House Mouse (P. Kelley, Insects Limited)

Mouse droppings (F. Ritchie, NPS)

Rat chewed leather saddle (F. Ritchie NPS)

Mouse damage to candle (T. Parker)

Mouse chewed linden seeds (T. Parker)

Mouse chewed styrofoam (T. Parker)

General Information

Although there are other types of rodents that can wreak havoc on buildings and grounds, mice and rats are the primary rodents that consistently seek harborage inside buildings and storage spaces.

Where can I find general guidance on IPM for rodent control?

What do I need to know to protect my health and safety when handling mouse- or rat-infested materials?



The three most common species of pest rodents are the Norway rat (Rattus norvegicus), the roof rat (Rattus rattus), and the house mouse (Mus musculus), all of which were introduced to North America. There are also native rodent species, though they are less often associated with damage and typically avoid humans. Deer mice and white-footed mice (Peromyscus sp.), as well as meadow mice (Microtus sp.) are exceptions, and may live around or in buildings. Visit the NPS manual on Commensal Rodents for more details.

  • Norway rats are also known as wharf rats, sewer rats, or brown rats. Adults range in size from 12-18 inches (30-46 cm) from nose to tip of tail, and weigh 12-16 ounces (200-500 grams). It has a blunt nose, small hairy ears, and its body is longer than its tail. They are found throughout the United States.
  • Roof rats are also called black rats or ship rats. They are not as stocky as Norway rats, weighing 5-9 ounces (150-250 grams), and measuring 13-18 inches (33-46 cm) from nose to tip of tail. It has a pointed nose, larger hairless ears, and its tail is longer than its body. They are found mostly in coastal areas.
  • House mice weigh from ½ to 1 ounce, and vary in color from light brown to dark gray. They have moderately large ears and nearly hairless tails that are roughly the same length as their body. They are found nearly everywhere that there are humans.
  • Deer mice and white footed mice sometimes become pests when they enter buildings adjacent to woodland or fields. They are similar in size to house mice, with white feet and undersides, and brownish upper surfaces.
  • Meadow mice or voles (Microtus sp.) sometimes become a pest in structures. Unlike house mice, they are less agile, with larger, bulky bodies, shorter tails and small ears and eyes.


Signs of Infestation

How do I know if I have a mouse or rat infestation?

Control and Treatment

How do I pest-proof my facility to prevent a mouse or rat infestation?

Where can I find guidance about rodent exclusion for new construction?

How do I set up a trapping program to monitor for mice and rats?


Food Sources

Mice and rats feed on a wide variety of foods.

  • Norway rats prefer protein-based foods such as meat, fish, insects, pet food, nuts, and grain. They will readily feed on human garbage.
  • Roof rats prefer plant foods such as fruits, nuts, seeds, berries, vegetables, and tree bark. They will occasionally feed on human garbage.
  • Mice feed on cereals, as well as foods high in fat and protein (butter, nuts, meats, etc.), as well as sweets, including chocolate.
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