Pest Droppings Identification: Whose Poop Is This?

Small, dark droppings indoors almost always come from mice, rats or cockroaches; size, shape and where they are tell you which. A mouse dropping is under 1/4 inch, a rat’s is 1/2 inch or more, and cockroach droppings have ridges. The one thing to do: don’t sweep or vacuum them dry, because that puts dust in the air.

This page matches droppings to their likely source, from rodents and roaches to termites and bats, and says how to confirm and clean up. It’s a sorting guide built on CDC, Cornell IPM and UC IPM guidance; a county extension office can confirm a sample.

Whose Droppings Are These? Match Size, Shape and Spot

Main clue	Size and shape	Where you find them	From
Small black pellets, pointed ends	Under 1/4 in, like rice grains	Drawers, cabinets, along walls, behind appliances	House mouse
Large capsule-shaped pellets, blunt ends	About 3/4 in	Along walls, basements, garages	Norway rat
Large pellets, pointed and slightly curved	About 1/2 in	Attics, tops of cabinets, rafters	Roof rat
Pepper-like specks or brown smears	Tiny; smears on surfaces	Cabinet hinges, corners, near sinks	German cockroach
Blunt cylinders with ridges along the sides	About the size of a grain of rice	Basements, drains, laundry rooms	American cockroach
Dark dots that smear like ink	Pinpoint	Mattress seams, bed frames, sheets	Bed bugs
Hard, six-sided pellets in small piles	About 1/32 in, like sand	Windowsills, floors under wood trim or furniture	Drywood termites
Coarse “sawdust” mixed with insect parts	Shavings	Under wood, near damp windows and walls	Carpenter ants
Dark pellets that crumble to powder with shiny bits	About 1/4–1/2 in	Piles below a roost in attics, on walls under gaps	Bats

Scattered small dark mouse droppings along the corner of a cabinet floor

Mouse droppings in a cabinet corner, the way most people first find them. Photo: Matt Frye, New York State IPM Program (CC BY 2.0), via Wikimedia Commons.

Mouse vs. Rat Droppings: Rice Grain or Raisin

Size is the quickest test. Mouse droppings are smaller than a grain of rice; rat droppings are several times bigger. Within rats, Norway rat droppings have blunt ends and roof rat droppings are pointed. Our guide to mouse poop vs. rat poop has photos at scale.

Main clue: smaller than a grain of rice means mice; raisin-size or bigger means rats.

Rodent vs. Cockroach Droppings: Smooth or Ridged

Both can look like small dark specks. Cornell IPM explains the difference: rodent droppings are smooth and often tapered at one end, while cockroach droppings show ridges along their length. Small cockroaches also leave brown smear marks where they rest, which rodents don’t; cockroach poop shows both.

Main clue: smooth and tapered means rodents; ridged along the length, or brown smears, means cockroaches.

Insect “Sawdust” (Frass): Pellets, Shavings or Powder

Frass is the waste and debris wood-boring insects push out. Drywood termites leave tidy piles of hard, six-sided pellets (UC IPM). Carpenter ants push out coarse shavings mixed with dead ant parts. Powderpost beetles leave flour-fine powder below tiny round holes. Subterranean termites don’t leave piles at all; holes in wood helps sort the culprits.

Main clue: six-sided pellets mean drywood termites; shavings with ant parts mean carpenter ants; flour-fine powder means powderpost beetles.

Bat Droppings vs. Mouse Droppings: Crumbly or Hard

Bat droppings collect in piles under where bats roost and crumble into powder with shiny insect fragments when pressed (use a stick, not your fingers). Mouse droppings are hard and stay whole. UC IPM warns never to handle bats or breathe dust from their droppings.

Main clue: droppings that crumble into powder with shiny insect bits mean bats; hard droppings that stay whole mean mice.

How to Confirm Whose Droppings They Are

Measure one next to a grain of rice or a coin.
Look at the ends and sides: tapered and smooth means rodents, ridged means cockroaches.
Note where they are: cabinets and walls, attic rafters, mattress seams or under wood.
Wipe the area clean and check again in a day or two: new droppings mean the pest is still active.

Fresh droppings are dark and slightly shiny or soft; old ones are dull, gray and crumble.

What to Do Next: Clean Wet, Then Treat the Pest

For rodent droppings, the CDC advises airing out the space, wearing gloves, and soaking droppings with disinfectant or a bleach solution before wiping them up; how to clean mouse droppings has the steps. Large amounts of bat or rodent droppings in attics are best left to a professional. Then open the culprit’s page above for how to deal with it.