Does my house have rodents?

Oct 14, 2022, 15:20 PM by Fred Speer

When cooler weather arrives, rodents will seek out shelter for warmth and a new food source. Chances are, they could have their sights set on your home.

How many homes might be at risk for a rodent incursion this fall and winter? More than you think. According to the National Pest Management Association, an estimated 21 million U.S. homes are invaded by rodents.

Clark, your friendly pest, mosquito, termite, and grounds expert, would like to help you focus on the threat posed by rodents, along with how to identify signs of a possible rodent infestation.

The rodent threat

Rodents are a threat to public health, and they also can threaten the structural integrity of your home. Rats and mice spread bacteria and diseases, and they can damage your home by chewing through drywall and gnawing on electrical and computer wiring, which can increase the risk of electrical fires.

Rodents are clever and secretive pests, and they can fit through openings as small as a dime (mice) or quarter (rats) to get inside your home. In addition to being prolific breeders – a female house mouse can give birth to a half dozen babies every three weeks and up to 35 young each year – they are also purveyors of disease and filth.

  • Rats and mice are associated with numerous health risks. In fact, rats and mice are known to spread more than 35 diseases.
  • Rodent droppings can trigger allergies and transmit food-borne illnesses such as Salmonella; one mouse can drop up to 25,000 fecal pellets every year, an estimated 70 times per day.


Signs your home may have rodents

Rodents often leave subtle and not-so-subtle indications that they are present in a home. Here are eight signs that rodents might be closer than you think: 

  1. Droppings: Rodent droppings are a sure sign that rats or mice are present. They will indicate the type of rodent, the size of the infestation, and where they are most active. Mouse droppings are small – less than a quarter inch – and pointed at both ends. Rat droppings are a half inch or larger. New droppings are shiny and puttylike in texture, while old ones are hard and crumbly. Varying sizes of droppings indicate that juveniles and adults are present, and lots of droppings may be an indication of a large infestation.
  2. Urine odors: Rodent urine has a strong musky odor. With large infestations, you can easily smell it.
  3. Gnawed holes: Gnawed mouse holes are small, clear cut, and about the size of a dime. Gnawed rat holes are large, about the size of a quarter, with rough torn edges.
  4. Run and gnaw marks: Oily rub marks are left in places where rodents travel along walls. If rub marks smear, you know they are fresh. Gnaw marks on wood around the house also are a sign. Tooth marks about an eighth inch long are typical of rats, and small scratch marks are a sign of mice.
  5. Rodent pathways: Common rodent pathways generally appear along interior walls, building foundations, ledges, pipes, electrical wires, conduits, tree branches, and fence rails.
  6. Nesting materials: Mice will shred paper, string, and other pliable materials to build their nests indoors. Norway rats nest outdoors in burrows deep in the ground. Roof rats typically nest above ground in attics, trees, or dense vegetation.
  7. Unexplained noises: Rodents are nocturnal. At night they often create scratching sounds as they run inside walls or, in the case of roof rats, in attics and drop ceilings.
  8. Unusual pet behavior: Pets tend to act unusual when they hear or smell rodents in the house. They may appear extremely alert, bark, or begin to paw at spaces beneath refrigerators, stoves, or low-clearance pieces of furniture.

To prevent rodents from gaining access to your residence, it’s important to seal up any holes or openings in the foundation, vents, and utility openings, around doors and windows, or on the roof that may afford them a way inside.

Reducing clutter, making sure that garbage cans are sealed properly, cleaning up food spills, eliminating excess moisture, and storing food in airtight containers are also ways to reduce the threat of rodents this fall and all year long.

Got questions about rodents? Call Clark

Call or text California’s trusted, friendly pest control expert at (800) WE-NEED-YOU (936-3339) or email us at to help protect your home against rodents.

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