While there are a wide variety of species of mice, their overall appearance is very similar. Most mice range from 5-10 inches in length. Their ears are much larger than rats, particularly in comparison to their small frames. A few common mice are house mice, field mice, deer mice, and wood mice. Most mice find their way indoors through minor cracks, open doors, windows, wall cavities, etc. While the presence of mice may not strike as much fear in humans as rats do, they still present a large threat to the home or business owner.