Norway Rat

Identifying which rat species you have determines where to set traps and how to approach exclusion. The two most common U.S. rats are Norway rats and roof rats — they rarely overlap in the same building.

Norway rat features: Heavy, stocky body. Blunt muzzle. Ears are small and lay close to the head. Tail is thick and shorter than the body. Found at ground level — burrows, sewers, under concrete slabs.

Droppings: Norway rat droppings are large (3/4 inch), capsule-shaped with blunt ends. Finding large blunt droppings at ground level confirms Norway rats. Smaller droppings with pointed ends = roof rats.

Burrow identification: Active Norway rat burrows have fresh, loose soil outside the entrance, no debris inside, and no cobwebs over the opening. Inactive burrows will have debris, spider webs, and settled soil.

Norway rats are among the most cautious animals in the world when it comes to new objects in their territory. This trait — neophobia — evolved over thousands of years as a survival mechanism in environments where humans tried to poison or trap them.

The consequence: A snap trap placed in an active runway will often sit untouched for a week. The rat detects something new and avoids it. Most DIY rodent control fails because people place traps and check back to find them untouched — concluding traps don't work. The traps are fine — the pre-baiting step was skipped.

Pre-baiting protocol: Place unset traps in active areas for 3–5 consecutive days with attractive bait (bacon, peanut butter, or chocolate). Allow rats to feed freely from the unset traps. Once they are feeding consistently — trigger the trap and set all locations simultaneously on the same night. Catch rates with pre-baiting are typically 3–5× higher than without.

Trapping without exclusion is temporary. Norway rats can squeeze through any gap 1/2 inch or larger. Entry points are typically at ground level: gaps around utility pipes, foundation-sill interface, crawlspace vents, and gaps under exterior doors.

Use Xcluder rodent-proof mesh (stainless steel fill fabric that rats cannot chew through) packed into gaps, followed by Great Stuff PestBlock foam over the top. For larger openings, use 1/4-inch hardware cloth secured with screws.

Also remove attractants: secure all garbage in rat-proof metal cans with lids, eliminate pet food left outdoors overnight, remove fallen fruit, and clear wood piles and debris that provide harborage adjacent to the structure.