Bed bugs do not appear during the day and do not sit in the open, so diagnosis rests on evidence rather than on seeing one. The good news is that the evidence is unmistakable once you know where to look.
Exactly where to look
- Mattress seams and edges: the stitched line around the mattress is always the first place.
- Behind the headboard: particularly a wooden one pushed against the wall.
- Corners of the bed frame and its fixings: narrow, dark gaps.
- Behind the bedside table and the socket nearest the bed.
You are looking for three things: small black specks, as though a pen had been flicked; pale translucent shells, which are skins left behind after moulting; and small blood spots on pale bedding.
Use a torch held low and at an angle rather than the ceiling light. Fine specks disappear under direct overhead light and stand out the moment the light comes from the side. Run the edge of a stiff card along the seam and look at what it brings out, and spread a white sheet on the floor before you lift the mattress so you can see whatever drops. Check the underside as well. Plenty of people inspect only the top face and come away with a false all clear.
What tells you the infestation is old
Early on, the signs stay confined to the mattress, its seams and the frame. Over a few weeks the range widens: black specks at the edge of the rug where it meets the wall, behind a picture hanging near the bed, along the top hem of a curtain, or in the gap between floor and skirting. The further the evidence sits from the bed, the larger the population has grown and the more alternative harbourages it has found.
If the room holds a sofa or an upholstered chair, check their seams the way you would check a mattress seam rather than looking only at the exposed face. Those are the same places washing a sofa or majlis starts from when the aim is cleaning rather than treatment.
By that stage, getting rid of bed bugs means treating the whole room, its furniture and its gaps, not the bed alone. Treat only the mattress and the source is still sitting around it.
Bites alone are not proof
Bed bug bites tend to fall in a line or a tight cluster on skin exposed during sleep, where a mosquito bite is usually single and scattered. But skin reaction varies enormously between people, and one member of a household may show nothing at all. So the decision rests on evidence in the bed, not on skin.
Reaction can also be delayed by several days in some people, which means bites get blamed on the wrong night entirely. That on its own is reason enough not to use skin to work out which room is affected.
How they get in
An infestation says nothing about how clean a home is, and that trips a lot of people up. Bed bugs do not feed on crumbs and have no interest in the kitchen. They arrive as passengers: in a suitcase that sat on a hotel bed, in second-hand furniture, in moving boxes, or through shared gaps and service openings between two flats in the same building.
- Do not put a suitcase on the bed when you get home. Unpack it on a hard floor or in the bathroom.
- Check the seams and drawer corners of any second-hand furniture before it enters a bedroom.
- If a neighbouring flat has been treated, inspect your own room even if you have noticed nothing.
Why treating one room does not end it
Bed bugs travel through gaps between rooms and survive a long time without feeding. Treating a single room pushes them next door and creates the impression the problem is solved, then it returns weeks later. Proper treatment covers connected rooms even where no signs have appeared.
Eggs are also far more resistant than adults, and they are glued inside seams and cracks rather than sitting on open surfaces. That is why the result is judged after the eggs have hatched rather than the day after treatment, and why a follow-up visit is usually what closes the cycle.
What not to do
Throwing out the mattress first is a common and expensive mistake: if the room is not treated, the new mattress is colonised exactly as the first one was. Moving to another bedroom has the same problem, it takes the infestation with you.
- Spraying at random with a shop-bought insecticide: it scatters them into the rooms next door and turns one room's problem into a whole flat's problem.
- Carrying infested furniture out unwrapped: that seeds the corridor and the neighbours.
- Changing the bedding and stopping there: they live in the seam and the crack, not in the cover.
What to do before the inspection
- Strip the bedding into a bag and seal it in the room itself. Do not carry it uncovered through the house.
- Wash it hot if the fabric allows, then tumble dry it. Heat is what finishes the eggs, a cold wash does not.
- Empty the bedside drawers and pull anything sitting flush against the wall away from it, so treatment can reach the gaps.
- Do not spray anything beforehand. An inspection needs evidence that has not been disturbed.
- Do not move a mattress or furniture from the affected room into a clear one.
Everything else about getting a room ready for a crew, from clearing surfaces to naming what stays shut, is gathered in preparing your home before the crew arrives.
After treatment, what is normal
Seeing one or two in the first few days is expected, because the treatment drives them out of hiding. New bites and fresh black specks two or three weeks later are the signal to re-inspect, and that window is when the outcome can genuinely be judged.
A zipped encasement on the mattress earns its place afterwards. It traps anything left inside, and it turns the mattress into a smooth surface where any new evidence shows up at a glance.
Cleaning the mattress itself is separate work with different materials and a different purpose, and it is not a substitute for treatment.
How we do it
We inspect and establish the extent before any treatment, and we will tell you plainly if the case does not warrant it. We explain the safe re-entry period and what needs washing and at what temperature.
Treatment is priced separately from cleaning, because the materials and the rules are different, and it does not normally sit inside a quote for a house clean. What does move that figure is set out in how a cleaning price is worked out.
If you want the detail on method and follow-up, our page on bed bug treatment sets it out in full, or get in touch for an inspection.