Wasp Season in Montreal: When to Watch Out and How to Stay Safe

Wasp season in Montreal follows a predictable pattern that begins with a single queen in spring and ends with hundreds of aggressive workers by late summer. Understanding this timeline helps you spot problems early, avoid dangerous encounters, and know exactly when to call for professional removal. This guide covers the complete wasp season in Montreal — from the first queens in May to the final workers in October.

May: The Queens Emerge

Wasp season begins in early to mid-May when fertilized queens emerge from hibernation. These queens have survived the winter in protected locations — under bark, in wall voids, or in attics. Each queen begins building a small nest, laying eggs, and foraging for food to feed her first batch of workers.

Nests at this stage are tiny — about the size of a golf ball — and contain only the queen and a few developing larvae. This is the ideal time for removal, but nests are often hidden and difficult to locate. Watch for queens scouting locations under eaves, in sheds, and around deck structures.

June: Colony Establishment

By June, the first workers have emerged and taken over foraging duties. The queen now stays in the nest laying eggs while workers expand the structure and gather food. Nests grow rapidly — from golf ball to tennis ball size within weeks.

You may notice increased wasp activity around your property as workers scout for food. They are particularly attracted to protein sources in early summer to feed developing larvae. Outdoor grilling, pet food, and garbage become attractants.

July: Peak Nest Growth

July is when wasp nests reach their most visible stage. The structure is now the size of a grapefruit or larger, with dozens of workers coming and going. Nests are typically located under eaves, in attics, in sheds, or hanging from trees and shrubs.

This is the best time for professional removal — nests are large enough to locate easily but have not yet reached maximum population. Yellow jacket nests in ground holes become noticeable as workers create a visible entrance hole.

August: Maximum Aggression

August is peak wasp season in Montreal. Colonies have reached maximum size — 200 to 5,000 workers depending on the species and nest location. Nests are now the size of a football or larger.

Worker wasps become increasingly aggressive in late summer for two reasons: first, the colony is at maximum population and workers are competing for resources; second, the diet shifts from protein to sugar, bringing wasps into conflict with humans at picnics, barbecues, and outdoor dining areas.

September: The Decline Begins

As temperatures cool and food sources diminish, wasp colonies begin to decline. New queens and males are produced for mating, after which the colony will die off. However, wasps become more aggressive, not less, as they compete for scarce resources.

September is when wasps are most likely to crash outdoor events, swarm garbage bins, and enter homes seeking food. Nests are still active and dangerous, though the colony is beginning to break down.

October: Season End

By mid-October, most wasp colonies have collapsed. Workers die off, and fertilized queens seek shelter to hibernate through winter. You may see sluggish wasps on warm days, but active nests are rare after Thanksgiving.

This is the time to inspect your property for old nests and seal entry points before next spring. Wasps do not reuse old nests, but queens may return to the same area to build new ones.

Wasp Species in Montreal

Different wasps have different behaviors and nesting preferences:

• Yellow jackets (Vespula spp.): Build paper nests underground or in wall voids. Most aggressive species. Nests can contain 5,000+ workers.
• Bald-faced hornets (Dolichovespula maculata): Build large football-shaped nests in trees and on structures. Extremely aggressive when disturbed.
• Paper wasps (Polistes spp.): Build open umbrella-shaped nests under eaves. Less aggressive but will sting if nest is touched.
• European hornets (Vespa crabro): Large hornets that nest in hollow trees and wall voids. Active at night, unlike other wasps.

When to Call for Professional Removal

Call Blackline Pest Control immediately if:

• The nest is larger than a tennis ball
• The nest is located near a doorway, walkway, or high-traffic area
• Anyone in your household has a wasp venom allergy
• The nest is inside a wall void or attic
• You have been stung near the nest — this indicates the colony is already defensive
• The nest is underground (yellow jacket nests) — these are particularly dangerous

Our wasp removal service includes safe treatment of the nest, physical removal, disposal, and application of residual insecticide to prevent re-establishment. We offer same-day emergency service for dangerous nest locations. Call 514-809-1999 for immediate assistance.