Norway Rat


Actual Size: 16” long including the tail

Characteristics: Robust bodies. Typically grayish-brown can be reddish-brown to blackish.

Habitat: Dug 6.5 feet long burrows along property lines and gardens. Will nest in basements and crawl spaces of homes.


  • Also known as the “brown rat” or “sewer rat”.
  • Tails are hairy and shorter than their head and body combined.
  • Prefer to live in underground burrows, basements, and tunnels.

Norway Rats in Iowa

Norway rats are one of the more dangerous pest problems for homeowners. These rats are stocky, heavy-bodied, and are larger and more aggressive than their cousin the roof rat or black rat. Found throughout the United States, Norway rats are commensal rodents, living near and dependent on the human habitat for survival. Norway rats will eat almost anything but prefer cereal grains, meats, fish, nuts, and some fruits. Like most rodents, Norway rats are most active an hour after sunset and just before dawn. The gnawing activity of Norway rats can cause considerable damage to homes, gardens, and structures. Norway rats are carriers of serious diseases, which is why their infestations can be so dangerous.

Norway Rat Habitat

Norway rats like to burrow underground when they nest. They will either build their burrows or re-use burrows leftover from past pests. The burrows they construct can be 2 to 3 inches in diameter and up to 6.5 feet in length. Burrows are constructed outdoors beside foundations and gardens. Norway rats are nocturnal and will enter homes at night in search of food, returning back to their burrow.  If nests are found inside homes, they are typically in basements and crawl spaces. If a population is large, Norway rats will nest in the upper areas of a home or structure.

Norway Rat Behaviors, Threats, or Dangers

Norway rats are some of the most dangerous rodents. They can damage foundations, slabs, garden crops, and plants as they burrow and gnaw to find food and shelter. Inside homes, Norway rats may cause extensive damage when nesting in walls and attics. Accounts of rodents starting fires through the gnawing of electrical wires have been widely reported. Chewed, exposed wires inside walls can spark, causing interior walls to catch fire. When foraging for food, these rats consume and contaminate food meant for humans, pets, and livestock. Some of the diseases that can be spread by Norway rats include Salmonella, leptospirosis, and rat-bite fever. If you are dealing with Norway rats on your property, it’s time to contact your local rodent exterminators.