Norway Rat

General Description
The Norway rat (also called the brown rat or sewer rat) is a destructive pest found in urban and suburban neighborhoods. These rodents eat and contaminate food, damage buildings and other property by gnawing and burrowing, and can spread diseases that affect people and pets. Norway rats are husky, brownish rodents that weigh about 11 ounces. They are about 13 to 18 inches long including the six to 8 1/2 inch tail. Their fur is coarse and mostly brown, with scattered black on the upper surfaces. The underside is typically grey to yellowish-white. Rats have litters of six to 12 pups, which are born 21 to 23 days after mating. Young rats reach reproductive maturity in about three months. Breeding is most active in spring and fall. The average female has four to six litters per year. Rats can live for up to 18 months, but most die before they are 1 year old.

General Control
Good sanitation will effectively limit the number of rats that can survive in and around a facility. This involves good housekeeping, proper storage and handling of food materials and refuse, and elimination of rodent shelter (harborage). Seal any openings larger than one-fourth of an inch to exclude both rats and mice. Openings where utility conduits enter buildings should be sealed tightly with metal or concrete. Equip floor drains and sewer pipes with tight-fitting grates having openings less than one-fourth of an inch in diameter. Doors, windows and screens should fit tightly. Exclusion, sanitation, trapping and baiting are the most effective control methods. If there is a repeated need for control, it is likely that sanitation and rodent-proofing should be improved.