A faint scratching sound under the ground, a burrow opening beside the wall, and a torn garbage bag: these are the signs of the Norway rat (Rattus norvegicus), the most widespread rat in the world and the one most associated with sewers and ground floors.
This article is part of the rodent library alongside the article on Rats and Rodents, and here we detail what is specific to the Norway rat.
Size: the largest of the household rats, reaching about 40 cm including the tail, with a heavy body, a blunt pointed nose and a tail shorter than its body.
Place: it digs burrows underground and beside foundations and sewers, and prefers lower floors and damp places.
Food: it eats almost everything from waste to grain and scraps, and it needs water daily, so it stays close to a source.
Breeding: it breeds quickly in several litters a year, so a small infestation left alone becomes an adult colony.
The rule: locked bait stations at burrows and runways with sealed entry points and removal of food, as part of a continuing plan, not a single spray.
How do you recognize it?
Its shape is the first thing that tells it apart from others:
- Size: a heavy body about twenty to twenty-five centimeters long and weighing between 250 and 500 grams.
- Face: a slightly pointed nose and small ears close to the head.
- Tail: shorter than the body, thick and rough.
- Color: brown with gray and a lighter belly.
- Droppings: about one and a half centimeters long, capsule-shaped with rounded ends.
Where does it live?
It prefers to stay close to the ground and water, and it digs tunnels.
- Burrows: around foundations, walls and sidewalks, and under piles and lumber.
- Sewers: drainage channels and basements.
- Food sites: garbage, restaurants, storerooms and animal waste.
- Inside: the ground floor, basements and under floors more than upper floors.
How does it feed and breed?
It eats almost everything, and prefers grain, meat and cooked food. The female gives birth several times a year.
- Quantity: it eats roughly an ounce of food a day and contaminates more.
- Breeding: a female may give birth to five to twelve young in one litter, several times a year.
- Caution: it avoids new objects, which is why it may ignore a new trap for days.
The recommended plan
- Inspection: look for burrows, droppings and greasy runways on walls.
- Bait in stations: locked stations beside walls and along travel paths.
- Traps: strong ones of a suitable size for large rats near burrows.
- Closing burrows: after making sure they are empty of rats.
- Cleanup: remove food and shelter sources from the outside.
For details, see getting rid of rats and mice and preventing them.
Why is it one of the hardest rodents to control?
- Intelligence and caution: it avoids new objects and watches for sources of danger.
- Rapid breeding: a female may give birth up to seven times a year.
- Adaptability: it lives in sewers, buildings and farms.
- Swimming and digging: it swims and digs long tunnels.
Mistakes that make its presence easier
- Open garbage bags: near the back door.
- Piles of lumber and scrap: ready-made shelters.
- Exposed sewers: or drainage grates without a cover.
- Storing grain in bags: without closed bins.
Its daily /h2>
The Norway rat is mainly nocturnal, so an infestation may go on for weeks before you see a single rat. It comes out after sunset and moves along walls and edges because its whiskers help it sense the space, and it usually does not go far from its burrow as long as food is near. Over time fixed runways form that it uses every night, so dark greasy marks appear on walls at corners from its fur rubbing, and trampled paths appear through grass and gravel.
It needs water daily, so you find it near leaks, drainage channels and small pools. If you find burrows around foundations with a water source next to them, know that the place has become a suitable shelter for it.
How do you confirm it is the Norway rat and not another?
Confusion between the Norway rat and the roof rat is common, and the difference matters because it decides where you place stations and traps:
- Infestation location: burrows, ground runways, basements and areas near sewers point to the Norway rat, while sounds in the ceiling and trees point to the roof rat.
- Dropping shape: large and capsule-shaped with rounded ends for the Norway rat, and smaller and pointed for the roof rat.
- Burrows: roughly round openings several centimeters across beside walls and foundations, and the ground around them is often packed down and bare of plants.
- Damage: it gnaws wood, bags and plastic pipes near the ground, and digs under weak concrete.
What attracts it to your home or farm?
A rat does not come by chance; it stays where it finds three things together: food, shelter and water. The most common things we notice in practice:
- Garbage bags left outside the bin or bins that are not closed.
- Leftover pet food and bird feed scattered on the ground.
- A pipe leak or standing water near walls.
- Piles of lumber, stones and old furniture left in the yard.
- Floor cracks and openings around drain pipes and cables.
Why do scattered solutions fail?
The mistakes we see repeated: placing exposed bait anywhere without a station, putting down one trap and waiting, or sealing a burrow while it is still occupied so the rat digs another exit. A rat may also ignore new bait for days because it avoids anything strange, and if you change the station location every day it will never get used to it. The most successful solution is keeping stations in place and choosing their locations well, while removing alternative food so the rat accepts the bait provided.
When should you call a specialist?
If you find multiple burrows, an infestation near a public sewer, or see rats in the daytime, or the infestation is in a restaurant, storeroom or large farm, it is best to have a pest control specialist inspect the site. They identify the runways, place stations according to the size of the colony and follow up periodically, which is more economical than trying scattered solutions that prolong the infestation.
Products from the Orkida store
We prefer locked stations and a plan that combines bait, traps and sealing entry points. We also advise following the dose on the package and placing bait away from children and pets.
- ProCatch Bait Station for Rats and Mice | English-made BULLET Model: a locked, tamper-resistant bait station in which we place the bait away from children and pets, suited to rats and mice along walls and passages.
- ProCatch Medium Bait Station for Rats and Mice | English-made Rascal Model: a medium-sized station for larger rats and outdoor entrances.
- ProCatch Large Bait Station for Rats and Mice | English-made Vanguard Model: a large station for farms, storerooms and open areas where rodents gather in large numbers.
- Ruban Soft Bait for Rats and Mice, 250 g: a wrapped soft bait that attracts mice and is easy to place inside stations, from a specialized international company.
- Rozol Soft Bait for Rodents, 200 g: a soft bait from the international Liphatech, favored by rats and mice and used in stations.
- Catchmaster American Ready-to-Use Glue Traps for Mice and Crawling Insects | 72 Glue Boards: glue traps for monitoring and light infestations, useful indoors where bait is not wanted.
Frequently asked questions
How do I tell the Norway rat from the roof rat?
The Norway rat is heavier, with small ears and a tail shorter than its body, and it digs. The roof rat is slimmer, with large ears and a longer tail, and it climbs.
Does it enter homes?
Yes, through cracks and drain openings, especially on the ground floor and in basements.
Does it cause diseases?
It carries bacteria that can spread through urine and droppings; see rodent damage and diseases.
Why does it not touch the bait?
It avoids anything new, so leave the station empty for a few days and then add the bait.
How long does the Norway rat live?
In the wild it usually lives about one to two years, but it breeds quickly and makes up for any loss fast if food and shelter remain.
Does it bite people?
It usually runs away, but it may bite if cornered or sick. Wash any bite with soap and water and see a doctor.