Wasp Nest in a Cavity Wall – How Professionals Treat Hidden Nests in Belgrave
A steady line of wasps going in and out of one small opening usually means a nest is hidden behind the brickwork, and it needs treating from the outside.
One small opening, a steady stream of wasps
The clearest sign of a wasp nest in a cavity wall is not the nest at all. It is the traffic. If you watch an air brick, a weep hole or a gap in the pointing for a minute or two on a warm day and see wasps repeatedly slipping in and out, they are almost certainly heading to a colony inside the wall.
Single wasps wandering past a wall mean very little, because they are looking for food all summer long. What matters is the pattern. Wasps that arrive, vanish into the same spot and then reappear a minute later, always on the same flight path, are going home.
If you are in Belgrave and have noticed this at the back of the house or beside a patio door, resist the urge to poke at the opening or watch from close range. A live nest can hold thousands of wasps, and they defend the entrance if it is disturbed.
It helps to remember that wasps are creatures of routine. Each worker leaves to collect food or building material and comes back along much the same line. That is why a nest behind brickwork can be pinned down by patient watching even though nothing of the colony is visible. A quick glance is rarely enough, so give it a few minutes at different times of day.
What you can safely check from a distance
You can learn quite a lot without going near the wall. Stand back several metres, ideally from a window or across the garden, and note the following.
- Exactly where the wasps enter: an air brick, a missing piece of mortar, a gap beside a pipe or a join under the roof edge.
- How many are using the entrance in a minute, even as a rough impression such as a few or a constant stream.
- Whether they come and go from one spot only or from several gaps along the wall.
- Which room sits on the other side of that wall, and whether any wasps have appeared inside it.
- What time of day the flight path is busiest, since colonies are most active in warm, bright weather.
Write these down or take a photograph with the zoom on your phone. A clear description makes the booking call quicker and helps the technician plan the visit.
If you spot wasps indoors on the wall side, close the door of that room and leave the wasps alone rather than chasing them with a rolled-up newspaper. Any wasps you see inside are likely to be workers that have wandered out of the void by mistake, and fewer swats mean fewer stings.
Why an air brick makes such a good doorway
An air brick is a vented block built into the outer leaf of the wall so that air can move through the structure. To a queen looking for a sheltered, dry spot in spring, it is simply a ready-made hole that leads to a quiet space. Once she has found it she can start a small nest on a ledge or against an inner surface, and the colony grows from there.
Because the void is protected from wind and rain, the nest can keep expanding through the season. By August the colony is at its largest, and a nest can hold anything from 2,000 to 10,000 wasps or more. The opening that looked like a small nuisance in June can be carrying a very heavy load of traffic by late summer.
Warm walls make the situation worse. A sunny brick face heats the cavity behind it, and a warm void suits a growing colony very well, which is one reason the busiest entrances are often on sunny elevations of the house.
What a professional does about it
Treating a nest you cannot see is different from treating one hanging in a shed. The technician works through the entry point that the wasps are already using, because that is the route to the colony. You do not need to open up the wall, take out bricks or cut into plaster for this to be dealt with.
Our technicians are trained and fully insured, and they will look at the wall, confirm the entrance and treat the nest through it. We do not describe the exact method on this page, but you are welcome to ask any questions when you book. If you would like to know whether the empty nest can be taken down afterwards, ask at the time of booking.
It is normal to see a few wasps around the opening for a short while after the visit, so keep windows closed on that side of the house and keep children and pets indoors until the technician has told you it is fine.
Leave the opening alone until the visit is done
Please do not cover or fill the air brick or gap in the hope of trapping the wasps. Wasps that find their way blocked do not give up; they look for another route, and that route may be through the inside wall and into your living space. A wasp nest stuffed with filler outside has caused many a household to find wasps at a light fitting or skirting board.
Once the nest has been treated and the technician is satisfied, the opening can be repaired. Fitting a fine mesh over an air brick, or repointing a gap, makes it harder for another queen to move in next spring. Sealing is a job for after the treatment, never before it.
People sometimes ask whether a wire mesh pressed over the hole in the meantime would be acceptable. It is not. A mesh over an active entrance causes the same pile-up of wasps and the same search for another route, so wait until the colony has been dealt with.
Booking a visit
Wasp nest treatment is a fixed £95 per nest, and an additional nest on the same property is £35 per nest. There is no call-out charge. The price is confirmed on the phone before anyone comes out, and nothing is done until you have agreed. To arrange a visit, call 0116 214 9259 or use the online booking form on the contact page. We work seven days a week and offer same-day service for both homes and businesses.
If anyone in the household is allergic to wasp stings, tell us when you book so that we can take it into account.
Wasps on your property in Belgrave?
Fixed price £95 per nest, no call-out charge, same-day service available.