Record the clue before interpreting it
Photograph straight-on with a ruler. Record diameter, roundness, fresh edges, staining, gnaw marks and height from the floor.
A useful record includes scale, shape, texture, placement and whether the material returns after a clean baseline is established. Avoid changing the scene merely to make identification easier.
What to note
- Exact diameter
- Clean round versus ragged edge
- Fresh dust or pellets below
- Height and nearby route marks
Do not seal an active wildlife opening or cut into a wall with unknown wiring, plumbing or occupants.
Read the full safety guideCommon candidates
These candidates are not ranked until location, scale, pattern, context and timing are added. Open a profile to see confirming and contradicting evidence.
Powderpost beetle
Lyctinae and related groups
Tiny round holes with flour-like powder accumulating below unfinished or stored wood.
Old house borer
Hylotrupes bajulus
Larger oval exit holes, coarse packed frass and feeding sounds in softwood framing.
Drywood termite
Kalotermitidae
Uniform hard pellets in small piles directly below tiny wood openings, often recurring after cleanup.
House mouse
Mus musculus
Small smooth tapered droppings along edges, fine gnawing and shredded nesting material near food routes.
Norway rat
Rattus norvegicus
Large thick droppings, broad gnawing and lower-level routes near foundations, drains or burrows.
Roof rat
Rattus rattus
Slender rat-scale droppings and nighttime movement in attics, rafters or elevated routes.
Big brown bat
Eptesicus fuscus
Crumbly droppings with shiny insect fragments below a high roost or entry, sometimes with fluttering at dusk.
Eastern gray squirrel
Sciurus carolinensis
Daytime bounding and rolling sounds near a larger roof opening, with leaves or bulky nesting material.
Comparisons that resolve common confusion
Side-by-side decision
Mouse vs. cockroach droppings
Size and surface are the fastest split: mouse droppings are distinct rice-like pieces; German-cockroach evidence is usually pepper-like spotting or tiny ridged material.
Open comparison
Side-by-side decision
Mouse vs. rat droppings
Overall length, thickness and associated damage matter more than color. Rat evidence is substantially larger and heavier.
Open comparison
Side-by-side decision
Norway rat vs. roof rat signs
Vertical location is the strongest household clue: Norway rats favor ground and lower levels; roof rats concentrate signs above.
Open comparison
Side-by-side decision
Termite frass vs. carpenter-ant debris
Drywood termite pellets are uniform and hard; carpenter-ant debris is mixed and fibrous, often with insect fragments.
Open comparison
Side-by-side decision
Drywood vs. subterranean termite signs
Drywood termites push pellets from wood; subterranean termites preserve humidity with soil-connected shelter tubes.
Open comparison
Side-by-side decision
Powderpost beetle vs. old house borer
Exit-hole diameter and frass texture are decisive: powderpost signs are tiny and flour-like; old-house-borer signs are larger and coarser.
Open comparison