Our Blog

5 ways to tell the difference between a mouse and a rat infestation in NJ

Tuesday, October 7th, 2014 by Bill Cowley


3 types of mice and norway rat

House mice and Norway rats are both rodents that are very adept at finding shelter in people’s homes. They both are able to squeeze through relatively small holes in a home’s exterior, cause damage to a home and pose health threats to the residents. Mice and rats will commonly infest homes and businesses here in New Jersey. We've seen horse farms in Freehold infested with Norway rats. If you suspect an indoor rodent infestation it’s important to recognize the difference between a house mouse and a Norway rat.

Here are five ways to tell the difference between the two species:

1. Size. The average house mouse ranges in size from two and a half inches to four inches in length. The average Norway rat ranges in size from seven inches to nine and a half inches in length. Although it is easy to distinguish an adult house mouse from an adult Norway rat by their size, there may be confusion if you see an immature Norway rat.

2. Physical Appearance. The house mouse is dusty grey in color with a cream colored belly. They have a long pointed snout, large eyes and small feet. The house mouse’s tail is long, smooth and hairless. The top of a Norway rat’s body is covered with course brown fur that is sometimes scattered with darker, almost black, hairs. Their underside is gray to white in color. The Norway rat has a long, relatively heavy body with a blunt muzzle. The tail of a Norway rat is scaly and semi-naked and is usually shorter than its body whereas the average house mouse’s tail is at least as long as its body if not longer.

3. Destruction Caused by the Rodents. Both house mice and Norway rats are known to gnaw holes in your home. House mice are usually kept from getting into food if the food is stored in glass or metal containers. Norway rats are larger than mice and are stronger. A Norway rat is able to gnaw through many building material, including cinder blocks, aluminum, wood, glass, and even sheet metal.

4. Where they Nest. House mice are very skillful climbers and are able to fit into small spaces. As a result of these abilities, mice can climb through the walls of a home. Walls are used as routes to nests that are found in attics or other quiet places. During the evening hours, especially when it is dark and quiet, you may hear gnawing and scratching coming from inside the walls, or you may hear the sound of running across the ceiling. Although Norway rats can climb they have a tendency to inhabit the lower floors of multi-story buildings. In single- family homes Norway rats are most often found in the basement or in crawl spaces.

5. Reproduction.  An average female Norway rat will be able to wean twenty rats in one year. A female house mouse is likely to have thirty five offspring in that same period of time.

Both Norway rats and house mice can be dangerous to you if they are in your home. They can damage wires that lead to house fires as well as bring diseases into your home that will make you and your family sick. Ridding your house of these pests is both possible and necessary. If you have reason to believe that you have a rodent infestation in your home contact us for a free inspection and quote.