Hornets

What hornets look like

Hornets are large social wasps, with workers commonly running 18 to 25 mm and queens larger again. The body is smooth rather than hairy, with a narrow waist and long legs that hang in flight. In Ontario the insect most people call a hornet is the bald-faced hornet, which is black with bold ivory white markings on the face and the end of the abdomen. European hornets also occur in parts of Southern Ontario and are brown and yellow with reddish shading. The nest is the other identifier: a grey papery envelope made from chewed wood fibre, often shaped like a teardrop or a football, with a single guarded opening near the bottom.

Signs you have hornets

• An aerial paper nest. A grey, layered envelope hanging from a tree branch, eave, soffit, shed roof, porch ceiling or dense shrub.
• A guarded entrance. Insects arriving and leaving through one hole near the base of the nest, with others stationed outside it.
• Steady high traffic. A consistent flight path along a wall or roofline to a single point, building through July and August.
• Warning behaviour. Hornets flying at your head, hovering in front of your face or making a sharp clicking sound as you approach an area.
• Stripped wood. Fine scraped lines on weathered fence boards, deck rails or garden furniture where nest material has been gathered.
• Scavenging in late summer. Large wasps working over bins, compost, fallen fruit and outdoor food later in the season.

Any nest near a door, walkway or work area should be treated as urgent rather than watched.

Why hornets turn up around Ottawa and Toronto properties

Hornets need three things, and Ontario properties supply all of them. First is a sheltered anchor point off the ground, which is what a soffit return, porch ceiling, shed eave, pergola, mature shade tree or thick cedar hedge provides. Second is wood fibre for building, and every weathered fence, deck rail and unpainted garden structure is a supply depot. Third is food: caterpillars and flies early in the season, then sugar from fallen fruit, recycling bins, outdoor dining and compost later on. The wooded ravines and mature tree canopy of the Toronto GTA, the older tree-lined streets of Ottawa and the escarpment edge in Hamilton all put nest sites close to houses. A colony starts small in spring with one queen and is largely unnoticed until the worker population climbs sharply in mid to late summer.

Are hornets dangerous?

Yes, and this is where hornets differ from bees. Hornets defend the nest aggressively and in numbers. Their sting is smooth, so a single hornet can sting repeatedly, and a disturbed colony will pursue a perceived threat well away from the nest. Vibration alone, such as a lawnmower, a hedge trimmer, a ladder against the soffit or a slammed door, is often enough to trigger a defensive response. Stings are painful for anyone and can be a medical emergency for a person with an allergy. Multiple stings are a serious matter regardless of allergy. Structural damage is limited, since the nest is made of paper and the insects do not bore into timber, but nests built inside a soffit, wall void or attic can stain surfaces, and abandoned nests draw in carpet beetles and other scavengers. Treating a hornet nest yourself is the wrong move.

How to keep hornets away

• Check eaves, soffits, sheds, porch ceilings, playhouses and dense shrubs in late spring and early summer while nests are still small.
• Seal gaps in soffit, fascia, siding and gable vents so a queen cannot build inside a wall or roof cavity.
• Keep bins closed and clean, rinse recyclables, and store compost in a sealed unit away from doors and patios.
• Clear fallen fruit from under trees promptly and keep outdoor food and sugary drinks covered from July onward.
• Paint or seal weathered fences, rails and garden furniture, which removes an easy source of nest building fibre.
• Move hummingbird feeders and sweet feeders away from seating areas and doorways, and keep them clean.

Removing a small early nest is straightforward, while a late summer nest takes proper equipment.

How GO! Pest Control handles hornets

• Inspection. We find the nest and confirm whether it is aerial or built inside a void, identify the species, and work out the flight path and the safest approach.
• Treatment. Hornets are aggressive near the nest, so this is not a relocation job. We treat the colony directly in full protective equipment, at the right time of day for safety.
• Removal. Once the colony is inactive we remove the accessible nest material so it does not attract scavenging insects or get reused as a marker site.
• Exclusion. We point out and close the soffit, vent and siding gaps that let a queen build inside the structure in the first place.
• Follow-up. We check for returning workers and for any second nest on the property, since more than one is common on larger lots.

We are licensed, insured and bonded, and we work in homes, apartments, condos and businesses across the Toronto GTA, Ottawa and Hamilton.

Common questions about hornets