Droppings, which look like large grains of rice, are often the earliest noticeable sign of a mice or rat problem. Scratching noises coming from the ceiling can indicate black rats while noises from beneath floorboards can indicate brown rats.
You can sprinkle flour or baby powder over a small stretch of floor and check it for tracks the next day. Pick a spot against a wall.
Rats and mice can be highly destructive and will gnaw on plastics, wood and even metal. Holes gnawed in walls or strong odor of urine could be a clue of a problem.
Rats and mice will also go after food and pet supplies. While you wait for your pest control appointment, put dry food in metal or thick plastic containers. Rats can still chew through them, but it can slow the spread of the damage.