Overview
Wolf spiders are among the most commonly encountered large spiders in Montreal homes, particularly in fall when they move indoors seeking warmth. Unlike most spiders, wolf spiders do not build webs to catch prey — they are active hunters that chase down insects on the ground. They are large, fast, and alarming in appearance, but are not medically significant and pose no real threat to humans. Their presence indoors almost always indicates an underlying insect population they are following.
How to Identify Wolf Spiders
- Body size: 10–35 mm depending on species — among the largest spiders encountered indoors in Quebec
- Colour: Brown, grey, or tan with darker stripes or mottled patterning — excellent camouflage
- Eyes: Eight eyes arranged in three rows — two large eyes in the middle row reflect light (eyeshine) when a flashlight is shone at them at night
- Body: Robust, hairy, with long powerful legs built for running
- Movement: Fast, ground-level runners — do not build webs
- Females: Carry egg sac attached to spinnerets at the rear of the abdomen
- Spiderlings: Females carry spiderlings on their back after hatching — a distinctive behaviour
- Habitat: Ground level — under furniture, along baseboards, in basements and garages
Biology & Behaviour
- Lifespan: Female 1–3 years; male typically 1 year
- Egg sac: Female carries a single egg sac containing 100–400 eggs attached to her spinnerets
- Spiderling care: After hatching, spiderlings climb onto the mother's back and are carried for 1–2 weeks
- Hunting method: Active pursuit — chases prey on the ground rather than using a web
- Diet: Insects, other spiders, and occasionally small vertebrates
- Activity: Primarily nocturnal; most active at night
- Seasonal pattern: Move indoors in September–October seeking warmth; most visible in fall
- Preferred habitat: Ground level in leaf litter, under rocks, in burrows, and along the edges of structures
Health Risks
- Bite: Wolf spiders can bite if handled or cornered, but bites are uncommon
- Venom: Mildly venomous — causes localized pain, redness, and swelling similar to a bee sting
- No systemic effects: Wolf spider venom does not cause systemic symptoms in healthy adults
- Not medically significant: Wolf spiders are not considered a medical threat in Quebec
- Psychological impact: Their large size and speed make them alarming, but they are harmless
- Beneficial: They are effective predators of insects including cockroaches, crickets, and other pests
Signs of Presence
- The spider itself — large, fast-moving, ground-level, often seen at night
- Eyeshine: Shine a flashlight at ground level at night — wolf spider eyes reflect light with a distinctive green glow
- No webs: Unlike most spiders, wolf spiders do not build webs — their absence is a key identifier
- Egg sac: Female carrying a round, white egg sac attached to her rear
- Spiderlings: Female carrying dozens of tiny spiderlings on her back
- Common locations: Basements, garages, ground-floor rooms, under furniture, along baseboards
Prevention
- Seal gaps under doors, around utility penetrations, and through foundation vents — wolf spiders enter at ground level
- Install door sweeps on all exterior doors, including the garage door
- Reduce outdoor lighting near the house — lights attract the insects that wolf spiders hunt
- Keep basements and garages organized — eliminate clutter that provides hiding spots
- Address underlying insect problems — wolf spiders follow their food source indoors
- Reduce moisture in basements — high humidity attracts the insects wolf spiders eat
- Trim vegetation and remove leaf litter from around the foundation
Professional Treatment
Wolf spiders rarely require professional treatment. Sealing entry points and reducing the underlying insect population are the most effective long-term solutions. If wolf spider populations are high, professional exterior perimeter spray and interior crack-and-crevice treatment can significantly reduce numbers. Individual spiders found indoors can be captured and released outside. Call 514-809-1999 for a free inspection if wolf spider activity is persistent.