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Pest SolutionsPESTS + WEEDSUSING PESTICIDES OR HERBICIDES?
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Rats
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
"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
"Rato (Rattus rattus) - Juvenil" by Cláudio Dias Timm is licensed under CC BY-NC-SA 2.0.
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
"The pear bitten by the rat! 被鼠啃的梨" by Hung Chieh Tsai is licensed under CC BY-NC-SA 2.0.
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's Nest under the Bathtub" by Bart Teeuwisse is licensed under CC BY-NC-SA 2.0.
Rats damage structures and ruin food and belongings. The photo shows a rat nest under a bathtub.
Species: Rat Damage and Entry Point
Liz Kasameyer, Johns Hopkins School of Public Health, Bugwood.org
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
Ed Freytag, City of New Orleans, Bugwood.org
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
David L. Clement, University of Maryland, Bugwood.org
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.
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
High
Salmonellosis transfers via feces. Dried urine and feces particles in the air can trigger asthma.
Property
High
Damage buildings, vehicle, food & belongings
Pets
High
Leptospirosis spreads from rats to pets. Pets can eat poisoned rats and become poisoned themselves.
Annoyance
High
Require control efforts
Environment
High
Invasive animal with no benefit to natural areas
Action Highly Recommended
Take action right away for rats in homes and structures.
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.
Prevent Rats
Weston Miller, Oregon State University
Use Trashcans with Secure Lids
Make sure your trashcan excludes all rodents and clean it from time to time.
Gary Alpert, Harvard University, Bugwood.org
Don’t Leave Trash Exposed
Don’t overfill trash cans and provide a food source for rats.
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.
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.
Weston Miller, Oregon State University
Use Door Sweeps
Install door sweeps that seal the gap between the threshold and the door base.
Gary Alpert, Harvard University, Bugwood.org
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.
Gary Alpert, Harvard University, Bugwood.org
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.
Liz Kasameyer, Johns Hopkins School of Public Health, Bugwood.org
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.
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.
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.
NEED HELP?
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.
Jump to
| Method | Does it work? | Is it safe? | Recommendation |
|---|---|---|---|
A Remove Food Sources & Repair Structures |
Very effective |
Moderate risk |
Recommended |
B Trapping |
Effective |
Moderate risk |
Recommended |
C Toxic Baits (Rodenticides) |
Effective |
High risk |
Use if Necessary |
|
D If Using Rodenticide, Protect Yourself & Minimize Risks
|
A
Remove Food Sources & Repair Structures
Non-Chemical Method
"Neighbourhood Rat" by Tyler Ingram is licensed under CC BY-NC 2.0.
Remove Food Sources & Repair Structures
Recommended
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 | NONE |
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.
"Neighbourhood Rat" by Tyler Ingram is licensed under CC BY-NC 2.0.
Liz Kasameyer, Johns Hopkins School of Public Health, Bugwood.org
B
Trapping
Non-Chemical Method
Weston Miller, Oregon State University
Trapping
Recommended
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? | Effective
|
| 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
|
| Possible risk of exposure or harm from chemicals | NONE |
Set multiple traps and use the prebaiting method described below. Be persistent in your rat-trapping efforts.
Weston Miller, Oregon State University
Weston Miller, Oregon State University
Weston Miller, Oregon State University
"The Rat Trap" by Tony Alter is licensed under CC BY 2.0.
iStock
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.
iStock
C
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? | Effective
|
| 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
|
| Possible risk of exposure or harm from chemicals | El uso de rodenticidas conlleva cierto grado de riesgo. El riesgo más bajo se presenta con el uso de métodos alternativos. You may be exposed to a rodenticide if you:
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.
Liz Kasameyer, Johns Hopkins School of Public Health, Bugwood.org
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
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 for small print.
- 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).
NEED HELP?
The National Pesticide Information Center (NPIC) can answer questions about pest control chemicals.
1-800-858-7378 or npic@ace.orst.edu
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.
HEALTH & SAFETY TIPS
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.
HOW TO CLEAN UP RODENT DAMAGE, FECES & URINE
- 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.
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.
RAT REFERENCES
Rats
University of California IPM
Living with Wildlife: Rats
Washington Department of Fish and Wildlife