Norway Rats

Facts, Identification, & Control

Latin Name

Rattus norvegicus

Appearance

What Do They Look Like?

Norway rat illustration

  • Size: They can reach lengths of 40 cm, and their tails alone can measure 21 cm. They are large rodents that may weigh in excess of 500 grams.
  • Color: Norway rats have fur that is brown or gray in color.
  • Characteristics: These rodents are covered in shaggy fur. Their ears and tails are covered in scales, and their tails are shorter than their head and body.

How Did I Get Norway Rats?

Norway rats will gnaw away parts of the home to enlarge a potential entryway and often burrow their way inside by digging. Older buildings with poor construction and maintenance are at a higher risk for rodent problems.

What Attracts Them?
These rats are accomplished diggers and burrowers, so they are attracted to yards with:

  • Gardens
  • Uncut grass
  • Thick shrubs

Entryways
Norway rats get into homes by entering through gaps and crevices. Rats can fit through holes as small as 1/2 inch. Their most common entryways are:

  • Gaps under doors
  • Holes from utility and plumbing lines
  • Poorly fitting crawlspace doors
  • Poorly maintained wall and foundation vents

How Serious Are Norway Rats?

Disease
Norway rats can be carriers of various diseases that can transfer to humans through rat urine and feces.

Damage
These rodents often severely damage building interiors by:

  • Chewing on wiring or belongings
  • Contaminating food
  • Damaging foundations with their burrows

Signs of Infestation

Some signs of a Norway rat infestation include:

  • Droppings: One of the most well-known signs of a Norway rat infestation are their droppings. These droppings are capsule-shaped and are 18 to 20 cm long. They can be found scattered along frequently traveled rodent pathways.
  • Gnaw Marks: Another sign of these rodents are their gnaw markings on food and objects such as utility lines.
  • Grease Stains: Rub marks or grease stains caused by rats running along an edge also can indicate activity. In general, the darker the stain, the greater the activity.
  • Visual Sightings: Sightings of these pests during the day often indicate large infestations. Outdoor sightings of burrows surrounding the building may be an indication of their nests.

How Do I Get Rid of Norway Rats?

What You Can Do
Read the following tips for keeping Norway rat infestations at bay:

  • Seal Containers: Garbage cans should have a secure lid and be emptied on a regular basis. Food, including bird seed and pet food, should be kept in sealed containers.
  • Block Entryways: Windows and doors should not be left open, particularly overnight when rodents are most active. Any gaps around doors, windows, or chimneys should be closed. Dryer vents should have screen covers, and tree branches touching the home should be trimmed.
  • Reduce Food Sources: Clean up fallen bird seed from the base of bird feeders. Make sure pet food is out of reach from Norway rats. Remove all pet feces in your yard.
  • Reduce Water Sources: Homeowners should fix plumbing leaks, remove outdoor containers retaining water, and ensure spigots and sprinklers are not dripping.

What Orkin Does
Your local Orkin technician is trained to help manage Norway rats and similar pests. Since every building or home is different, your Orkin technician will design a unique program for your situation.

Orkin can provide the right solution to keep Norway rats in their place and out of your home or business


Norway Rat Scurrying

Behavior, Diet, & Habits

Where Do They Live?
Norway rats tend to remain in hiding during the day. They are not usually seen exposed unless driven out of their hiding spaces because of limited space or disturbances.

These pests thrive in a variety of human habitats. While it is believed that they originally lived only within temperate forest regions, they are extremely adaptive and now thrive comfortably in densely populated cities.

These rats live in communities with dominant and subordinate members, though they are not truly social like ants. They make their colony as close to a water source as possible. They typically nest in underground burrows from which they enter buildings in search of food. These rats can be found living in:

  • Attics
  • Basements
  • Crawkspaces
  • Embankments near tree roots
  • Overgrown weedy areas
  • Sewers
  • Soil beneath buildings
  • Woodpiles

Geographical Range
Sometimes called “Norway wood rats” or “Norwegian water rats,” Norway rats are prevalent throughout North America. Arriving on ships from Great Britain circa 1775, these rodents quickly spread throughout the American Midwest. By the 1800s, they were present as far as Ontario, Canada.

What Do They Eat?
Norway rats are omnivorous and feed on a variety of food sources. They are capable of catching small fish and rodents. These pests tend to feed on:

  • Dead animals
  • Fruits
  • Grains
  • Meats
  • Nuts

Reproduction & Lifespan
Norway rats reach sexual maturity in 2 to 5 months and can breed any month of the year. Females can have three to 12 litters per year and litters may number from 4 to 22. Adults generally live up to one year in the wild.

norway rat image

More Information:
Identifying Norway Rats