norway rat on cardboard box

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There are two rat species that are common pests in Pittsburgh. One is called the common rat and the other is called a house rat. Do you know which is a Norway rat? There is a lot you can tell about a pest by what it is generally named. The Norway rats is often called a common rat because it is very common. It is not, however, called a common house rat. Norway rats prefer to establish their nests in burrows under the ground, not in the attic spaces of homes, like house rats do.

What Is In a Name?

House Rat — The common house rat is Rattus rattus, also known as a roof rat or ship rat. These two names describe two qualities of house rats. They prefer to nest in high places and they commonly get into man-made structures, including ships. This is exactly what you would expect from a house rat.

Common Rat — These rats, which are known scientifically as Rattus norvegicus, go by many names. They are called sewer rats, wharf rats, water rats, Norway rats, street rats, fancy rats, laboratory rats and more. The first few give a clear description of how Norway rats do very well in the water. While common house rats were historically found in ships, common rats we're found swimming around in the water underneath wharves and in sewer systems. This differentiated them from the ship rats.

Pet Rats

A fancy rat is a domesticated Norway rat. One of the reasons these rats do so well as pets is that they groom themselves quite a bit. This grooming trait is great in a clean environment but works against these rats when they are exploring an urban landscape. Climbing in dumpsters and sewers all day can coat their fur with harmful organisms. When these are ingested, it can make their droppings a disease threat to humans.  


We left out one name for each of these rats. Norway rats (common rats) are often called brown rats, and roof rats (house rats) are often called black rats. This is because they are predominantly found in these colors. Norway rats can come in other colors, however. They may have some scattered black hairs, they may be a grey color or they may have white fur.  

"Common Rat" Questions

What problems do Norway rats cause?

These rats bring ticks, fleas, and other parasites into your yard and into your home. They spread harmful bacteria, parasitic worms and other organisms. The holes they chew to get into your home can allow other pests to get in. When they roam around inside your home, they can chew on your belongings and leave their waste in many places. Norway rats sometimes chew on wiring and this can cause a house fire. While these rats make great pets, they can be dangerous house guests if they are wild rats.

How big do Norway rats get?

Norway rats are larger than roof rats. They can be as long as 9 inches with an 8-inch tail. A roof rat only gets to be about 5 to 7 inches with a 5- to 8-inch tail.

Do Norway rats live alone?

There can be around five Norway rats living in one burrow. Females will often go off on their own when they are ready to have pups.

How do I get rid of Norway rats?

The best way is to contact Witt Pest Management. Our pest management professionals use field-tested products and strategies to locate and eliminate rodent problems. If you're dealing with any type of rodent in your Pittsburgh home or business, we can help you get control of them. Reach out to us today. 

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