Rats and Mice

RatRats and mice can be a problem in urban, suburban and rural areas. They infest old buildings and crowded, unsanitary areas that exist in an urban environment. However, they can also be a problem even where newer homes and sanitary conditions exist. Since these rodents eat practically anything humans eat, they get plenty of food from home gardens, fruit or nut trees and even parts of some ornamental shrubs and flowers. Garbage disposals also attract rats into household and street sewer lines. Rats and mice have long been a problem on farms where food is plentiful and convenient nesting sites are both numerous and hard to eliminate.

There are six major problems caused by rats and mice:

1. They eat food and contaminate it with urine and excrement.
2. They gnaw into materials such as paper, books, wood or upholstery which they use as nest material. They also gnaw plastic, cinder blocks, soft metals such as lead and aluminum, and wiring which may cause a fire hazard.
3. Rats occasionally bite people and may kill small animals.
4. They, or the parasites they carry, (such as fleas, mites and worms) spread many diseases.
5. Rats can damage ornamental plants by burrowing among the roots, or feeding on new growth or twigs. They also eat some garden vegetables, such as corn and squash.
6. Rats and mice are socially unacceptable. These rodents have been a problem for centuries, chiefly because they have an incredible ability to survive and are so difficult to eliminate. In addition, they are extremely compatible with human behavior and needs.

Here are just a few of the abilities that have enabled rats and mice to survive people’s constant attempts to eliminate them:

A female rat can have up to 84 young in her life span, which averages about a year in the wild. They can burrow long distances from nest to food sources, reducing their exposure to predators. The tunnels may extend 4 vertical feet into the earth. They can scale walls and walk across telephone wires with ease. They are excellent swimmers–capable of navigating a half mile through open water. They are amazingly resilient, easily surviving falls up to 50 feet.

Rats – Description:

There are two primary species of rats present in the Pacific Northwest: The Norway rat and the roof rat. The Norway rat is both larger and heavier than the roof rat. It has a wider distribution and is usually more common, although the roof rat may be abundant in some localities, usually near coastal areas. Norway rats build their nests in burrows under buildings, low shrubs or ground cover, wood piles, yard accumulations of junk, and garbage dumps. The roof rat, on the other hand, is a better climber than the Norway rat and is more likely to build its nest in walls, attics, vines or trees.

Norway rat (Rattus norvegicus) – is 13-18 1/2 inches total length, with its tail being shorter than its head and body combined. An adult Norway rat weighs about 3/4 to 1-1/4 pounds. It is mostly brown, with a lighter colored stomach. The tail is semi-naked and darker above than below, giving it a two-toned effect.

Roof rat (Rattus rattus) – is also 13-18 1/2 inches total length, with its tail being longer than its head and body combined. An adult roof rat weighs about 3/4 to 2/3 pound. It is mostly black with some gray below, although there are some variations. The tail is also semi-naked, but of one color.

MouseMice – Description:

We also have two species of mice that cause problems, the House Mouse and the Deer Mouse.

House mouse (Mus musculus) – The house mouse looks somewhat like a young roof rat, but smaller. It is approximately 5-1/2 to 7-1/2 inches total length. Like the roof rat, its tail is as long or longer than the head and body combined. However, mice have proportionately smaller heads and feet than those of a roof rat. The color of the house mouse depends upon its habitat; if it lives indoors it will usually be dark gray with a light gray stomach; outdoors it will usually be a sandy brown color. House mice do not pose as serious a problem to the householder as rats, but they can be quite a nuisance. They also eat and contaminate food with their urine and droppings; may gnaw on wiring creating a fire hazard, and they can transmit some diseases. Spread of diseases by mice, however, is not considered a serious health hazard in our area.

Deer Mouse (Peromyscus maniculatus) – This wide-spread, native rodent is another medium-size mouse, averaging 7 inches total length. The tail is longer than the head and body combined. Upper body is varying shades of brown with white sides and underparts (including chin and throat). Tail is strongly bi-colored. Deer mice have been identified as occasional vectors of Lyme Disease and Hanta Virus and should be controlled around human habitation where these diseases are prevalent. Check the CDC website or your local health department for more information on these diseases.

Rodent Control:

The most important steps in controlling rodents involve sanitation and elimination of their home sites.


1. Store garbage in rodent-proof containers. Make sure your garbage cans have tight fitting lids so dogs or wildlife can’t tip them.
2. Clean up spilled or unused pet food. Store pet food in rodent-proof containers. Failure to do this may lead to serious insect infestations of the feed that rodents often carry into the walls. Also, clean up pet excrement, as rats will eat it if they have to.
3. Do not scatter food for wildlife such as birds or squirrels. Use rodent-proof bird feeders. If rats are a serious problem, eliminate all bird feeders.
4. Compost piles should be properly managed to ensure rapid decomposition of potential rat foods.
5. Clean up fallen fruits or nuts from trees. Prune seed pods from lilac and other shrubs.
6. Store garden/lawn seed, bone meal, etc. in rodent-proof containers.

Eliminate shelters:

1. Employ rodent-proofing features in new buildings.
2. To rodent-proof existing buildings, you should do the following:                                           * repair any cracks or small holes in the foundations
* repair broken windows and doors
* repair broken sewers
* seal any holes, where pipes or wires enter the building, with sheet metal collars or concrete. Repair screens and cover foundation vents with rodent proof screen material.

3. Elevate compost, lumber and wood piles at least 12 inches above ground.
4. Remove unmanaged blackberries or brush near buildings.
5. Prune ornamental shrubs away from the ground and avoid planting ground covers that afford shelter (ivy).

For more information on removing rats, mice or unwanted pests form your home or yard contact Johsnon Pest Control at 865-453-7587.

<< Back To Pest Identification Page

Comments are closed.