Record the clue before interpreting it
Photograph the object in place with a millimeter scale. Record whether it is attached, ridged, smooth, translucent or open at one end.
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
- Length and width
- Ridges or seams
- Attached versus loose
- Nearby cast skins or adults
Do not crush an unknown case near food or fabric. Bag the item if it can be isolated without spreading material.
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.
German cockroach
Blattella germanica
Pepper-like spotting, small ridged egg cases and nighttime activity clustered near food, water and heat.
American cockroach
Periplaneta americana
Large droppings or dark capsules near drains and humid utility routes, often with a large fast adult sighting.
Oriental cockroach
Blatta orientalis
Shiny dark adults, larger droppings and egg cases concentrated in cool wet lower-level routes.
Bed bug
Cimex lectularius
Ink-like fecal spots, pale cast skins, eggs and flat reddish insects concentrated along bed or furniture seams.
Clothes moth
Tineola bisselliella and Tinea pellionella
Smooth pale larvae, attached silk cases or webbing and clipped natural fibers in dark garment folds.
Indianmeal moth
Plodia interpunctella
Silk-clumped food, webbing in package seams and a two-tone adult moth in kitchens or pantries.
Drain fly
Psychodidae
Fuzzy triangular wings, weak short flight and adults resting near one persistent wet-film source.
Fruit fly
Drosophilidae
Compact tan flies hovering actively around fermenting fruit, beverage residue or recycling.
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
German vs. American cockroach evidence
German cockroaches cluster in warm indoor harborages; American cockroaches are far larger and often travel from humid utility or drain systems.
Open comparison
Side-by-side decision
German vs. Oriental cockroach evidence
Temperature and level separate them: German cockroaches favor warm appliance voids; Oriental cockroaches favor cool damp lower spaces.
Open comparison
Side-by-side decision
American vs. Oriental cockroach evidence
Both favor damp lower spaces; American cockroaches are reddish, larger and warmer-route oriented, while Oriental cockroaches are darker and tolerate cooler wet sites.
Open comparison
Side-by-side decision
Bed bug vs. carpet beetle cast skins
Bed-bug skins preserve a flat insect outline with legs; carpet-beetle skins are hairy and often banded.
Open comparison
Side-by-side decision
Bed bugs vs. fleas
Bed bugs leave seam-centered eggs, skins and spotting; fleas jump and center on animal resting zones with flea dirt.
Open comparison