Why Do Bed Bugs Keep Coming Back?

The Pattern That Points At the Building

Three things together, and if all three are true it is worth stopping and changing the approach rather than booking a fourth treatment.

1. Repeated returns after competent work. Not one recurrence, which is common and usually explicable — a repeating cycle
2. A gap of two or three months each time, which is roughly how long it takes a small reintroduction to become noticeable
3. Activity turning up at the perimeter — the shared wall, socket faces on it, the skirting along it — rather than starting at the bed

How They Get Between Flats

• Gaps around pipework and boxed-in service runs, particularly in bathrooms and kitchens backing onto each other
• Cable and conduit routes through party walls
• The void behind a shared partition, in a converted house especially
• Under a poorly sealed flat entrance door into the communal corridor and along it
• Shared laundry, which is faster than any of the above
• Items passed between flats, which is faster still

The structural routes are real and slow — months rather than days. The two at the bottom of that list move a whole flat at a time.

Why Treating One Flat Repeatedly Fails

The sequence is the same every time.

1. Flat A reports it and is treated properly
2. Flat B, which has had it quietly, carries on. Nobody has asked
3. Flat A is repopulated over the following two or three months
4. Flat A is treated again, at Flat A's expense
5. Flat B is still going

That is a scoping failure at building level rather than a treatment failure at flat level, and no amount of work inside one front door resolves it.

What Actually Has To Happen

• An inspection instructed at BUILDING level, not flat level. In practice only a managing agent, freeholder or block manager can arrange that
• The adjoining flats inspected together — above, below and either side, and anything sharing a service run
• Whatever is found treated together rather than in sequence over months
• Communal areas considered, particularly any seating and the laundry
• Proofing of the obvious routes where they are found, which is a building job rather than a pest job

Making the Case

A managing agent asked to inspect a whole block will want more than a suspicion, and a tenant or leaseholder with a record gets much further than one without.

1. Every treatment date, and which rooms were done
2. How long the flat was clear each time
3. Where the new activity appeared each time — the bed, or the shared wall
4. Photographs, dated, in place
5. Anything any neighbour has said, even informally
6. The written recommendation from any inspection, if one said the adjoining flats should be looked at

Six items, sent in writing, is a much harder thing to leave in a queue than a phone call.

Slough: Before Concluding It Is the Building

Rule out the ordinary explanations first, because they are more common than the neighbour one even in a block.

• A room in the flat that was never inspected — including a sofa somebody sleeps on
• Somebody who moved rooms during or after the treatment
• Belongings bagged, stored elsewhere and brought back
• A source outside the property entirely — a workplace, a relative's house, regular travel
• Something second-hand bought since