A confirmed specimen
A captured insect is the strongest starting point. Keep it intact in a sealed clear container or on transparent tape, record where it was found and obtain an expert identification if uncertainty remains.
Faecal spotting
Bed bug faecal marks are dark digested-blood deposits. On absorbent fabric they can soak into the fibres; on a hard surface they may appear as raised dark dots. Random mould, ink and debris can look similar in isolation.
Cast skins and eggs
Nymphs shed pale, hollow skins as they grow. Eggs are very small, off-white and fixed into protected cracks. Either sign is more meaningful beside other evidence in a bed-frame joint or seam.
Bites and blood spots
Bites are non-specific and blood marks on bedding have many possible causes. Treat them as a reason to inspect, not as an identification.
Limits and sources
This page supports triage, not diagnosis. Health wording follows current NHS guidance. Identification logic uses visible anatomy, movement and harbourage evidence; an intact specimen reviewed by a competent expert remains stronger.