Rodent droppings are the most obvious sign of an infestation. Mouse droppings are small, dark, and shaped like grains of rice. Rat droppings are larger, about the size of a raisin. You will typically find them in kitchen cabinets, under sinks, along baseboards, and behind appliances.

What to do: Do not sweep or vacuum droppings dry. Use gloves, dampen with a disinfectant spray first, then wipe and dispose of them in a sealed bag.

Rodents are most active at night. If you hear scratching, scurrying, or squeaking sounds inside your walls, ceiling, or attic after dark, there is a good chance you have mice or rats nesting in those spaces.

In Northern Virginia homes, mice commonly nest in attic insulation and inside wall voids near heat sources. Rats tend to burrow under foundations and in crawl spaces.

Rodents need to constantly gnaw to keep their teeth from overgrowing. Look for chewed corners on food boxes, bags, or cardboard in your pantry. You may also find gnaw marks on wooden furniture, baseboards, door frames, and even plastic pipes under sinks.

Fresh gnaw marks are lighter in color. Older gnaw marks are darker. This can help you tell how recent the activity is.

Mice and rats build nests from shredded paper, fabric, insulation, and other soft materials. Common nesting spots include inside appliance motor housings, behind water heaters, in cluttered storage areas, and inside boxes stored in garages or basements.

If you find a pile of shredded material in a hidden corner, you have likely found an active or recently used nest.

Rats travel the same routes repeatedly, staying close to walls for safety. Their oily fur leaves dark smear marks along baseboards and walls over time. These rub marks are a strong indication of an active rat problem, not just an occasional visitor.

Cats and dogs can detect rodents long before humans notice any visible signs. If your pet is suddenly pawing at walls, staring at appliances, or acting agitated in certain areas of the house, pay attention. They may be alerting you to rodent activity you have not yet discovered.

If you see a mouse or rat during daylight hours, that is a serious warning sign. Rodents are nocturnal and avoid humans when possible. Seeing one during the day usually means the population has grown large enough that competition for food and space is pushing them into the open.

One mouse seen during the day often means dozens are hiding nearby.