, digging under the foundations to weaken them and create openings.

They transmit diseases via fleas and mites, or pathogens including salmonella with their urine.
The damage they cause to electrical wires can also cause fires. So their presence can’t be tolerated.

With their urine and feces (they produce from 20 to 50 per day), rats contaminate ten times more food than they consume.

For all these reasons, do not hesitate to contact a plumber to fix leaky pipes, a contractor to block the openings in the building and a specialist in pest management to apply treatments to control infestation.


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