There are dark specks along the mattress seam

Why it will not stop on its own

They shelter within a few feet of where someone sleeps — seams and tags, frame joints, the headboard, a nearby chair, behind a loose skirting board or a picture frame.

They arrive with belongings. Luggage, second-hand furniture, a visitor's bag. Cleaning does not prevent it and does not remove them.

Do not spray them. Repellent products drive bed bugs out of one room into the wall voids, which turns one bedroom into a building problem. In a home that shares walls, that means the neighbours too.

What the visit involves

Confirmation first, because several harmless insects get mistaken for bed bugs and the treatment is too disruptive to run on a guess.

Then a choice of method. Heat treats a whole room in one visit. A chemical programme takes repeat visits, because eggs are not affected by the first application.

Preparation is most of the work and falls on the household — laundry at high heat, bagging what cannot be washed, clearing access to the frame and the perimeter. A treatment run without it usually fails.

What to say when you call

• Where exactly you found the specks
• Whether you have found any insects or shed skins
• Whether anyone is being bitten, and where on the body
• Whether the home shares walls with a neighbour

Common questions

Do I throw the mattress out? Rarely enough by itself. They shelter in the frame and the room, and a new mattress in an untreated room gets colonised.

Do they carry disease? They are not known to transmit disease. The cost is bites, sleep and the treatment.

Could it be something else? Yes, which is why confirmation comes first. Keep anything you find in a sealed bag.