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Rat Infestation Warning Signs

Jeannie Knudson
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Rats are one of the hardiest mammals on earth. They are prolific breeders and thrive in a wide range of environments. Unfortunately, when rats make their homes in urban settings, they can cause structural damage to buildings and spread illnesses in people.

Other than actually seeing rats in or around the home, the following warning signs may indicate a rat infestation.


Rats are more active at night, making them easier to hear after dark. When rats are present, you may hear them scratching within the walls or scratching or scurrying around the basement or attic. You also may hear squeaking or chewing noises.


Rat feces are usually the first sign of rat infestation. You may find droppings around baseboards or in dark corners. Additionally, you might find droppings on kitchen counters or in cupboards and drawers, as rats feed and collect food at night. Fresh droppings are black and pellet shaped, while older droppings turn gray and crumbly.


Rats will chew on just about anything. Unfortunately, when they infest a home, they can do costly structural damage. Rats can chew electrical wiring, walls, ceilings, support beams, cupboards or any other hard surface. Not only do they chew to sharpen their teeth, they chew through various substances to get to a food source or to make a shorter route to the source. You may notice a pile of small wood chips where rats chew most often.

Tracks and Markings

You may not notice rat tracks in the house unless it's a dusty location such as a basement or an attic, but if you do notice droppings or signs of gnawing, then sprinkle a little talcum powder or flour over the area and check for tracks after a day or two. If the rats are traveling in and out of a building, they will leave track marks in the soil around the foundation of the building. Additionally, rats tend to stick to a well-traveled path near walls. This practice often leaves dark marks along baseboards or walls where the grease from their fur is repeatedly rubbed off.


Rat urine has a distinct musky scent that is different from domestic pet odors. You’re more likely to smell rat urine and feces in smaller or closed-off areas. Additionally, if nesting in a building, then some rats may have died in a wall, basement, attic or heating duct, or under furniture. A dead rat will smell very badly once decomposition sets in.


Rats nest in dark places where they feel safe. Usual nesting places are in attics, basements, garages or walls. The rats will shred cloth, paper, wood and other materials to build nests. When searching these areas for rat infestation, you may come across a ball of nesting material and food caches. Alternatively, some rats prefer to make burrows along the outside of a building, along the foundation. Burrows are usually found where vegetation is thick or under building materials and wood piles.