9 Signs of a Rat or Mouse Infestation in Your Home

Rodent Droppings

Fresh droppings are dark and moist. As rat and mouse droppings age, they dry out become gray, and crumble if touched.

Droppings are most likely found near food packages, in drawers or cupboards, under sinks, in hidden areas, and along walls. 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 whether there is still an active (or new) infestation.

Gnaw Marks

Fresh rodent gnaw marks are light in color and become darker as they age on food packaging or walls. The marks can also indicate whether you have rats or mice. If you had a mouse infestation but you are now seeing larger gnaw marks, you may now have rats.

Odd Pet Behavior

Cats and dogs (or even a pet rat or mouse) often display odd behavior in areas where rodents are present. It 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.

Tracks and Runways

If rodents are active in or around your home, they usually follow distinct runways and tracks leaving smudge marks, footprints, urine stains, or droppings, usually along walls.

Tracks or runways can be detected with a flashlight or blacklight held at an angle toward the suspected area. Not sure? Place a light layer of flour or baby powder on the area. If the rodents are active, you will see their footprints in the powder.

Nests

Rodents use materials such as shredded paper, fabric, or dried plant matter to make their nests. The nest will be in a hidden area but close to sources of food and water. If you see gnawing or droppings, the nest is close and must be removed.

Scratching Noises

If things are going bump in the night, it could be mice or rats. You might hear them scurrying beneath the floors, scampering around the cabinets, or burrowing behind walls and joists. You might even hear muffled squeaking.

Urine Pools

Rats and mice leave urine everywhere. Mice frequently urinate in the same spot around food stuffs creating pillars or small mounds of dirt, grease, and urine. To find the urine pools, use a black or fluorescent light during your inspection.

Ammonia Odor

If an infestation is large, you may detect an ongoing stale ammonia smell indicating an active infestation. The odor is similar to a baby's diaper and differs from the odor of a dead mouse that could be stuck in the wall or hidden area. A dead mouse odor is unforgettably sharp, pungent, and permeates the area.

Allergic Reactions

If someone in your home is experiencing aggravated allergic and asthmatic reactions, it could be due to a rodent infestation. The animals' fur and droppings could be the problem.