BC spiders you'll see indoors
Metro Vancouver sits in one of the most spider-rich temperate environments in North America. The Pacific Northwest's mild, wet winters allow many species to remain active year-round, and the urban environment provides abundant prey. Of the roughly 700 spider species recorded in BC, maybe a dozen regularly enter homes. Knowing which species you're dealing with is the first step in deciding whether to act.
| Species | Size (body) | Where seen | Concern level |
|---|---|---|---|
| European house spider (Tegenaria domestica) | 10-12 mm | Basements, crawlspaces year-round | Low — beneficial predator |
| Giant house spider (Eratigena atrica) | 15-20 mm | Basements, garages, fall migration | Low — beneficial predator |
| Cellar spider (Pholcus phalangioides) | 7-9 mm | Ceilings, corners year-round | Very low |
| Cross orb-weaver (Araneus diadematus) | 10-15 mm | Outdoor webs in fall | Very low — outdoor |
| Wolf spider (Lycosidae spp.) | 12-25 mm | Ground level, basements, garages | Low — no web, ground hunter |
| Jumping spider (Salticidae spp.) | 5-10 mm | Windows, sunny walls, perimeter | Very low — beneficial |
| False widow (Steatoda grossa) | 6-10 mm | Garages, basements, exterior corners | Low — bite possible but minor |
| Black widow (Latrodectus hesperus) | 8-10 mm female | Southern interior BC, rare in Metro Van | Medically significant |
Why most spider 'infestations' are seasonal
Late summer through fall (August–October), male European house spiders and giant house spiders leave their webs to find mates. This annual dispersal is the source of most BC homeowner spider complaints. Males abandon the funnel web they've occupied for months and begin walking in search of females — they're fast, large (giant house spiders regularly reach 15–20 mm body length), and appear in unexpected places: bathtubs, floors, beds, shoes. The phenomenon ends abruptly in November as nighttime temperatures drop. Most fall spider sightings don't represent an infestation — they represent the normal seasonal behaviour of a healthy outdoor population that has been quietly reducing your other pest load all summer.
The second most common seasonal pattern is late winter emergence of juvenile spiders from egg sacs laid the previous autumn. In January and February, homeowners occasionally notice dozens of tiny spiders on interior walls, especially near windows. These are hatchlings dispersing — they disperse rapidly and the event is usually over within 48–72 hours. Treatment is not indicated unless the source egg sac was indoors.
When spider treatment is warranted
- Heavy webbing in living spaces (not just basement corners) accumulating over multiple weeks despite regular cleaning.
- Visible egg sacs in occupied rooms — especially multiple sacs, which suggests established indoor breeding.
- Spider phobia (arachnophobia) interfering with daily home use — even if the population is technically within normal range, quality of life is a legitimate management goal.
- Confirmed medically significant species — western black widow in homes in the Lower Mainland is rare but documented; any confirmed sighting warrants treatment.
- Properties with persistent prey populations: if you have active silverfish, carpenter ants, or other indoor pests, spiders have a reliable food source and populations will be elevated accordingly.
- Commercial properties, food facilities, or sensitive-use buildings where any visible pests — including spiders — create compliance or liability concerns.
What treatment looks like — the Wild Pest protocol
Spider control protocol — Metro Vancouver residential
The four-stage approach we use for residential spider management. Whole-house spray is not part of this protocol — targeted application outperforms broad application and preserves the beneficial predator ecology.
- 1Inspection and source diagnosisWalk the full interior and exterior. Document active webs, egg sacs, prey sources (other pests), and structural access points. Note moisture readings in basement and crawlspace — high humidity drives prey and therefore spider concentration.
- 2Manual web and egg sac removalRemove all visible webs, including inactive ones. Sweep thoroughly in basement, garage, attic, and exterior eaves. This step alone produces an immediate visible improvement and removes overwintering egg sacs. Resets the 'clock' that helps monitor re-infestation rate.
- 3Targeted perimeter applicationApply registered pyrethroid product (deltamethrin or bifenthrin) to the foundation perimeter, basement perimeter, garage corners, and entry points. This is an 18–24 inch treatment band, not a full yard spray. Residual lasts 60–90 days. For fall pressure, schedule this application in late July to early August before the migration begins.
- 4Structural sealing — the part most services skipSeal gaps larger than 3 mm at door bottoms, window frames, foundation cracks, and utility penetrations. Stainless steel mesh wool packed into larger gaps, closed-cell foam over the top. This is NN-1 work: every service should include structural exclusion, documented in the photo report. See our [exclusion guide](/guide/spider-prevention-vancouver) for materials list.
What we don't do — and why
We don't fog homes for spiders. Pyrethroid fogging or whole-house indoor spray is an outdated technique that kills beneficial insects (including natural spider predators), distributes pesticide residue on food-contact surfaces, and doesn't produce better outcomes than targeted application. The BC Integrated Pest Management Act requires that pesticide application be the minimum necessary to achieve the management objective — not maximum application to maximize visible activity.
We also don't recommend ultrasonic repellers, essential oil sprays, or diatomaceous earth applied as a whole-room treatment. Diatomaceous earth has legitimate targeted uses (crawlspace perimeter, joist bays), but broadcasting it through living spaces creates respiratory dust and doesn't outperform the targeted pyrethroid protocol.
Integrated approach: the four levers
- Prey reduction: address silverfish, carpenter ants, or other indoor pests that sustain spider populations. See [silverfish control](/guide/occasional-invaders-vancouver) and [carpenter ant guide](/guide/carpenter-ants-bc).
- Structural exclusion: seal entry points before the August migration window. Our technicians document every gap in the photo report, so you have a record of what was treated.
- Lighting management: exterior lights attract flying prey insects, which attract spiders. Yellow-spectrum or motion-activated lights significantly reduce attraction.
- Timed perimeter treatment: one application in late July outperforms two reactive applications in September-October because it intercepts migrants before they enter rather than after.