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. The nose is blunt, the ears are small and close set. The tail is scaly, semi-naked and shorter than the head and body combined. Adult Norway rats weigh an average of about 1 pound. Their fur is coarse and usually is brownish or reddish-gray above, and whitish-gray on the belly. Black coloured Norway rats can occur in some locations. Norway rats can:
- Can pass through any opening larger than ½ inch (1.3 cm).
- Walk along horizontal wires and climb vertical wires.
- Climb the inside of vertical pipes 1 ½-4 inches (3.8-10 cm) in diameter.
- Climb horizontally on any type of pipe or conduit.
- Jump vertically at least 36 inches (0.9 m) above a flat surface.
- Reach about 13 inches (33 cm) above a flat surface.
- Dive and swim underwater for as long as 30 seconds.
- Swim up through the water seal, or trap, of toilets.
- Swim as far as ½ mile (0.8 km) in open water.
- Gnaw and leave marks on almost anything, including wood, chip board, lead pipes, cinder blocks, asbestos, aluminum, sheet metal, glass, and sun-dried adobe.
Signs of Rat Presence:
- Droppings along runways, in feeding areas and near the rats shelter. Fresh droppings are soft.
- Urine along traveled pathways or in feeding areas. Both wet and dry rat urine glows under ultraviolet light.
- Runs or burrows next to walls, along fences, next to buildings or under bushes and debris. Rats memorize these pathways and use the same routes habitually.
- Smudge marks or rub marks on beams, rafters, walls, pipes and other fixtures. These are the result of oil and dirt rubbing off the rats’ fur along frequently traveled routes.
Exclusion is the best control method. All food must be stored in properly sealed jars or tins and kept in containers with tight-fitting lids. Garbage should be prevented from accumulating. Seal all openings to the outside, including wood around doors and windows; repair masonry and seal openings for utility lines, conduits, and drains. Inspect and check outdoor compost areas. Rodent bait, traps, or glue boards are all possible options to control the rat population. The use of labelled rodenticide in exterior bait stations around a property is useful in eliminating an infestation. The use of snap traps with peanut butter bait, chocolate syrup or bacon grease work well. Be sure to pre-bait snap traps.