Identify
What do rat droppings look like?
Rat droppings look like dark capsules about 1/2 to 3/4 inch long, much bigger than a grain of rice. Norway rats leave blunt ones in a pile on the basement floor or next to a burrow. Roof rats leave thinner, more pointed ones up on a rafter or the top of a cabinet.
Do not sweep them dry.
Key takeaways
- Capsules about 1/2 to 3/4 inch. Rice-grain pellets in a drawer are mouse, not rat.
- A pile on the floor, in a garage corner, or by a 2 to 3 inch burrow is a Norway rat.
- A pile on a rafter, in attic insulation, or on top of a cabinet is a roof rat.
- A rat squeezes through about 1/2 inch. A mouse uses about 3/8 inch.
- Spray until wet, wait five minutes, then wipe. Do not sweep or vacuum them dry.
Look at where the pile sits before you argue about the ends.
Nebraska puts Norway-rat pellets at about 3/4 inch, with a hole about 1/2 inch and a den opening 2 to 3 inches across, worn smooth. NC State puts a rat at 30 to 50 pellets a day, 1/2 to 3/4 inch long, dark when fresh, paler and crumbly when old. Norway ends stay rounded. Roof-rat ends stay pointier.
A house mouse leaves rice grains along a wall as it walks. Rats use a latrine. You get a pile. Wrong animal: pest droppings guide.
Floor pile or rafter pile
UC IPM keeps Norway rats low: basement, ground floor, burrow along the foundation, trash, woodpile. Roof rats climb. Indoors they use the attic, a false ceiling, a wall void, the top of a cabinet.
| Norway rat | Roof rat | House mouse | |
|---|---|---|---|
| Size | About 3/4 inch | About 1/2 inch | 1/8 to 1/4 inch |
| Ends | Blunt capsule | Spindle, often pointed | Pointed rice grain |
| Pile | Floor, crawlspace, garage, burrow mouth | Rafter, attic insulation, cabinet top | Line along a wall or in a drawer |
| Hole | About 1/2 inch | About 1/2 inch | About 3/8 inch |
A squirrel in an attic can leave blunt pellets in the same size band as a roof rat. Look for nut shells and a chewed roof gap. Pepper specks that smear in a cabinet track are roach droppings.
One pellet will not name the species. Height plus size usually tells you whether to walk the foundation or the soffit.
Put the trap where the pile is
UC IPM: snap traps for Norway rats go on the floor, against the wall, in the dark corner where you found the pile. Traps for roof rats go up: a ledge, a shelf, a beam, a pipe.
Nebraska: a rat fits through about 1/2 inch. Wood and caulk will not stop the chew. Metal or concrete will.
If you see a 2 to 3 inch hole in dirt by the stoop, with the lip worn smooth, that is a Norway den, not a mouse. Follow the runway to food and water. Rats drink. Mice often do not.
CDC: gloves on. Spray until wet. Wait five minutes. Wipe with paper towels. Bag them. Wash your hands after the gloves come off. Do not vacuum or sweep them dry.
Log the room and the height in the sighting log before you wipe, if you can do it without stirring dust.
Pellets back the next night, chew on a pipe or a wire, or a burrow at the foundation: size a rodent job in the estimator and read rodent exclusion cost. Contact for a referral path. Typical US ranges, not a bid.