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The Norway rat (Rattus norvegicus) is a stocky burrowing rodent, unintentionally introduced into North America by settlers who arrived on ships from Europe. Also called the brown rat, house rat, barn rat, sewer rat, gray rat, or wharf rat, it is a slightly larger animal than the roof rat (Fig. 2). Adult Norway rats weigh an average of 1 pound (454 g). Their fur is coarse and usually brownish or reddish gray above and whitish gray on the belly. Blackish individuals occur in some locations.
Among the diseases rats may transmit to humans or livestock are murine typhus, leptospirosis, trichinosis, salmonellosis (food poisoning), and ratbite fever. Plague is a disease that can be carried by a variety of rodents, but it is more commonly associated with roof rats (Rattus rattus) than with Norway rats.
Frightening: Ultrasonic devices have not been proven to control rats.
Toxicants: Anticoagulant rodenticides (slow-acting chronic-type toxicants): Brodifacoum (Talon®). Bromadiolone (Maki®, Contrac®). Chlorophacinone (RoZol®). Diphacinone (Ramik®, Ditrac®). Pindone (Pival®, Pivalyn®) Warfarin (Final® and others).
Toxicants other than anticoagulants (may be acute or chronic toxicants) Bromethalin (Assault®, Vengeance®). Cholecalciferol (Quintox®). Red Squill. Zinc phosphide (Ridall Zinc®, ZP® rodent bait).
Fumigants: In some situations, outdoor burrow fumigation may be effective. Aluminum phosphide (Phostoxin® and others). Chloropicrin. Gas cartridges. Methyl bromide.
Trapping: Snap traps. Live traps. Glue boards.
Other Methods: Clubbing. Shooting. Dogs and cats are of limited value in some situations.