Heard it.
Smelled it.
Saw it. Felt it.
Most people don’t arrive knowing the species — they arrive knowing the sign. This pillar maps every common UK pest symptom to a confidence-rated diagnosis, then routes you to identification, treatment and cost.
One sign is noise. Two signs is a pest.
A single fly, a single ant, a single creak in the loft — almost always nothing. The confidence ratings on every symptom page tell you which signs are reliable on their own (rat droppings, wasp nests, bed-bug blood spots) and which only matter when paired (one scratch in the wall plus one set of smear marks = rodent, near-certain).
We group symptoms by the sense that picked them up — hear, smell, see, feel — because that’s how homeowners actually describe them on the phone. Pick the sense, pick the sign, get the species.
Heard it.
Noises in walls, lofts and floorboards — almost always rodents or wildlife.
- HEARD ITDiagnoseDaytime scratching in the loft
Scratching during daylight hours is much more likely to be squirrels than rats.
Identify the pest → - HEARD ITDiagnoseScratching in the loft
Hearing scratching above the bedroom ceiling? Here is what it probably is, how to confirm it, and what to do next.
Identify the pest → - HEARD ITDiagnoseScratching inside the walls
Scratching or scuttling inside walls is almost always rodents. Confirm what you have.
Identify the pest → - HEARD ITDiagnoseScuttling sounds at night
Light scuttling under floors or in cupboards after dark — usually mice.
Identify the pest →
Smelled it.
Musty, ammonia or sweet decay — a hidden colony or a dead specimen.
Saw it.
A live specimen, droppings, smear marks or holes — the most reliable evidence.
- SAW ITDiagnoseChewed wires or cables
Bite marks on cables are a serious rodent indicator and a fire risk. Confirm and treat fast.
Identify the pest → - SAW ITDiagnoseFoxes living under the shed
A fox earth under the shed or decking — humane deterrents and what actually works.
Identify the pest → - SAW ITDiagnoseGreasy smear marks along skirting
Dark greasy marks on skirting boards, walls or pipework where rats run repeatedly.
Identify the pest → - SAW ITDiagnosePigeons roosting on the roof
Pigeons returning to the same spot on your roof or balcony. Proofing options explained.
Identify the pest → - SAW ITDiagnoseSaw a cockroach in the kitchen
A cockroach sighting almost always means more are hidden. Act quickly.
Identify the pest → - SAW ITDiagnoseSilver insects in the bathroom
Fast, silver-grey insects darting across the bathroom floor — silverfish.
Identify the pest → - SAW ITDiagnoseSmall droppings in the kitchen
Small dark droppings near food cupboards or behind appliances. What they mean and what to do.
Identify the pest → - SAW ITDiagnoseSmall holes in jumpers
Holes appearing in wool jumpers or stored clothing — clothes moth damage.
Identify the pest → - SAW ITDiagnoseSudden cluster of flies upstairs
Lots of slow flies appearing in upstairs rooms in autumn — cluster flies.
Identify the pest → - SAW ITDiagnoseTiny round holes in floorboards
Pinhole-sized holes in floorboards or beams indicate woodworm activity.
Identify the pest → - SAW ITDiagnoseTrail of ants in the kitchen
A line of ants leading to a food source. How to identify the species and remove them.
Identify the pest → - SAW ITDiagnoseWasp nest in the eaves
Visible nest under the eaves or in the loft. What to do — and what not to do.
Identify the pest →
Felt it.
Bites, welts, blood spots — biting insects or blood-feeders.
- FELT ITDiagnoseBites around the ankles
Itchy bites in clusters around the ankles or lower legs. Most often fleas.
Identify the pest → - FELT ITDiagnoseBlood spots on the sheets
Tiny rust-coloured spots on bedding are one of the clearest signs of bed bugs.
Identify the pest → - FELT ITDiagnoseTiny bugs on the mattress
Small reddish-brown insects on the mattress seams or behind the headboard. Almost certainly bed bugs.
Identify the pest →
The 1–5 confidence scale.
- 5/5 — Diagnostic. The sign on its own identifies the species (wasp nest, fresh rat droppings, live bed bug).
- 4/5 — Strong. Narrows to one species in >80% of UK cases (smear marks along skirting → rats).
- 3/5 — Likely. Two or three plausible species; pair with a second sign to confirm.
- 2/5 — Suggestive. Worth investigating but easily benign (single fly, one scratch at night).
- 1/5 — Weak. Usually nothing; common in older homes regardless of pest activity.
You have a hunch. Now what?
Confidence 4–5: Skip to the species page, then the cost guide. If it’s rats, bed bugs, wasps or cockroaches, get a quote — DIY almost never wins at this stage.
Confidence 3: Set a 48-hour watch. Add a second piece of evidence (photo droppings, set a sticky trap, listen at the same hour two nights running). If a second sign appears, treat as 4/5.
Confidence 1–2: Do nothing for 7 days. Most weak signs evaporate. If the sign repeats or strengthens, come back and re-diagnose.
Symptom questions, answered.
- What are the first signs of a pest infestation?
- The earliest signals are almost always one of four senses: a fresh sighting (a single mouse, cockroach or wasp), small droppings near food or skirting, night-time noises in walls or lofts, or an unexplained musty smell. One sign on its own is often nothing. Two signs together is a real infestation.
- How do I identify a pest from droppings alone?
- Size and shape narrow it fast: rat droppings are 9–14 mm, dark and tapered; mouse droppings are 3–6 mm and grain-like; cockroach droppings look like ground pepper; bat droppings crumble. Open the matching species page for photo references.
- What does pest scratching in walls sound like?
- Rats scratch heavily at night with thumps and gnawing. Mice scratch lightly and skitter. Squirrels scratch and roll during daylight hours, typically dawn and dusk. Birds in cavities make a softer fluttering. Time of day is the fastest tell.
- Should I worry about a single sighting?
- A single ant, fly or spider is usually nothing. A single mouse, rat, cockroach, bed bug or wasp inside the home is almost never alone — they signal a hidden population. Treat the first sighting of any of those species as a confirmed early-stage infestation.
- Can I identify bites by which pest caused them?
- Bed-bug bites cluster in straight lines on exposed skin, mostly while you sleep. Flea bites cluster around ankles and lower legs. Spider bites are usually single. Mosquito bites are random and itchy raised welts. Use the bites symptom pages for confidence ratings.
- What's the difference between symptoms and signs?
- Symptoms describe what you sense — noise, smell, bites, sightings. Signs are the physical evidence the pest leaves — droppings, smear marks, gnawed cables, shed skins. Both narrow the species, but signs are more reliable for confidence.