Shop-bought bed bug sprays can kill individual bed bugs on contact, but they very rarely clear an infestation. Most retail sprays do not affect bed bug eggs, do not reach the cracks and crevices where bed bugs hide, and are increasingly ineffective against the resistant bed bug populations now common across London and Essex. In many cases, spraying makes the problem harder to treat by scattering bed bugs into new hiding places. This article explains what sprays can and cannot do, and what professional treatment involves.
The short answer
A can of bed bug spray from a supermarket or DIY shop is a contact killer. If the spray lands directly on a bed bug, it will usually kill it. The problem is that the bed bugs you can see are a small fraction of the infestation. The rest are hidden in bed frames, mattress seams, skirting boards, behind headboards and inside furniture joints, along with their eggs. A spray that only kills what it touches cannot reach them, so the infestation continues.
Bed bugs are resistant to the insecticides sold to the public
This is the single most important reason retail sprays fail, and it is rarely mentioned on the packaging.
Almost every bed bug spray sold in supermarkets, hardware shops and online marketplaces is based on pyrethroid insecticides such as permethrin, deltamethrin or cypermethrin. Bed bugs have been exposed to this chemical group, and to the chemically related DDT before it, since the 1950s. Populations that survived passed on the traits that allowed them to do so, and those traits are now common in the bed bugs found in UK homes.
Resistance works in several ways at once:
- Nerve target changes. Mutations in the sodium channels of the nervous system, known as kdr and super-kdr, reduce the effect of the insecticide at the point where it is supposed to act.
- A tougher outer shell. Resistant bed bugs have a thicker cuticle, which slows how much insecticide reaches the nervous system in the first place.
- Faster breakdown. Raised levels of detoxifying enzymes allow resistant bed bugs to break the insecticide down before it takes effect.
The practical consequence is that a spray which kills a susceptible bed bug in a laboratory may leave a resistant one alive in a bedroom in Romford or Ilford. A sublethal dose also does more than simply fail. It irritates. Bed bugs that survive contact move away from the treated surface and settle somewhere new, which is why spraying so often coincides with an infestation appearing to spread rather than shrink.
Professional treatment addresses this by using products with different modes of action to pyrethroids, none of which are available to buy without professional registration and training. That difference in chemistry, rather than simply strength, is what separates a technician’s treatment from a can bought off a shelf.
Why sprays fail against a real infestation
Resistance, covered above, is only part of the problem. Even against a fully susceptible population, a retail spray faces three further obstacles.
Eggs survive. Bed bug eggs are protected by a coating that most consumer sprays cannot penetrate. Even if a spray kills every adult it touches, the eggs hatch within one to two weeks and the infestation returns.
Bed bugs hide where sprays cannot reach. Bed bugs spend most of their time in harbourages: tight cracks, seams, screw holes and gaps in furniture. A surface spray applied around a bed does not reach them.
Spraying scatters the infestation. Many consumer products have a repellent effect. Rather than killing hidden bed bugs, they push them deeper into walls and furniture, into adjacent rooms, and in flats and converted houses, sometimes into neighbouring properties. This is common in the older converted terraces and purpose-built blocks found across Romford, Ilford and Barking, where bed bugs can move between flats along pipework and cavities. A scattered infestation takes longer to treat than one that has been left undisturbed.
Do sprays have any legitimate use?
In a very limited way. A contact spray can kill a bed bug you have found and can be a short-term measure while professional treatment is arranged. What it cannot do is act as a control strategy. Bugwise regularly treats properties where residents have spent weeks and a considerable amount of money on sprays, powders and foggers, and the infestation has grown throughout.
Foggers and bombs deserve a specific mention: they are one of the worst options for bed bugs. The mist settles on open surfaces rather than penetrating harbourages, and the repellent effect drives bed bugs into hiding across a wider area.
What actually clears a bed bug infestation
Professional bed bug treatment works differently from a retail spray in three ways.
Professional products. BPCA accredited technicians have access to professional-use insecticides that are not available to the public, applied at the correct concentration and in the places bed bugs actually harbour.
A whole-room approach. Treatment covers the bed frame, mattress, surrounding furniture, skirting boards and the routes bed bugs use to move, not just the visible surfaces.
Steam, then a residual. Each affected room is steam treated, which kills bed bugs and their eggs on contact through heat. This is the step no retail product replicates, and it is why the egg problem that defeats sprays does not defeat professional treatment. A residual insecticide is then applied to harbourage areas, staying active for six to eight weeks so that any bed bugs hatching after the visit are dealt with as they emerge.
A 60 day guarantee. Bugwise treatment is backed by a 60 day guarantee, so if a second visit turns out to be required it is covered. Treating the whole cycle in one properly executed visit is the aim, rather than booking repeat visits as a matter of course.
Bugwise arranges treatment based on what you report seeing, and will advise on preparation before the visit. That preparation matters: washing affected bedding and clothing at the highest temperature the fabric can safely tolerate, sealing laundered items in bags, and pulling furniture clear of walls all help the treatment reach where it needs to.
What to Do Before Treatment
Preparation makes a measurable difference to how well a treatment works, because it clears the way to the places bed bugs actually harbour. The full bed bug treatment preparation checklist sets out what to do room by room. The essentials are:
- Wash affected fabrics at the highest temperature the items can safely tolerate, then seal them in bags until advised otherwise.
- Do not throw mattresses or furniture away without speaking to a pest controller first. Discarding items rarely solves the problem and can spread bed bugs through the property on the way out.
- Keep sleeping in the same room unless advised otherwise. Moving to another room or sofa draws bed bugs with you and spreads the infestation.
- Avoid spraying or fogging before the visit, for the reasons above.
Work through the preparation checklist before the appointment date, since a property that has been prepared properly gives the treatment the best chance of working first time.
Bed Bug Treatment Across East London and Essex
Bugwise provides BPCA accredited bed bug treatment for homes, landlords and businesses across Romford, Barking, Ilford, Dagenham, Hornchurch, Upminster and the surrounding areas. Bugwise is a Which? Trusted Trader and TrustMark approved, and treatment is arranged promptly based on what you have seen in the property.
Frequently Asked Questions
Share this Post
