Wasp and Hornet Nest Identification in Ontario (2026): Types, Photos & What to Do

Last updated: July 24, 2026

Quick answer: In Ontario, an open honeycomb “umbrella” under an eave is a paper wasp nest, a grey basketball-shaped nest high in a tree is a bald-faced hornet nest, and a hidden nest in the ground or a wall void is usually a yellowjacket. By late summer a single yellowjacket colony can hold thousands of workers, so a nest near your home is not something to tolerate — it’s something to remove. Sani IQ identifies and removes stinging-insect nests across Ontario.

You spot a swirl of activity under the eaves, or a grey papery ball hanging from a branch, and the questions come fast: What is it? How dangerous is it? Do we still let the kids play back there? Correct wasp and hornet nest identification is the first step, because the type of nest tells you how aggressive the colony is, where the rest of it might be hiding, and how urgent removal really is. Right now, in the mid-to-late summer peak, Ontario nests are at their largest and most defensive of the entire year — which is exactly when accurate identification matters most.

Wasp and hornet nest types at a glance

Before you get anywhere near a ladder, match what you’re seeing to the table below. The nest’s shape and location usually identify the species faster than the insect itself.

Nest feature	Paper wasp	Yellowjacket	Bald-faced hornet
Nest shape	Open honeycomb / upside-down umbrella	Enclosed grey “paper bag,” one bottom entry	Large grey teardrop, up to basketball-sized
Cells visible?	Yes — exposed hexagonal cells	No — hidden by an outer shell	No — hidden by a multi-layer paper shell
Typical location	Under eaves, deck railings, door frames, sheds	Underground burrows, wall voids, attic cavities	High in trees, tall shrubs, roof peaks
Peak colony size	20–75 wasps	Up to several thousand workers by August	Roughly 100–400 by late summer
Temperament	Moderate, defensive if touched	Very aggressive, swarms when disturbed	Highly territorial near the nest
What to do	Keep clear; book removal	Do not disturb; book removal fast	Keep well back; book removal

How do I identify a paper wasp nest?

A paper wasp nest looks like a small, open honeycomb hanging upside-down like an umbrella, with the hexagonal cells fully visible because there’s no outer covering. You’ll find them under eaves, deck railings, door frames, and inside open sheds — anywhere with overhead shelter and a horizontal surface.

Paper wasps are the most common stinging insect around Ontario homes and generally the least aggressive of the three. They won’t usually bother you unless you touch the nest or crowd it directly. The catch is location: a paper wasp nest tucked beside a frequently used door, a patio, or a child’s play structure turns an otherwise mild species into a genuine daily hazard. The nests are small early in the season and easy to miss until the colony has grown.

How do I identify a yellowjacket nest?

Yellowjacket nests are enclosed in a grey, papery shell with a single entry hole at the bottom, and they’re usually hidden — underground in old rodent burrows, behind brickwork, or inside wall and attic voids. Because the nest is concealed, people often find it by accident, which is when stings happen.

This is the nest type to take most seriously. Yellowjackets are responsible for the majority of “unprovoked” late-summer stings in Ontario, and they swarm aggressively when the nest is disturbed — even the vibration of a passing lawnmower can trigger an attack on a ground nest. Their numbers are the real story: according to Ohio State University Extension, a yellowjacket colony can reach roughly 4,000 to 5,000 workers with 10,000 to 15,000 cells by late summer, and Cornell IPM reports colonies growing to 5,000 workers or more by season’s end. A nest that size inside a wall void beside your bedroom is not a minor problem.

How do I identify a bald-faced hornet nest?

A bald-faced hornet nest is a large, grey, teardrop-shaped paper nest — often as big as a basketball — hanging high in a tree, tall shrub, or under a roof peak. The tough, multi-layered shell is made from chewed wood fibre mixed with saliva, and it’s almost always well off the ground.

Bald-faced hornets are technically a type of large yellowjacket, and while their colonies are smaller — the PestWorld pest guide notes peak populations of roughly 100 to 400 members, with nests reaching up to 14 inches across and more than 24 inches long — they are intensely protective of the nest. They post guards at the entrance, can sting repeatedly, and will defend a wide radius. A nest overhanging a driveway, deck, or walkway is a removal job, not a wait-and-see one.

What should I do if I find a nest on my property?

Keep everyone well clear, identify the nest type from a safe distance, and book a licensed operator — do not spray it or knock it down yourself. Here’s the order of operations that keeps you safe and gets the nest gone:

1. Mark and avoid the area. Keep kids and pets away, and note where the activity is heaviest — especially for hidden ground or wall nests.
2. Identify from a distance. Use the table above. Do not lean in for a close look or shine a light into the entry hole.
3. Don’t disturb it. Raking, poking, or vibrating a nest triggers a mass stinging response. This is the single most common way Ontario homeowners get stung.
4. Skip the store-bought spray. Retail sprays often kill only surface insects and can drive a wall-void colony deeper into your home instead of out.
5. Watch for allergy signs. Hives, swelling away from the sting site, or any breathing difficulty needs immediate medical care.
6. Book a licensed Ontario operator. A pro confirms the species, treats the colony at the source, and removes the nest safely.

Why DIY nest removal goes wrong

Store-bought sprays reach the insects you can see but rarely the queen and larvae protected inside, so the colony rebuilds — and the act of spraying provokes exactly the swarm you’re trying to avoid. DIY removal is best understood as a time-and-risk trade, not a saving.

The honest comparison:

	DIY removal	Sani IQ (licensed)
Reaches queen & larvae	Rarely	Treated at the source
Sting risk to you	High — you’re disturbing the nest	Handled by a suited technician
Wall-void nests	Spray can drive them indoors	Treated and drawn out safely
Your time	Repeat evenings, no guarantee	One booking, then it’s handled
Lasting result	Colony often rebuilds	Backed by our guarantee

Spraying a concealed yellowjacket nest inside a wall is the classic mistake: the colony retreats into the house rather than out of it, and a few days later they’re finding their way through light fixtures and outlets into living space.

What this means for Ontario homeowners in 2026

Ontario’s wasp and hornet colonies follow a predictable arc: queens start small nests in spring, and populations build steadily to their peak in August and September. That means nests you barely noticed in June are now at their largest and most defensive. In a well-kept home, an active nest near a door, deck, or play area isn’t part of a normal Ontario summer — it’s a hazard with a clear fix.

Sani IQ removes stinging-insect nests across the province, including wasp removal in Whitby and Durham, and pest control in Orillia and Lake Country. In the western GTA we handle targeted jobs like wasp nest removal in Oakville. If you want to go deeper on stinging-insect biology and control, see our complete Ontario wasps and hornets field guide, and if you’re trying to tell the insects themselves apart, our guide to wasp vs hornet vs yellowjacket in Ontario breaks it down. Wasp nest removal with Sani IQ starts from $247.

Why Sani IQ

Sani IQ is a licensed, science-based Ontario pest-control company. We identify the species before we treat, use professional protective equipment and high-reach tools to work nests safely from the ground, and apply residual barriers that discourage scout wasps from rebuilding in the same spot. We’re owner-operated, fully licensed and insured, and trusted with 126 five-star reviews from homeowners across the GTA, Barrie, and Simcoe County — every job backed by our Pest-Free, OR It’s Free guarantee.

The bottom line

The nest’s shape and location tell you almost everything: open umbrella means paper wasp, hidden grey shell means yellowjacket, big grey teardrop up high means bald-faced hornet. All three warrant removal when they’re close to where your family lives — and by late summer, the colonies are only getting bigger. Don’t gamble with a ladder and a can of spray.

Call Sani IQ at (705) 302-1887 or request a quote at /contact/. Book it and forget about it.

Frequently asked questions

How can I tell a wasp nest from a hornet nest? Look at shape and height. Paper wasp nests are small, open honeycombs under eaves; yellowjacket nests are hidden grey “paper bags” in the ground or walls; bald-faced hornet nests are large grey teardrops hanging high in trees or under roof peaks. Location and nest structure identify the species faster than the insect does.

Which nest is the most dangerous in Ontario? Yellowjacket nests are generally the most dangerous because they’re hidden, easily disturbed, and hold the most insects — up to several thousand workers by late summer, per Ohio State University Extension. They swarm aggressively and cause most late-season stings. Bald-faced hornets are smaller in number but fiercely protective of the nest.

Can I remove a wasp nest myself? You can, but it rarely ends well. Store-bought sprays often miss the queen and larvae, the colony rebuilds, and disturbing the nest triggers a swarm. Wall-void nests can be driven deeper into your home. For most homeowners, DIY is a time-and-risk trade, not a saving — a licensed operator is safer and lasts.

What time of year are wasp and hornet nests biggest in Ontario? Colonies build all summer and peak in August and September, when yellowjacket nests can hold thousands of workers. Nests are smallest and easiest to treat in early summer, which is also the cheapest time to remove one. By late summer, an active nest near your home warrants prompt professional removal.

Do wasps reuse old nests the next year? No. Ontario paper wasps, yellowjackets, and bald-faced hornets build a fresh nest each year; the old one is abandoned over winter. But a good location tends to attract new queens the following spring, which is why Sani IQ applies residual barriers to discourage rebuilding in the same spot.

What should I do if a nest is inside my wall? Don’t spray it — that can push the colony further into your home. Keep the area clear, avoid the entry point, and book a licensed operator. A pro can treat a concealed nest so the insects are drawn out and eliminated safely rather than trapped inside your walls.