These rodents have heads and feet that are much smaller than rats, and they are often gray in color. House mice are also nocturnal, and while they eat very little, they leave around 50 droppings on your property every day. They tend to live out of sight in warm areas such as clothing or insulation materials. They are adept at spreading disease, particularly salmonella, which is why touching their feces can be dangerous, especially for small children.