Norway Rat

Rattus norvegicus

Norway rat

Norway rat (National Park Service, Wikimedia Commons)

norway rat

Norway rat (Tomas Cekanavicius, Wikimedia Commons)

Norway rat

Norway rat (David Shankbone, Wikimedia Commons)


  • average length is 16 inches
  • gray to reddish brown; typically grayish brown

Nesting Habits

  • nest in burrows in the ground
  • like low-growing vegetation, rock piles, etc.
  • very common under concrete slabs


  • highly varied: any food product, trash, carrion, etc.


  • can transmit disease; human health concern
  • ruin stored food products
  • nuisance in and around buildings

IPM Recommendations

  • Install tight-fitting door sweeps.
  • Seal exterior cracks, crevices and areas around pipes and electrical that enter buildings through walls.
  • Reduce clutter indoors and outdoors.
  • Remove weeds and low-growing ornamentals/covers.
  • Move dumpsters at least 50 feet from buildings.
  • Keep all exterior doors closed.
  • Store food in pest-proof containers.
  • Use snap-traps placed with triggers toward the baseboards, especially in dark corners and behind objects, in drop ceilings, and areas with droppings, etc.
  • Use multiple baits: peanut butter, meat, candy, etc.
  • When trapping, put traps out with bait, but do not set the triggers. Desensitize the rats for a week before setting the triggers.
  • Train kitchen and custodial staff to clean thoroughly.

Additional Resources:

IPM for Rats and Mice: Integrated Pest Management in Sensitive Environments (University of Nebraska-Lincoln Extension)