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Rodent Control 101: Facts About Mice and Rats


Having a rodent in your home can be stressful and unpleasant. In this section, you’ll learn all of the facts about mice and rats, including: how to identify if you do have an unwanted "guest," the answers to some common rodent myths, and tips on how to rodent-proof your home. When you have a rodent there are some key principles you should remember:

  • Before buying a product, there are some quick and easy steps you can take to help rodent-proof your home.
  • Certain products need to be kept out of reach of children and pets.
  • Some products are only designed for indoor use only and should not be used outdoors.
Know The Signs
Image of rodent droppings types

Mouse Droppings

Usually about 1/8" and black in color.

Norway Rat

Droppings about 3/4" long.

Roof Rat (or Black Rat)

Droppings about 1/2" long.

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Image of rodent footprint types

Tracks can be spotted along areas where rodents travel. Dusting with flour or talc can help spot them. Use a strong flashlight at a low angle to check for tracks and tail drags.

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Image of a rodent gnawing a bag

Evidence of recent gnawing, especially on packaged goods, cardboard boxes and areas around pipes, ducts and vents. Holes can often be found along baseboards and in corner where an existing small hole or crack could be enlarged.

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Dark greasy marks formed by contact with the rat's body. Frequently found along areas where rodents travel.

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 Unusual Pet Activity

Your dog or cat pawing excitedly at a kitchen cabinet, the base of your refrigerator or a wall.

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Do you hear scampering noises in the walls at night? Chewing or gnawing sounds?

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Look for them in the ground, along the outside of buildings.

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Problems Rodents Pose

Rats and mice pose a health risk because they carry and contribute to asthma and allergies and a wide range of diseases.

Asthma and Allergies:

  • A study by The John Hopkins Medical Center shows rodents are a leading cause of asthma in inner city children and have also been shown to aggravate allergy symptoms. -- Journal of Allergy and Clinical Immunology, Dec. 2000.


  • Salmonella, commonly known as “food poisoning,” is caused by ingesting food contaminated with salmonella bacteria often carried by rodent feces.
  • Trichinosis is caused by the infestation of muscle tissue by trichinae, an intestinal parasite spread by rodents.
  • Leptospirosis is infectious bacteria that “drills” itself like a corkscrew into human skin and embeds itself in vital organs, namely kidneys. Humans contract it from walking barefoot on wet, contaminated floors where infected particles float in rodent urine.

Rats and mice are extremely destructive creatues:

  • Eat through cardboard, wood, plaster and even plastic.
  • Gnaw on electrical wiring, which can potentially cause an electrical fire.
  • Contaminate food.
Rodent Myths

MYTH: Rodents can get as big as cats.

FACT: An adult Norway rats don’t typically exceed half a pound with a body about 8 inches long, with a tail nearly as long. That's far smaller than the average cat. The fear many people have of rodents, combined with quick nighttime settings, often results in exaggerated stories.

MYTH: Rodents can live a long time

FACT: Mice in the wild do not normally live much more than a year. In fact, the average mouse lives six to twelve months. Disease, predators, competition and poor weather cut many rodent lives short.

MYTH: Rats and mice don’t have bones, so they can get through tiny holes.

FACT: Rats and mice have internal skeletons like other mammals but they do have very flexible ribs allowing them to squeeze through any gap into which they can fit their head.

MYTH: There is one mouse per person living in a city.

FACT: Next to humans, mice are regarded as the most common mammal in most cities. However, populations rise and fall according to factors like weather, food supplies, shelter and control efforts – not the number of people. There are many mice living in cities, but their distribution is uneven and the absolute numbers are unknown.

MYTH: Only people who live in run-down buildings in poor neighborhoods get rodents.

FACT: Anyone can find themselves with a rat or a mouse problem – even in the most affluent neighborhoods. Rodents seek available food and shelter wherever it can be found – regardless of economics.

MYTH: If you see rats or mice in the daytime, there is a large population around.

FACT: Although primarily nocturnal, rats and mice may move about at any time of the day or night. They are more visible during the daytime because it is easier for people to see them. Sightings usually are not a good indicator of how many rats or mice are living nearby.

MYTH: Cheese is a favorite food of rats and mice and is the best bait for traps.

FACT: Mice and rats don't seek cheese more than other foods. Cheese historically was a common bait because it was readily available and easy to fasten to a trap. Today, depending on the species of rodent present, people commonly use peanut butter, bacon, chocolate or fruit.

MYTH: Rats and mice are not aggressive and will not bite or attack people.

FACT: When cornered, rats can charge or leap at a person, and when handled, wild rats and mice will squeal and bite. Their bite can easily penetrate flesh and cause puncture wounds. Rats also bite sleeping people, especially children, when food odor is present.

MYTH: Rats carried diseases (like the Plague) in the Middle Ages, but today they don't.

FACT: In the U.S. today, the Norway rat has been incriminated in transmitting dozens of different diseases to people, including salmonella, leptospirosis and trichinosis and rat-bite fever.

MYTH: Having cats is good for mouse prevention.

FACT: Not all cats are good “mousers,” and few cats will challenge a rat. Although some cats hunt for mice, many cats tolerate rats or mice, especially when they are well-fed and won't do much for mouse prevention. It could be said that more rats and mice have been fed by cat food than killed by a cat.

Rodent Proofing Tips

Clean Up Common Areas

  • Keep counters, floors, cabinets, and pantries clean and free of crumbs.
  • Clean large household appliances regularly - mice often make those areas their home.
  • Wash all dishes immediately after use for best rat prevention practices.

Eliminate Nesting Areas

  • Keep all storage off the floor at the inside and outside of foundation perimeters.
  • Make sure to clean and organize your garage, attic and basement areas on a regular basis.

Keep Pet Areas Clean

  • Never leave food or water out overnight, even for your pets.
  • Clean up after your pets daily for rat prevention - pet feces are a food source for rats and mice.

Seal Potential Entrances

  • Mice can squeeze through spaces as small as a dime. Seal up potential entrances with sheet metal, steel wool or cement.
  • Check spaces around foundations, pipes, vents and ducts and block them with steel wool or cement. The best mouse and rat prevention is making sure they can't get in.