Why Do Bed Bug Infestations Come Back?

Start By Writing the History Down

Almost nobody has this, and without it the conversation is guesswork on both sides.

1. Date of each treatment, and exactly which rooms were treated each time
2. Which rooms were inspected but not treated — this is usually the answer
3. How long the property was clear after each
4. Where the new activity appeared each time: the bed, the perimeter, a different room
5. The size of the insects each time: nymphs or adults
6. Anything that changed in between — travel, visitors, furniture, somebody moving rooms

The Audit: Six Questions

1. Was every bed in the property inspected, or only the ones with bites?

By a distance the commonest answer. Beds nobody sleeps in produce no bites, so nobody asks for them to be looked at — and an unused bed does not clear itself.

2. Was anything treated in sequence rather than together?

Two rooms treated three months apart give an untreated population somewhere to sit while the first is done, and somewhere to return from afterwards. It is a scoping failure that looks exactly like a treatment failure.

3. Has anybody been sleeping anywhere other than their own bed?

During or after any of the treatments. A sofa, a spare room, a child's floor. Ask everyone, without blame — it is rarely volunteered.

4. Did anything come back into the room afterwards?

Bagged clothing that was stored elsewhere, furniture that was moved out and returned, a mattress topper that went in a loft. Anything that left an infested room and came back untreated.

5. Is it a flat, an HMO or a shared house?

Then the unit is the building rather than the property, and no amount of work inside one front door resolves it. This needs a building-level inspection, which usually only a managing agent can arrange.

6. Is there a source outside the property?

The one nobody wants to consider. A workplace, a vehicle, a relative's house where somebody stays regularly, ongoing travel, anything second-hand bought since. A source that is still active delivers indefinitely, and it is the version that repeats until it is found.

What To Change Before Booking Again

• Widen the inspection to every bed and every seat in nightly use, whatever the previous scope was
• Insist on together rather than in sequence if more than one room is involved
• Ask for the finding in writing, room by room, including what was checked and left
• Ask whether a follow-up forms part of the work this time
• Deal with the source if the audit points at one. A treatment does not address it
• Clear the evidence field afterwards so the next few weeks are readable

Thatcham: What Not To Do

1. Do not book the same scope a third time and hope
2. Do not start again with shop-bought products — it widens the spread and destroys the evidence
3. Do not throw out furniture in frustration. It is rarely the answer and it is never the whole of it
4. Do not move out of the room. It gives a surviving population a new destination
5. Do not stop keeping the record. This is exactly when it becomes valuable