Identify
Mouse droppings vs rat droppings
Mouse droppings look like dark rice grains, about 1/8 to 1/4 inch long, with pointed ends, usually in a line along a wall or in a drawer. Rat droppings look like dark capsules about 1/2 to 3/4 inch long, usually in a pile on the floor or on a rafter.
Buy a mouse snap for the rice grains. Buy a rat snap for the capsules. A mouse trap will not catch a rat.
Key takeaways
- Rice grain, 1/8 to 1/4 inch, in a line. Mouse-size snap trap. Seal gaps a little bigger than 1/4 inch.
- Capsule, 1/2 to 3/4 inch, in a pile. Rat-size snap trap. Seal about 1/2 inch. Wood and foam will not hold.
- Pellets longer than a rice grain on a rafter are a roof rat, even when the ends look pointed.
- Rice grains in a drawer and capsules in the garage are two jobs. Buy both trap sizes.
- Spray until wet, wait five minutes, then wipe. Do not sweep or vacuum them dry.
UC ANR puts it in one line: you will not catch a rat with a mouse trap, and you will not catch a mouse with a rat trap. Match the trap to the pellet. Pepper specks in a cabinet are a different job: pest droppings guide.
Nebraska puts mouse pellets at 1/8 to 1/4 inch, pointed, about 50 to 75 a day, and they do not collect in piles. A house mouse squeezes through a hole a little bigger than 1/4 inch. Nebraska on rats puts the pellet near 3/4 inch and the hole near 1/2 inch.
Buy the trap that matches the pellet
Mouse-size snaps go on the floor against the wall, in the dark corner of the drawer run. UC IPM keeps them about 10 feet apart. A house mouse rarely travels more than 30 feet from its nest, so a line of rice grains in the kitchen is a kitchen job.
Rat-size snaps go where the pile sits. UC IPM on rats: Norway rats stay low, so the trap sits on the basement or garage floor. Roof rats climb, so the trap sits on a ledge, a shelf, or a beam.
| Mouse | Rat | |
|---|---|---|
| Pellet | Rice grain, 1/8 to 1/4 inch, pointed | Capsule, 1/2 to 3/4 inch |
| Pattern | Line as it walks | Pile, a latrine |
| Trap | Mouse snap, trigger to the wall | Rat snap, floor or rafter |
| Hole | A little over 1/4 inch | About 1/2 inch |
| Seal | Steel wool, 1/4-inch mesh, metal | Metal, concrete, 1/2-inch mesh |
UC IPM: rats chew through plastic, foam, wood, and caulk. Seal openings larger than 1/4 inch anyway. They will gnaw a smaller gap wider.
Pepper specks that smear in a cabinet track are roach droppings. Nut shells in the attic point to a squirrel, not a rat.
Pointed ends on a pellet bigger than rice
Roof-rat pellets can taper. They still run about 1/2 inch, and they sit up: rafter, cabinet top, attic insulation. A house mouse pellet stays in the rice-grain band.
If you are staring at a pellet longer than 1/4 inch, buy the rat trap. The hardware-store mouse trap is built for an animal that weighs about an ounce. A rat steps around it.
Two sizes in one house happens. Rice grains in a pantry drawer and capsules by the water heater are a mouse job and a rat job. Set both trap sizes. Seal to the smaller hole so neither one walks back in.
CDC: gloves on. Spray until wet. Wait five minutes. Wipe with paper towels. Bag them. Wash your hands after the gloves come off.
Log the room, the height, and a coin in the photo in the sighting log before you wipe, if you can do it without stirring dust.
Chew on a pipe or a wire, a burrow at the foundation, or pellets back the next night: size a rodent job in the estimator and read rodent exclusion cost. Contact for a referral path. Typical US ranges, not a bid.