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Rattus norvegicus and R. rattus
Updated Mar 21, 2023

Make a Positive Identification

Norway rats (Rattus norvegicus) and roof rats (R. rattus) thrive in the Pacific Northwest wherever humans and easy food and shelter are found.

These two non-native rat species have distinct differences as shown in the diagram. The control methods are different for the two species.


Infographic text: Roof rats’ tails are longer than the rest their body. They have a slender body shape. They have big ears and eyes and a pointed snout. Norway rats’ tails are shorter than the rest of their body. They have a sturdy body shape. They have small ears and eyes and a slanted snout.


Species: Norway Rats
Brown and stocky norway rat

"Surmulot" by Gaëtan MINEAU is licensed under CC BY-NC-ND 2.0.

Norway rats are stocky, burrowing rodents. They have blunt snouts. Their tails are shorter than their bodies. Norway rats build burrows near the ground along building foundations and beneath woodpiles and debris piles. Norway rats adapt to crawl spaces. They use sewer/utility passages to move through areas.

Species: Roof Rats
Black and slender roof rat with long tail

Roof rats are slender and agile climbers. They have pointed muzzles. Their tails are longer than their body, as shown in the photo of a juvenile roof rat. Roof rats nest above ground in vegetation or in buildings above ground level.

Species: Signs of Rat Activity
Fruit on counter with rodent gnawing and mess

Norway rats and roof rats are active at night. However, signs of their presence are easy to identify:

  • Rat droppings around pet dishes and pet food storage areas
  • Rat droppings in or around garbage or recycle bins
  • Rat nests in firewood storage, debris piles, storage areas, and garages
  • Feeding damage on fruit from trees and vegetables in the yard
  • Burrows among plants or damaged garden vegetables
  • Debris nests in trees
  • Rats traveling along utility lines or on the tops of fences
  • Smudge marks caused by rats rubbing against floors, beams, rafters, pipes, and walls
  • Large holes and/or burrows beneath a compost pile, garbage can, or other places that offer daytime cover near food
  • Drowned rat in the swimming pool or hot tub
  • Burrows under sheds or dog houses
  • Noises at night coming from the attic, walls, or basement
  • Interest on the part of dogs in holes, small gaps, and climbable structures
Species: Rat Damage
Rat damage in structure

Rats damage structures and ruin food and belongings. The photo shows a rat nest under a bathtub.

Species: Rat Damage and Entry Point
Rat damage and entry point

Liz Kasameyer, Johns Hopkins School of Public Health,

Find rat entry points to buildings. Rats can enlarge small entry holes. Repair the structure and make it rat-proof. Keep rats out with good maintenance practices.

Look-Alikes: Mice & Voles
Species: Mice
House mouse against white background

Ed Freytag, City of New Orleans,

Mice (house mouse) (Mus musculus) are small, non-native rodents found in homes and structures. They cause chewing, feces, and urine damage in buildings. Mice can spread human diseases and trigger asthma.

Take action

Take action right away for mice in structures. Control methods are similar to methods used for rats.

Species: Voles
Vole tunnels in grass

David L. Clement, University of Maryland,

Voles are native species of mice. They live and prosper in grassland and similar settings, such as lawns. The burrowing shown above is a sign of vole activity in a grassy area. They generally don’t damage structures.

Different risks or methods

Mow grassy areas to limit vole habitat.

Voles will gnaw on the bark at the base of trees and shrubs. Protect new plantings of fruit trees and restoration plants with plastic guards to exclude voles.

See Meadow Voles & Pocket Gophers  (OSU Extension Service) for more information.

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Rats Benefits

  • Rats are non-native, invasive rodents in North America.
  • They don’t have any benefits for the environment.

Rats Risks

  • Rats are a health threat to adults, children, and pets.
  • Their gnawing, nest building, and excessive feces and urine cause property damage.
  • Rats chew through insulation on electrical wires.
  • They chew through boxes and plastic bags to get to food and nest areas. Rats ruin stored food and belongings.
  • Rats breed all year. Gestation is about three weeks. Norway rats have 20 or more offspring annually. Roof rats have 20–40 offspring annually. Young rats start breeding when they are 3–4 months old. Rat populations build quickly.
Rats can spread diseases such as murine typhus, leptospirosis, salmonellosis, and rat bite fever. Dried urine and feces particles in the air can trigger asthma.
Risk Card
Does it cause harm?
Adults & Children
Action Highly Recommended

Take Action

Take action right away if you find rat damage in your home or belongings.

Do I need to take action?
Yes, take action right away to control rats. A rat problem will not go away without effort.

What if I do nothing?
Rats reproduce quickly. Rat problems will get worse if you don’t take action.


Consider a licensed pest control company. Learn How to Hire a Pest Control Company.
Your local Extension Specialist in Oregon  and other states  can suggest other methods.

Solutions for Rats

Remove Food Sources and Exclude Rodents

  • Start by removing any food sources like bird seed, pet food, or compost. This sanitation practice must be ongoing.
  • Rodent-proof your home and buildings to exclude them. Fix holes and seal gaps. Use welded wire “hardware cloth” with ¼-inch openings to exclude rats. Use copper or steel wool around pipes and cables.
  • Consider hiring a pest control company or a contractor familiar with rodent-proof construction and exclusion methods. See How to Hire a Pest Control Company for details.

Clean Up Rodent Messes

  • See health and safety tips to minimize risks from cleaning activities.
  • Clean up rodent feces, urine, and damaged items. Use gloves. Spray with a disinfectant before handling rat damage. Wear a dust mask with a HEPA filter. Inhalation of dust from dried urine and feces is where many health problems start.

Control Rodent Populations

  • Get rid of rats using the trapping method described below. Trapping is a good first choice.
  • Carefully consider using toxic bait products (rodenticides). Use a bait station to reduce the risk of poisoning to children, pets, and wildlife by limiting access. Never leave loose bait unattended.

Jump To

Method Does it work? Is it safe? Recommendation
Remove Food Sources & Repair Structures
Very effective
Moderate risk
Moderate risk
Toxic Baits (Rodenticides)
High risk
Use if Necessary
If Using Rodenticide, Protect Yourself & Minimize Risks
Prevent Rats

Remove Food Sources & Repair Structures

Non-Chemical Method

Remove Food Sources & Repair Structures

Before you set traps or use toxic bait, you need to remove food sources and rat-proof your building. Otherwise, rats will return.

Does it work?
Very effective

These steps are required for successful control of rats in home and structures.

How much effort?
High effort

Remove food sources for rodents. Use good carpentry practices and sealing techniques to close off entry points.

What's the risk?
Moderate risk

See health and safety tips to minimize risks from sanitation and rat proofing activities.

Possible risk of exposure or harm from chemicals

Removal of food sources and rodent-proofing your structures are key steps to get rid of rats. After you perform these steps, then use trapping and/or toxic baits to kill an existing population of rodents.

Rat on bird feeder

Remove Food Sources (Sanitation)

  • Removing available food is critical to rat control and must be continuous.
  • Don’t leave pet food, chicken feed, or wild bird seed in a place where rodents can get food.
  • Keep pet food stored in thick plastic or metal bins.
  • Don’t leave food out on kitchen counters.
  • Use rat-proof food compost systems.
  • Clean up fallen fruits and vegetables from orchard and garden areas.
  • Keep garbage in a plastic or metal bin with a tight lid.
Rat entry point through gap under garage door

Liz Kasameyer, Johns Hopkins School of Public Health,

Rodent Proofing and Rodent Exclusion

  • Thin or remove plant growth near buildings that provides hiding cover for rats and their nesting sites.
  • Protect chicken coops with ¼-inch hole aviary wire or hardware wire. Bury the wire below ground. Close any holes larger than a nickel.
  • Repair holes and gaps larger than ¼ inch around doors, windows, crawl space screens, attic vents, and all other building exterior access points.
  • Close gaps around utility service entries such as plumbing pipes by using un-chewable welded wire or steel/copper wool.
  • Securely cover chimneys with a spark arrester.
  • Make sure all exterior doors are tight fitting and weatherproofed at the bottom.


Non-Chemical Method

Weston Miller, Oregon State University


Trapping is an effective way to get rid of rats. It is a good first choice. Follow the directions below for best results.

Does it work?
  • Trapping effectively gets rid of rats when used with preventive measures.
  • You must also remove food sources and exclude rodents from the structure to get rid of them successfully.
How much effort?
High effort

You must set multiple traps and reset them daily until you no longer see fresh signs of rodent activity.

What's the risk?
Moderate risk
  • While setting and cleaning traps, you can be exposed to diseases carried by rodents. See health and safety tips for to reduce risks.
  • Spring-loaded traps can harm children, pets, and wildlife if used improperly. Think carefully about where you place the traps.
Possible risk of exposure or harm from chemicals

Set multiple traps and use the prebaiting method described below. Be persistent in your rat-trapping efforts.

Correctly set rat trap with the bait end against wall

Weston Miller, Oregon State University

Put traps at a right angle to the wall to intercept, rather than block, rodents’ travel.

Paired rat traps at right angles to wall

Weston Miller, Oregon State University

Pairing traps increases your chances of successfully trapping rats. Place traps at a right angle to the wall.

Paired traps with trigger parallel to wall

Weston Miller, Oregon State University

For areas where traps won’t fit at a right angle to the wall, place two traps parallel to the wall with the trigger ends facing outward, along the rat travel route.

Rat trap set inside plastic container to exclude pets & wildlife

"The Rat Trap" by Tony Alter is licensed under CC BY 2.0.

  • Exclude pets and wildlife from rat traps.
  • If you place traps outdoors, keep pets and wildlife from gaining access to the trap.
  • The photo shows a rat trap set up inside a box to exclude pets and wildlife.
Dead rat in trap set on top of fence post and rail


Trapping Instructions for Roof Rats

  • Roof rats are agile climbers, so place traps off the ground in locations where rats are leaving nests to find food.
  • Look for rat activity on ledges, branches, fence tops, and hanging wire.
  • Set triggers at dusk to reduce hazard to non-targets such as birds.
  • Place traps in elevated locations near nests such as attic and garage service platforms and fence tops.

How to Set Rat Traps

  • Trapping is safe and effective in dwellings, garages, sheds, and other structures.
  • Plastic snap traps are easy to set and disinfect.
  • Nuts, peanut butter, cheese, dried fruit, and pet food are good baits for traps.
  • Fasten solid bait securely to the trap trigger with a fine wire.
  • Set traps so the trigger will spring easily.
  • Place traps where rats travel so they will pass directly over the trigger of the trap. Look for rat droppings and gnaw damage and install traps there.
  • Place traps along walls, behind boxes, and under equipment and furniture.
  • A dozen or more traps in an infested home is appropriate. Place rat traps roughly 10-20 feet apart.
  • Check the trap every 24 hours.
  • Remove and dispose of killed rats and reset the traps. Wear disposable gloves or rubber gloves that can be disinfected.

PrebaIting Method

  • Rats are cautious of new things in their environment.
  • Prebait the traps.
  • Bait and place traps without setting them to snap. Bait will often be taken in a single night.
  • If bait is taken from all traps, add more traps. Consider doubling the number of baited traps.
  • Plan on several nights of baiting unset traps.
  • Then bait and set all traps.
  • Continue baiting, cleaning, and setting traps until the population of rats is gone.
  • The process described above helps rats learn to ignore the traps. It makes your trapping more effective once you set the triggers.

Other Trap Options Have Disadvantages

Battery Traps

Battery-operated electrocution traps have been shown to provide good control of rats. They are considerably more expensive than snap traps.

Live Traps

  • Live catch traps are boxes that have an entrance but no exit, and do not injure rats. However, trapped rats may be noisy as they try to escape. When you use these traps, rats have to be removed and humanely euthanized with a strong blow to the head. Drowning is considered inhumane. Releasing live rats caught in the traps won’t solve your rat problem.
  • Glue boards are pieces of flat cardboard with a thick layer of glue on one side, similar to fly paper. Rats don’t die quickly and struggle to get free. If you find a live rat in a glue board, it must be immediately and humanely euthanized with a strong blow to the head.
A live mouse trapped in a glue trap


Glue boards don’t kill rodents right away. If you find a live rodent in a trap, you must humanely euthanize it.


Toxic Baits (Rodenticides)

Chemical Method: Use with caution

Weston Miller, Oregon State University

Toxic Baits (Rodenticides)

Use if Necessary
  • Rodenticides effectively control rat populations when used according to label directions.
  • Use rodent bait stations to minimize access to the toxic bait by humans, pets, and wildlife. The white box on the example rodenticide label highlights “Child & Dog Resistant.”
Does it work?
  • Toxic baits are effective when used with preventive measures.
  • You must also remove food sources and exclude rodents from the structure to get rid of them successfully.
How much effort?
Moderate effort

Many rodenticide product labels recommend maintaining fresh bait in bait stations until there are no longer signs of new rodent activity.

What's the risk?
High risk
  • Using toxic baits comes with real risks. ALWAYS read the entire label front to back. Review instructions even for brands you know.
  • Rats poisoned by toxic bait can die inside walls and crawl spaces. Decomposing rat bodies smell bad and create a human health hazard.
  • Rodenticides are toxic to children, pets, and wildlife.
  • If used according to the instructions, bait stations are “Child & Dog Resistant” as stated in the white box on the example product label above.
Possible risk of exposure or harm from chemicals
Using rodenticides includes some amount of risk. The lowest risk comes with using alternative methods.

You may be exposed to a rodenticide if you:

  • Get it on your skin
  • Breathe it in
  • Eat or smoke afterward without washing hands
  • Bring it inside on your shoes or clothes

Follow directions closely to reduce risk.

It is critically important that you follow rodenticide product directions to place bait stations properly and legally inside buildings or near the building perimeter.

Open rodenticide bait station

Liz Kasameyer, Johns Hopkins School of Public Health,

  • If you choose to use rodenticide products, make sure to use bait stations to exclude children, pets, and wildlife from the toxic bait.
  • Never leave unsecured bait unattended.

Rodenticide Active Ingredients

Warfarin, chlorophacinone, diphacinone, and cholecalciferol are common active ingredients in rodenticide products for use in homes and structures.

Tips for Using Rodenticides

  • Place bait in tamper-proof bait stations that limit access to the toxic bait.
  • Poisoned rodents sometimes die in hard-to-reach places, decay in place, and then smell bad and create a new health hazard.
  • Collect and dispose of any dead rodents. See health & safety tips.
  • Bait products take several days to kill rodents.
  • Ensure the stations are continuously supplied with bait. Replace moldy or damaged bait.

Bait Placement for Norway Rats

Place bait stations against walls in travel routes near burrows and nest sites.

Bait Placement for Roof Rats

Secure bait stations in elevated locations near nests. Example locations include attic and garage service platforms and fence tops where they travel.

Remove Food Sources and Repair Structures BEFORE Using Toxic Baits

  • If you don’t remove food sources and secure your buildings, toxic baits won’t get rid of rats.
  • You’ll have to keep using poison bait repeatedly.
  • If you can’t block access or remove rodent-nesting areas, ongoing baiting is allowed.
Products with active ingredients brodifacoum, bromadiolone, difenacoum, difethialone, zinc phosphide, and strychnine aren’t generally permitted in residential (home and structures) applications. These rodenticides are labeled for use in industrial and agricultural settings. They require a pesticide applicator’s license.

If Using Rodenticide, Protect Yourself & Minimize Risks

Chemical Method: Use with Caution
Dog and cat in house

chendongshan, iStock

Rodenticides are extremely toxic to humans, pets, and wildlife. Baits are made to attract animals with tasty smells and flavors. Pets and wildlife can be poisoned if they eat rodents that consume rodenticides.


Why Is It Important to Read Rodenticide Labels?

  • They have detailed information on how to use the product correctly and legally.
  • They contain information about specific rodent species, their habits, and control methods.
  • They provide information on potential hazards of the product, and instructions you should follow for poisonings and spills.

The Label is the Law

ALWAYS read the label before using rodenticide products. The label is a legal document that provides information on how to safely use the rodenticide. This helps avoid harm to human health and the environment. Using a rondenticide in off-label ways is illegal. It can result in legal enforcement actions.

READ THE LABEL & Follow Instructions
It has instructions to protect you and the environment.

  • Labels are different for every product and they often change over time.
  • Use a magnifying glass.
  • Pay attention to CAUTION, WARNING, and DANGER statements.
  • Pay attention to the PRECAUTIONARY STATEMENTS.
  • The law states you must read and follow rodenticide instructions.

Protect Children, Pets, Domestic Animals & Wildlife
Children, pets, and wildlife are at risk if they touch or consume poison toxic bait for rodents.

  • Keep rodenticides out of reach from children and pets at all times.
  • Dogs, cats, and wildlife are also attracted to and harmed by rodenticides.
  • Use bait stations to protect children, pets, and wildlife.
  • Rodenticides may be gathered by mice or rats and cached for later use. The cache location may not be safe for pets or children.
  • Dogs, cats, and wildlife can be poisoned if they feed upon rats that have eaten rodenticide.

Protect Yourself
Eye, skin & lung irritants

  • Wear gloves and safety glasses when handling rodenticides.
  • Avoid contact with eyes, skin, or clothing.

Storage & Disposal

  • Store out of the reach of children and pets.
  • Follow the label instructions for disposal of rodenticide products.

Call  1-800-CLEANUP (1-800-253-2687) to find out where to dispose of pesticides.

For the Portland metro region in Oregon, contact Metro’s Recycling Information. Call  503-234-3000, email   or visit Metro’s website  

More about:

About Using Pesticides on School Grounds in Oregon

If using pesticides on school grounds, there are special rules in Oregon. See School Integrated Pest Management  (Oregon Department of Agriculture).


The National Pesticide Information Center (NPIC)  can answer questions about pest control chemicals.
 1-800-858-7378 or  

Consider using a licensed pest or weed control company. Learn How to Hire a Pest Control Company.

Your local Extension Specialist in Oregon  and other states  can suggest other methods.


Prevent Rats

Trash, yard debris, and recycling bins with sturdy lids

Weston Miller, Oregon State University

Use Trashcans with Secure Lids

Make sure your trashcan excludes all rodents and clean it from time to time.

Open trash can with food and debris

Gary Alpert, Harvard University,

Don’t Leave Trash Exposed

Don’t overfill trash cans and provide a food source for rats.

Rigid plastic container for pet food

Weston Miller, Oregon State University

Store Pet Food and Bird Seed in Robust Containers

Exclude rats from bird seed and pet food by using containers made of thick plastic or metal and a secure lid.

Food scraps

Weston Miller, Oregon State University

Don’t Attract Rats with Food Scraps in Your Compost
  • If you compost food scraps at home, use a rat-proof composting system.
  • If your compost area is not rat-proof, avoid including meat, milk, and bread products that won’t break down quickly. Keep mixing and maintaining the pile so heat stays high and breaks materials down fast.
Door sweep and threshold

Weston Miller, Oregon State University

Use Door Sweeps

Install door sweeps that seal the gap between the threshold and the door base.

Hole in foundation showing rodent entry point

Gary Alpert, Harvard University,

Seal Gaps in Construction
  • Fill entry points as small as a dime with sealant and/or steel or copper wool.
  • Larger holes similar to the hole in the building foundation shown in the photo need to be filled with concrete.
Pipe through floor with gap allowing rodent access

Gary Alpert, Harvard University,

Use Good Carpentry Practices
  • Seal around water, gas, water service pipes, and conduit installed in walls and floors. The space between the pipes allows access for rats.
  • Use good carpentry practices and sealing techniques to close off entry points.
Dryer vent with proper screen to prevent rat entry

Liz Kasameyer, Johns Hopkins School of Public Health,

Seal Exterior Vents
  • Maintain and repair all building ventilation screens, louvers in attic spaces, and furnace closet doors and vents.
  • Any gaps around the screen frames and louvers require sealing.
Shelving pulled back to expose wall with exposed studs for rat monitoring

Weston Miller, Oregon State University

Declutter and Check for Signs of Rats
  • Declutter storage spaces to eliminate places rats can hide. Pull boxes and items away from walls and shelves as shown in the photo.
  • Monitor for rat activity. Clean the area as needed.


Use disposable or rubber gloves to clean up dead rodents and their feces, urine, and nests.

Wear a dust mask with a HEPA filter when cleaning an area that has excessive rodent droppings and damage.

Don’t use a broom or vacuum. These actions may cause the viruses and bacteria living on the rodent droppings to become airborne. Inhaling those could make you sick.


  • Wet the stained or damaged area with a disinfectant. Disinfectants such as 10 percent bleach/water solution will kill disease-causing bacteria and viruses.
  • Apply a disinfectant and wait ten minutes. Use a moist cloth or paper towel. Wipe up the droppings and mouse damage.
  • Put all the waste, including your disposable gloves in a trash bag. Dispose of it right away.
  • If you use a washable cloth and reusable gloves, clean those items in soapy water and disinfectant.
Gloved hand cleaning rodent damage

Content provided by editor Weston Miller and writer J. Jeremiah Mann. Vertebrate information edited by Dana Sanchez. Pesticide safety information edited by Kaci Buhl.

 Peer reviewed by OSU Department of Horticulture.

Photo of Weston Miller

Weston Miller

Project Founder and Content Writer

Weston Miller served as Community and Urban Horticulture faculty for Oregon State University Extension Service for Clackamas, Multnomah, and Washington Counties. Weston is an author for content for this website. He developed funding partnerships with Portland area agencies to initiate and build out the Solve Pest Problems website focused on this goals:

J. Jeremiah Mann

J. Jeremiah Mann

J. Jeremiah Mann completed a Physical Science undergraduate degree at Humboldt State University, and M.S, Ph.D focusing on plant science topics at UC Davis. He went on to work for the Natural Resources Conservation Service and in a leadership position serving a private agricultural technology company. He currently lives in Sacramento California where he consults on pest and property management topics.

Photo of Dana Sanchez

Dana Sanchez

Dr. Dana Sanchez, Extension Wildlife Specialist, addresses wildlife-related questions on Ask Extension and produces Extension publications, webinars, and presentations to groups such as Master Gardeners. She also conducts research on native mammal species of the West in collaboration with her graduate students and undergraduate research interns.

Photo of Kaci Buhl

Kaci Buhl

At the state level, I lead the Pesticide Safety Education Program (PSEP). The program hosts live recertification events around the state, serving over 1,000 licensed pesticide applicators each year. We also produce web-based training modules and license-preparation study manuals. Special training for unlicensed pesticide applicators is also available through a grant from the USDA Specialty Crop Block Grant Program. The PSEP at OSU works closely with the Oregon Department of Agriculture's Pesticides Division.