Wasps in Your Walls: Why You're Hearing Buzzing Inside (and Why You Should Never Seal the Hole)

Quick answer

Buzzing inside a wall in late August almost always means a yellowjacket or paper wasp colony has built its nest inside a wall void — behind siding, brick veneer, or soffit — and the colony is now at its largest size of the year. Do not seal the entry hole. Trapped wasps chew laterally through drywall and end up inside your living space. Have the nest treated first, then seal the gap once the colony is confirmed dead. Sani IQ wasp and nest removal is $247 per nest for standard access, and every job starts with a $95 inspection that is credited in full when you book the treatment. Call (705) 302-1887.

If you are standing in a quiet room in Mississauga or Vaughan right now hearing a low, papery hum coming out of a wall, you are not imagining it, and you are not early. You are late. A wall-void nest that becomes audible in the third week of August has usually been building since June.

Here is what is actually happening behind that drywall, and the one mistake that turns a $247 problem into a drywall repair.

How a wasp nest ends up inside your wall

Wall-void nests do not start as wall-void nests. They start as a queen looking for a dry, dark, undisturbed cavity in late spring.

In May and early June, an overwintered yellowjacket queen inspects your exterior for an opening about the width of a pencil. She is not fussy. The gaps she finds on a typical Ontario home are always the same short list:

• The seam where vinyl siding meets a window frame or corner post
• Weep holes and mortar gaps in brick veneer
• Unscreened soffit and roof vents
• The gap around a dryer vent, hose bib, or utility penetration
• A lifted piece of aluminum capping on a bay window
• Gaps behind fascia board where the wood has cupped

She squeezes through, finds the insulated cavity behind it, and starts a nest the size of a golf ball. Through June and July the colony grows quietly, and the insulation muffles it. By mid-August a mature yellowjacket colony can hold several thousand workers, and the traffic in and out of that pencil-width hole becomes constant enough that you finally notice it.

That is why the calls spike now. The nest was always there. It just got loud.

The sealed-hole trap

This is the single most expensive mistake homeowners make, and it is completely intuitive, which is why so many people make it.

You find the hole. You watch wasps go in and out. Sealing it seems obvious — caulk it at dusk, cut off the traffic, problem over.

What actually happens: a colony of several thousand wasps does not suffocate. It is sitting inside a cavity made of paper-faced drywall, batt insulation, and wood. When the exterior entrance closes, the colony does what it evolved to do — it chews toward light and airflow in a different direction. Very often, the shortest path is the interior drywall of the bedroom or hallway on the other side.

We have opened up walls where the wasps had already chewed through the paper facing and were an eighth of an inch from the room. Homeowners in that situation are dealing with a nest, a wall repair, and wasps loose in a bedroom at 2 a.m., instead of a treatment they could have booked that morning.

Order of operations matters: treat first, confirm the colony is dead, then seal. Health Canada’s guidance on wasps makes the same point about not disturbing an active nest without a plan.

How to tell it is a wall nest and not something else

Buzzing in a wall is not the only thing that makes noise in an Ontario wall cavity in August. A quick differential:

It is likely wasps if:

• The sound is a steady, papery hum that rises and falls with the sun — loudest on warm afternoons, near-silent on a cool night
• You can find a spot on the exterior with continuous two-way insect traffic, all going to the same point
• There is a faint damp or greasy staining spreading on the interior drywall or ceiling (nest moisture and larval material)
• The wall feels warm to the back of your hand compared to the wall two feet over
• Wasps occasionally appear inside the room near a baseboard, outlet, or light fixture with no open window nearby

It is probably not wasps if: the noise is scratching or gnawing rather than humming (rodents), it happens mainly at night and stops at dawn (mice, squirrels), or it is a dry rustling with no exterior insect traffic.

If you are unsure which stinging insect you are dealing with in the first place, our complete field guide to wasps and hornets in Ontario covers identification, aggression levels, and seasonal behaviour.

Where these show up across the GTA

The pattern varies by housing stock, and it is consistent enough to predict.

In Mississauga, the 1970s–1990s brick-veneer subdivisions through Erin Mills, Meadowvale and Streetsville produce a steady run of weep-hole and brick-gap nests, and the two-storey stucco and stone-front builds in Churchville and Lisgar tend to produce soffit and capping nests high up. Our Mississauga pest control team works these every August.

In Vaughan, the newer Maple, Kleinburg and Vellore Village stock skews toward vinyl and engineered siding, and the failure point is almost always a seam or a J-channel behind a corner post. Our Vaughan service area sees a large share of second-storey nests, which matters for access and cost.

Why spraying into the void does not work

Consumer wasp sprays are built for one job: knocking down a visible, exposed nest from a distance. That is a fair tool for a small paper wasp nest under a porch rail.

A wall void defeats it for three reasons. You cannot see the nest, so you cannot direct the product at it. The nest often sits several feet lateral or vertical from the entry hole, following the cavity, so the entrance tells you almost nothing about where the colony actually is. And a partial dose makes an active colony defensive without killing it — the wasps that come back out are looking for whatever caused it, which is usually the person on the ladder. Aerosol also soaks insulation, which is how you get a lingering odour problem in the room on the other side.

We wrote about the broader DIY-versus-professional tradeoff in can you remove a wasp nest yourself, and a wall void is the clearest case on the “do not” side of that line.

What professional wall-void removal involves

A proper wall-void job is not a can of spray pointed at a hole.

Our licensed technician starts by locating the actual nest rather than the entrance — tracking flight lines, checking interior temperature differentials, and reading the staining pattern. From there the treatment is applied into the void itself with equipment that reaches where the colony is, using reduced-risk products applied under the Ontario Pesticides Act.

The colony is then left to collapse over the following days as returning foragers carry the treatment inward. Sealing happens after that, not during it. Sealing a treated void too early is the same mistake as sealing an untreated one.

All of our technicians are employed, licensed and background-checked, and Sani IQ carries $5M liability coverage. We are BBB Accredited with a 5.0 rating across 126 Google reviews, and registered with the Ontario Ministry of the Environment, Conservation and Parks.

What it costs, and the part most homeowners get wrong

Wasp and nest removal is $247 per nest for standard access. If the nest requires extension-ladder or roof access — which second-storey soffit nests in Vaughan often do — that is quoted to you before any work starts, never after. Every service begins with a $95 professional inspection, credited in full when you book the treatment. One-time services carry a 60-day guarantee.

Now the part worth thinking about carefully.

Removing this year’s nest solves this year’s nest. It does nothing about the gap that let a queen in, and next May a different queen will inspect the same wall. Homes that get one wall-void nest tend to get another, because the entry conditions have not changed.

That is why we treat the one-time removal as the entry point and year-round protection as the actual answer. Our Insect Control plan is $845 per year and covers scheduled exterior treatments that intercept queens during the spring establishment window — before a nest exists to remove. Compare that against one wall-void nest at $247 plus the drywall repair, insulation replacement and repainting a chewed-through cavity requires, and the arithmetic is not close.

Start here: take the free quote quiz for a fast estimate on your specific situation, or review the plans and pricing page to see how the annual coverage compares to one-off callouts. If you want the nest handled today, call (705) 302-1887 — and if you are in Peel, our wasp nest removal in Mississauga page has the local details. You can also see our full wasp and hornet nest removal service.

Frequently asked questions

Will the wasps in my wall die off on their own in the fall? The workers will. Ontario yellowjacket colonies collapse after the first hard frosts and the nest is not reused. But that is six to ten weeks away — six to ten weeks of an active colony at peak size and peak defensiveness inside your wall — and the abandoned nest material left behind can attract carpet beetles and hold moisture. Waiting it out is rarely cheaper.

Can I just seal the hole in November after they are gone? Yes, and you should. Once the colony is confirmed dead, sealing that gap is one of the highest-value hours you will spend on your house. Seal in the fall, not in August.

Wasps are appearing inside my bedroom but I see no nest. What is that? That is the classic signature of a wall or ceiling void nest with an interior breach — often at a light fixture, an outlet box, or a gap where the wall meets the ceiling. It usually means the colony has already found a path toward the living space, and it should be treated promptly rather than watched.

Is the treatment safe around kids and pets? We use reduced-risk products applied by licensed technicians under the Ontario Pesticides Act, with re-entry guidance given for your specific application. Your technician will walk you through it before starting.

Do you cover my area? Sani IQ serves the GTA, York Region, Durham, Simcoe County, Barrie, Orillia and Muskoka. Call (705) 302-1887 and we will confirm scheduling for your address.