SEASONAL REFERENCE
Quebec pest calendar
Every pest has its season. Knowing when a species enters, breeds or turns aggressive lets you act at the right moment — often well before the problem is visible.
The three annual peaks in Quebec
May
Ants (pavement and field)
Winged ants indoors indicate a mature colony established for several years. Have the framing inspected.
August
Wasps
Highest sting-risk month. Never handle a mature nest yourself, especially with an allergic person in the household.
October
Mice
Act at the first signs: 3 to 6 mm droppings, night scratching noises, gnawed packaging.
Month by month
January
WinterPests active in winter are those living indoors year-round. Heating maintains an ideal temperature for cockroach reproduction, and mice already established in walls breed without interruption.
What to do: Inspect warm, damp areas: behind appliances, under the sink, around plumbing.
February
WinterCold drives rats closer to heated buildings and underground networks. It's also when damage from gnawed electrical wires becomes noticeable.
What to do: Check the basement and garage: fresh droppings, night noises, gnaw marks.
March
SpringThe first carpenter ant workers emerge from diapause as soon as the structure warms. Seeing ants indoors in March, while it's still freezing outside, almost always signals a nest inside the building.
What to do: Any ant seen indoors in March warrants an inspection: the nest is in the structure, not outside.
April
SpringFertilized wasp queens emerge from hibernation and look for a nesting site: eaves, soffits, sheds, wall cavities. A nest destroyed at this stage contains a single individual.
What to do: This is the best time of year for wasp prevention: inspect and seal openings before nests form.
May
SpringPEAKCarpenter ant swarming peaks: winged individuals appear, often near windows. Pavement ants start invading kitchens in search of sugar.
What to do: Winged ants indoors indicate a mature colony established for several years. Have the framing inspected.
June
SummerFlea season starts with the heat: the egg-to-adult cycle accelerates and pets bring fleas in from outdoors. Wasp nests reach the size of a tennis ball.
What to do: Start or maintain veterinary flea treatment for your pets — far simpler than treating an established infestation.
July
SummerWasp colonies grow rapidly and become visible. Fleas reach peak reproduction: a female lays up to 50 eggs a day, which fall into carpets and bedding.
What to do: Have wasp nests removed now, while they are still small and the colony less aggressive.
August
SummerPEAKAnnual wasp peak. Colonies reach maximum size (several hundred individuals) and, as sweet food sources dwindle, wasps become markedly more aggressive toward humans.
What to do: Highest sting-risk month. Never handle a mature nest yourself, especially with an allergic person in the household.
September
FallSeason pivot: wasps are at their most aggressive while rodent migration begins. At the first cold nights, mice and cluster flies actively seek to enter buildings.
What to do: Ideal time for preventive sealing: seal cracks, garage door bottoms and dryer ducts before the cold arrives.
October
FallPEAKAnnual peak of rodent entry. A mouse squeezes through a 6 mm opening (a dime) and a rat through about 2 cm. This is the month when most residential mouse infestations begin in Quebec.
What to do: Act at the first signs: 3 to 6 mm droppings, night scratching noises, gnawed packaging.
November
FallRodents that entered in October are now established and breeding in walls and attics. A single female can produce 4 to 8 litters a year, of 6 to 12 pups each.
What to do: Don't put it off until spring: every month of delay multiplies the population and the damage.
December
WinterHoliday travel (hotels, visits, luggage) makes December a high-risk month for introducing bed bugs. They travel by clinging to luggage and clothing.
What to do: After travelling, inspect your luggage and wash all clothing at 60 °C before putting it away.
Are you in the risk season?
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