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• Norway Rat

Rattus norvegicus

The Norway rat originated in Europe. They are also referred to as brown rat, sewer rat, water rat, pet rat, lab rat and house rat. Historically the Norway rat is most commonly thought of as original carriers of the bubonic plague, which was transmitted via fleas leaving the rodent, and eventually transferring it to humans. Even though the plague has not been found in rats within the United States for many years, rodents in general can carry diseases.

Norway rats are considerably larger than a roof rat. Adults can be up to 16 inches in length from the tip of the nose to the tip of the tail. The tail length is shorter than the body, is scaly in appearance, bi-colored and has almost no hair. The average Norway rat weighs 7-18 ounces. Coloring can range from white to brown, blackish-gray, reddish brown or mottled. The eyes and ears seem smaller in relationship to the size of the head and the nose is somewhat blunt. Females can have 3-6 litters in one year, with 8-9 in a litter. Gestation is approximately 22 days. In the wild, a Norway rat life span is usually no more than a year, but can live much longer in captivity. They are nocturnal, primarily a ground dweller (but is an exceptional climber and occasionally found in attics, on roofs, and other high places) and prefer to live within burrows in the soil. These burrows are often found along railroad embankments, stream or river banks, or near piles of rubbish. Burrows always have at least one entrance hole and at least one emergency exit (or bolt-hole) which is often hidden under grass, debris, etc. Norway rats are very good swimmers and can often live in sewers and underground water systems.

They are opportunistic feeders and will feed on any natural or human foods available. For these omnivores, favorites include meat, fish, cereal and dry pet foods. If any foods are disagreeable to them, they are quick to develop food or bait shyness. With acceptable foods, they tend to eat their fill and return time after time. They will travel 100-150 ft. from the nesting site for food and water, almost always requiring a separate water source aside from that which can be obtained from foods. They have been known to gnaw through plastic or lead pipes to get access to food and water sources.

Like most rodents, Norway rats can be driven inside by lowering temperatures. An opening of 1/2 inch or greater can be a point of access into a structure. Once inside, they tend to nest in basements and the lower areas of the structure within piles of undisturbed debris or merchandise.

Signs of infestation can include: gnaw marks, droppings (adult droppings are about 3/4"), Tracks/footprints, rub marks, and burrows or runways.

Important preventative measures include:

1. Removal of food sources.
2. Removal of debris or anything which could be considered a "harborage site".
3. Securely seal cracks, gaps, and openings around doors, window frames, foundations and siding - keeping in mind that any such areas 1/2" or larger is considered a point of access.

While there are many "self-treat" methods available such as traps and rodent bait or poisons, we strongly recommend no baits or poisons are used unless any interior infestation has been eliminated and access points repaired. Because baits and poisons are very fast acting, rodents may not be able to find an exit point before expiring which can lead to severe odor problems. We recommend these products be used only on the exterior of the home.

If populations remain in excess then a call to Long Pest Control can develop an Integrated Pest Control program to eliminate the sightings and provide control of unwanted rodents year round.