Identification
Latrodectus hesperus is the only Latrodectus species native to BC and the only medically significant spider in the province. Females are 8 to 15mm in body length with a glossy jet-black cephalothorax and abdomen and a bright red hourglass marking on the ventral (underside) surface of the abdomen. The hourglass is the diagnostic field sign — no other BC spider has it. Males are smaller (3 to 5mm), lighter-coloured, and not medically significant. Juveniles are striped or mottled and develop adult colouration over multiple molts. Webs are irregular three-dimensional tangles built close to the ground, often among debris, in window wells, under outdoor furniture, or in the eaves of sheds. The species is easily confused with the common house spider by homeowners who don't know the hourglass check.
Habitat in BC
Western black widow distribution in British Columbia is discontinuous. The species is common in the Okanagan, Kootenays, and Similkameen — arid southern Interior habitat that suits it. In Metro Vancouver proper, confirmed sightings are uncommon; the coastal wet climate is not ideal for the species. However, documented Lower Mainland occurrences do exist, particularly in warmer drier microclimates — south-facing foundations, stone-retaining walls in Surrey and Langley, older industrial-site debris in New Westminster and Delta, and occasionally imported via outdoor nursery-plant shipments from Okanagan suppliers. Residential Fraser Valley sightings in Abbotsford, Chilliwack, and Hope are not unheard of. Any BC homeowner should know the identification regardless of geography.
Signs you have western black widow
- A glossy black spider, 8–15mm body, with a bright red hourglass on the underside — the single diagnostic field sign.
- Irregular low-placed webs in debris piles, under outdoor furniture, in window wells, or inside rarely-accessed garden sheds.
- Webs that are unusually strong and 'crackly' when disturbed — Latrodectus silk is noticeably tougher than common house-spider silk.
- Egg sacs that are off-white, tan, or grey, roughly pea-sized, with a distinctly papery texture (unlike Parasteatoda sacs).
- The spider retreating rapidly when disturbed — Latrodectus is not aggressive but will bite if cornered or crushed.
Risk & damage
Western black widow venom is the most medically significant in any BC spider. A confirmed Latrodectus hesperus bite can cause latrodectism: intense localised pain radiating outward, muscle cramping (particularly abdominal), sweating, elevated blood pressure, and in severe or untreated cases (rare) more serious systemic effects. Fatalities from L. hesperus bites are extremely rare — modern antivenin and supportive care are effective — but the bite is genuinely medically serious and any confirmed bite warrants same-day medical evaluation at an emergency department. Children, elderly individuals, and those with pre-existing cardiovascular conditions are at higher risk. The BC Drug and Poison Information Centre (1-800-567-8911) is the resource for suspected spider bites.
Seasonality in Metro Vancouver
Western black widow activity in BC is strongly seasonal. Outdoor populations in suitable habitat are active April through October, with peak activity July through September. Females overwinter as adults in sheltered sites; egg sacs produced in summer hatch through fall. In Metro Vancouver's wetter coastal climate, the species overall is marginal — populations do not sustain the way they do in the Okanagan. The few Metro Vancouver sightings we've confirmed in recent years have been in warmer south-facing foundation microclimates during summer heat domes (the 2021 BC heat dome produced a noticeable bump in confirmed reports). Winter sightings in Metro Vancouver are essentially zero.
Treatment approach
Suspected Western black widow situations warrant a professional confirmation inspection before any treatment. We confirm species identification (many homeowner 'black widow' reports turn out to be Parasteatoda house spiders or Steatoda false widows). For confirmed L. hesperus populations, treatment uses targeted residual pyrethroid application at the specific harbourage plus physical removal of webs and egg sacs, with follow-up inspection at 30 and 60 days to confirm no re-establishment. Because the species is habitat-dependent, we also recommend site modifications: clearing debris piles, organising garden-shed storage, sealing low foundation gaps, and maintaining perimeter vegetation clearance. The service is priced at our spider-treatment rate ($245 base); the quarterly plan is appropriate for ongoing monitoring in the rare Metro Vancouver properties with confirmed populations.
When to call a professional
Call immediately on any suspected sighting in Metro Vancouver — confirmed L. hesperus populations in the Lower Mainland are uncommon enough that professional confirmation is warranted, and a true Western black widow presence in your home is a real medical concern. Photograph the spider (from a safe distance) before any attempted removal. For a confirmed bite, go to an emergency department or call 811 (HealthLink BC) immediately — this is not a DIY situation.
Prevention playbook
How to prevent western black widow in Metro Vancouver homes
- 1
Wear gloves in outdoor storage
Black widows favour dark, undisturbed dry locations: sheds, garages, crawlspace edges, under outdoor furniture, behind meter boxes. Wear leather or thick gardening gloves when reaching into these spaces.
- 2
Inspect outdoor seating and equipment before use
Lawn chairs, hose reels, garden tool handles, and barbecue covers can host widows. Shake out and visually inspect before use each spring.
- 3
Declutter garages and basements
Reduce corners, stacked boxes, and undisturbed piles. Black widows require inactive harbourage — active, cleaned spaces drive them away.
- 4
Seal exterior gaps + install door sweeps
Widows occasionally enter garages and ground-floor storage through exterior gaps. Seal foundation cracks and install door sweeps on garage and basement entries.
- 5
Treat any suspected bite as a medical emergency
Western black widow (Latrodectus hesperus) bites require medical evaluation. Symptoms can be delayed. If bitten, apply ice and go to emergency — do not wait to see if it worsens.
The Wild Pest service
See our Western Black Widow treatment page
Transparent pricing, 60-day return guarantee, same-day response across Metro Vancouver. Every treatment is documented with photos and service notes.
Frequently asked questions about western black widow
Do black widows actually live in Vancouver?+
Occasionally, but they are uncommon. Confirmed Metro Vancouver Latrodectus hesperus sightings are uncommon enough that each one is noteworthy; the species is much more established in the Okanagan, Kootenays, and Similkameen where the arid climate suits it. Lower Mainland confirmed reports are most often in Fraser Valley (Abbotsford, Chilliwack), occasionally in warmer microclimates of Surrey, Langley, and Delta. Vancouver proper is marginal habitat.
What do I do if I find one?+
Don't touch it. Photograph it from a safe distance, note the exact location, and call for professional confirmation. If you have children or pets in the home, move them away from the area until confirmed and treated. For a suspected bite, go to the nearest emergency department or call 811 (HealthLink BC) immediately. BC Drug and Poison Information Centre (1-800-567-8911) is the provincial resource for spider-bite assessment.
How dangerous is the bite?+
Medically serious but rarely fatal with modern care. A confirmed Latrodectus hesperus bite produces latrodectism — intense localised pain, muscle cramping, sweating, and systemic symptoms lasting 24 to 72 hours without treatment. Fatalities are extremely rare in modern BC; antivenin and supportive care are highly effective. Children, elderly adults, and people with cardiovascular conditions are at higher risk. Never dismiss a suspected bite — always seek same-day medical evaluation.
What does the red hourglass actually look like?+
Bright red (occasionally orange-red) shaped like two triangles meeting at their points, on the underside (ventral surface) of the abdomen. You have to either flip the spider (don't) or look up at it from below. Adult females have the most distinct hourglass; juveniles and males show variable markings. No other BC spider has this marking — if you see a glossy black spider with a red ventral hourglass, it is Latrodectus hesperus until proven otherwise.
Could the ones in my garage be from imported plants?+
Possibly, yes. One documented pathway for Latrodectus hesperus in Lower Mainland properties is outdoor nursery-plant shipments from Okanagan suppliers — the species can arrive as adults or egg sacs in pots or hanging baskets. If you have plants imported from the Interior and find a suspected black widow, it is worth a professional inspection of the planting area. Garden centres do not screen for this.
How is this different from the false widow?+
Steatoda species (false widows) are superficially similar — similar shape, dark colouration, and comb-footed build — but have no red hourglass and are medically insignificant. Steatoda bites can cause localised pain but are not true latrodectism. Any glossy black spider with a red hourglass is a real black widow; black-but-hourglass-free spiders in BC are almost always Steatoda or other harmless species.
Related species