Rats 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:
- They eat food and contaminate it with urine and excrement.
- 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.
- Rats occasionally bite people and may kill small animals.
- They, or the parasites they carry, (such as fleas, mites and worms) spread many diseases.
- 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.
- 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.
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, woodpiles, 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.