Mice build their nests out of fibrous, fluffy material, such as shredded paper, dry grass, twigs, fabric and furniture stuffing. Look for nests in sheltered areas of your home such as inside cabinets, under or in dressers, in boxes, behind and in large appliances, inside furniture, inside double walls, and in the space between floors and ceilings for nests.
Nibbling and Gnawing
Tooth marks on chair legs and other low-lying surfaces may indicate an infestation. Mice keep their constantly growing teeth short by gnawing on everything from wood and paper to cloth and plastic. Also, look for food packages that appear to be nibbled, and "feeding stations" where you'll see food remnants, pieces of plastic and other packaging material, and cockroach carcasses.
See or Smell a Mouse
Mice are usually active at night, but occasionally you'll see one out and about during the day. However, you're more likely to smell their musky odor first.
The most common sign of a mouse infestation is droppings, or feces, in your cabinets, pantry or other protected places where mice can find food and shelter. Mice feces are black, ¼ inch long and granular in shapes. They carry salmonellosis, the bacterium that causes food poisoning; and hantavirus, which is usually deadly if contracted by humans.
What to Do
If you see signs of mice in your house, certain measures can prevent and control the infestation. Keep your house clean and free of food crumbs and places where mice can seek shelter. Mouse-proof your house by sealing any openings where a mouse can gain entrance to your home. Set out traps and poison baits in areas where pets and children can't access them. If all else fails, hire a professional exterminator.