The Norway rat, also known as the grey rat or sewer rat, measures about 46 cm from the tip of its snout to the tip of its tail.Its body is massive and robust. Its tail is hairless and covered with scales.It is shorter than the rest of the body.Its coat is gray-brown and becomes paler on the ventral part.On the head, 2 small ears close together seem to be half buried in the fur.The eyes are small and the muzzle is square.

Latin Name: Rattus norvegicus

Description :

The Norway rat, also known as the gray rat or sewer rat, measures about 46 cm from the tip of the snout to the tip of the tail.
His body is massive and robust. Its tail is hairless and covered with scales.
It is shorter than the rest of the body.
His coat is gray-brown and becomes paler on the ventral part,
On the head, 2 small ears close together seem to be half buried in the fur.
The eyes are small and the muzzle is square.
In addition, it would not distinguish colors.
The rat’s excrements allow to identify it.
They are cylindrical and measure an average of 19 mm in length and 6 mm in width.
Note that in the wild, we meet the common muskrat, much larger
(48 to 64 cm), associated with wetlands, as well as the hairy-tailed mole and the star-nosed condylure, which dig tunnels in the ground.
These species do not belong to the family Muridae, which includes rats and the common mouse.


Mating occurs mostly in the spring and fall. The spleen can produce 3 to 12 litters per year, each with an average of 7 to 8 young. Not all of them survive, and the female only weans 12 to 56 per year.
They are born hairless and with their eyes closed.
The spleen may mate again a day or two, or even a few hours, after the young are born.
They learn to favor or distrust certain foods by tasting the mother’s milk and watching the female.
They quickly become independent and reach maturity at about three months.
The average lifespan of the Norway rat is 12 months.


To find its food, it can climb, jump (at least 0.9 meters vertically), swim and chew wood, asphalt, plastic, lead, aluminum or copper.
His search for food and water would be carried out within a radius of 30 to 45 meters, and he would rarely stray more than 100 meters from his burrow.
It consumes about 15 to 30 g of a variety of foods (vegetables, fruits, cheese, meat) daily, and when given a choice, it prefers grains.
The rat often eats its fellows when the rat population density is high. In the wild, their diet includes insects, birds, fish, lambs and piglets, as well as the feces of other animals, which they dissect for undigested food particles.
It seeks out a water source and drinks 29-59 ml each day, or less if its food contains water, and will settle for human urine if it has no other choice.
The rat usually takes the same route it explores to memorize each object, as it fears novelty.
These trails usually run along walls and pipes, or through piles of goods where it can easily hide.
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.
In the interior of buildings, it makes its home in walls, between ceilings and floors, and
anywhere trash accumulates. It lives in colonies of several individuals subject to a social hierarchy
The Norway rat is a pest that causes considerable damage to structures and equipment by gnawing on them. It also contaminates food with its feces and spreads various diseases transmissible to humans, such as
yellow fever, rabies, dysentery, as well as parasites such as lice, fleas and mites.


Rats do not actually nest in sewers, but they do move around and collect food. Their presence in the house may be due to inadequate or defective plumbing or a broken sewer connection caused by an excavation or by tree roots that fit into a small opening. Outside, near walls, niches or feeders, we can sometimes notice holes (7.5 cm in diameter) leading to their tunnel, but these are often hidden by debris.
To prevent their introduction, all openings larger than 1.3 cm should be plugged with materials such as mortar or galvanized metal sheets.
However, even if they are prevented from entering a building, their numbers will not decrease if they can dig into the earth for shelter and if they have access to a food source.
The use of sturdy containers to store food and careful management of waste and debris will reduce the amount of food and shelter available.
It is best not to put garbage outside too soon.
They should definitely not be fed.
Another way to ensure that pet food is not available to rats and that they do not have easy access to a water source is to repair leaky faucets, for example.
If food and shelter are not reduced, the population may increase again even after killing rats because rats will have more pups per litter and the pups will survive more.
Surrounding weeds and debris should also be removed to reduce the number of potential shelters.
Rats can damage buildings or pipes, dig under foundations in ways that weaken them, transmit or be vectors, via fleas and mites, of pathogens including salmonella, or bite young children.
The damage they cause to electrical wires can also cause fires. Their presence should not be tolerated.
With their urine and feces (20 to 50 per day), rats contaminate ten times more food than they consume.

For all these reasons, don’t hesitate to contact a plumber to repair leaky pipes, a contractor to plug openings in the building, and a pest management specialist to apply treatments to control any infestation.

We also treat all other pest problems (wasps, carpenter ants, cockroaches, bed bugs, white worms etc)

To learn more about these parasites, visit our Encyclopedia of Parasites