6 Signs of a Rat or Mice Infestation in Your Home

signs of mice in the home

Illustration: © The Spruce, 2018

If you've had problems with mice or rats in your home, you may have either called in the professionals to eliminate the problem or tried to handle the task on your own. But how do you know for sure the problem has successfully ended? Here are six ways you can tell whether or not your little furry pests are still active in your home.

Determining Rodent Infestation Size

Certain signs can indicate the size of a population. If rodents are seen at night but never during the day, the population has probably not become too large and can be controlled with traps and bait. If you are seeing any rodents during the day, numerous fresh droppings, or new gnaw marks, it is likely that the population has become quite large and may require professional services if you haven't already called in the pest control company the first time you spotted the problem.

Look for these six signs that will help you determine whether you have a current or previous rodent infestation in your home.

  • 01 of 06

    You See Rodent Droppings

    mouse droppings

    The Spruce / Adrienne Legault

    Fresh droppings are dark and moist. As rat and mouse droppings age, they dry out and become old and gray, and easily crumble if moved. Droppings are most likely to be found near food packages, in drawers or cupboards, under sinks, in hidden areas, and along rodent runways. You will find the highest number of droppings where the rodents are nesting or feeding, so inspect the area around the new-found droppings to determine if there is still an active (or new) infestation.

  • 02 of 06

    You See Gnaw Marks

    gnaw marks in drywall

    The Spruce / Adrienne Legault

    In contrast to the droppings, new rodent gnaw marks are lighter in color and become darker as they age. You might see the gnawed holes on food packaging or on the walls. One way to determine age is to compare a gnaw mark you just noticed with those on a similar material that you know to be older. If the newly found marks are lighter in color, it could be an indication of a continuing infestation. The marks can also indicate whether you have rats or mice; larger gnaw marks will have been produced by the larger teeth of rats. If you had a mouse infestation, but you are now seeing larger gnaw marks, you may now have rats.

  • 03 of 06

    There Is a Foul Odor

    cat smelling under stove

    The Spruce / Adrienne Legault

    Cats and dogs (or even a pet rat or mouse) may become active and excited in areas where rodents are present. This is a result of the odor of the rodents' urine and is most likely to occur when rodents have recently entered a structure. If you see your pet pawing at an area in which it had previously had no interest, get a flashlight and examine the area for rats or mice. If an infestation is large, you may also detect an ongoing stale ammonia smell coming from hidden areas, indicating an active infestation. This differs from the odor of a dead mouse that could be stuck in the wall or in a hidden area; That smell is an unforgettable sharp, pungent yet sour odor that permeates the area.

  • 04 of 06

    There Are Tracks and Runways

    sprinkling baby powder to identify rodent pathways

    The Spruce / Adrienne Legault

    If rodents are currently active in or around your home, their runways and tracks are likely to be distinctive, becoming fainter as time passes. Tracks or runways are most easily detected with a flashlight or blacklight held at an angle toward the suspected area. You may see smudge marks, footprints, urine stains, or droppings.

    If you suspect an area is being frequented by rodents, try placing a very thin layer of flour or baby powder there. If rodents are active, you are likely to see their trails in the powder.

    Continue to 5 of 6 below.
  • 05 of 06

    You Find Nests

    rodent nest

    The Spruce / Adrienne Legault

    Rodents will use materials such as shredded paper, fabric, or dried plant matter to make their nests. If these areas are found and have any of the other signs of current presence (fresh droppings, gnawing, odor, or tracks) it is likely that there is still an infestation in your home.

  • 06 of 06

    You Hear Scratching Noises

    mouse scurrying

    The Spruce / Adrienne Legault

    If things are going bump in the night, that could be an indication that mice or rats are still active in your home. You may hear them scurrying along beneath the floors, scampering around the cabinets, or burrowing behind walls and joists. You may even hear muffled squeaking. If you have a cat or other pet, watch to see if they are paying attention to what may be going on behind a wall, then put your ear up to the wall to see if you can hear something which can let you know if there's a problem. Take a pet's interest with a grain of salt; Your pet could have just spotted a spider or a dust bunny!