Montreal Pest Library
Detailed profiles of the most common pests found in Montreal homes and businesses — identification, biology, health risks, and treatment options.
Showing 17 pests
CockroachesGerman Cockroach
Blattella germanica
The most common and difficult-to-eliminate cockroach species in Montreal apartments. Spreads through shared walls and plumbing in multi-unit buildings.
Norway Rat
Rattus norvegicus
The dominant rat species in Montreal. Burrows underground and enters homes through foundation gaps. Causes structural damage and transmits disease.
Carpenter Ant
Camponotus pennsylvanicus
Quebec's most destructive insect pest. Excavates galleries in moist wood, causing structural damage that can take years to become visible.
Bed Bug
Cimex lectularius
A blood-feeding parasite that hides in mattress seams and furniture. Spreads rapidly through apartment buildings and is resistant to many insecticides.
House Mouse
Mus musculus
The most common rodent pest in Montreal homes. Can squeeze through a 6 mm gap and reproduces rapidly once inside. Contaminates food and gnaws wiring.
Yellow Jacket
Vespula spp.
The most aggressive wasp species in Quebec. Builds paper nests underground and in wall voids. Colonies can reach 5,000 workers by late summer.
Pavement Ant
Tetramorium caespitum
The most common kitchen ant in Montreal. Nests under concrete slabs and enters homes seeking food. Forms visible trails along baseboards and counters.
Cellar Spider
Pholcus phalangioides
The most common spider in Montreal basements. Long-legged and harmless to humans. Builds loose, irregular webs in dark, humid spaces.
Black Widow Spider
Latrodectus variolus
Quebec's only medically significant venomous spider. Shy and reclusive, but its neurotoxic venom causes severe muscle cramps and systemic symptoms requiring emergency care.
Wolf Spider
Hogna carolinensis
Large, fast-moving ground hunters that invade Montreal homes every fall. Alarming in appearance but harmless — they follow insects indoors and do not build webs.
Yellow Sac Spider
Cheiracanthium mildei
The most common cause of indoor spider bites in Quebec. Roams walls and ceilings at night and bites when trapped against skin. Causes burning, slow-healing wounds.
Bald-Faced Hornet
Dolichovespula maculata
Builds large football-shaped paper nests in trees and on structures. Extremely aggressive when disturbed. Colonies reach 400–700 workers by late summer.
Boxelder Bug
Boisea trivittata
A classic fall invader — thousands aggregate on south-facing walls in October seeking warmth. Harmless but stain walls and release a foul odour when crushed.
Clothes Moth
Tineola bisselliella
The most destructive fabric pest in Montreal homes. Larvae silently devour wool, cashmere, silk, and fur in dark closets — often undetected until significant damage is done.
Carpet Beetle
Anthrenus verbasci
Commonly misdiagnosed fabric pest whose larvae destroy wool carpets, rugs, and clothing. Adults appear on windowsills in spring — a reliable sign of indoor breeding.
House Centipede
Scutigera coleoptrata
Alarming but completely harmless — a beneficial predator that eats cockroaches, silverfish, and spiders. Its presence signals moisture and an underlying insect population.
Millipede
Narceus americanus
Slow-moving detritivores that invade Montreal basements after heavy rain. Completely harmless — no biting, no structural damage — but large numbers are a nuisance.
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