Spider identification
Most "black widow" photos taken around here are this spider. The false black widow is glossy, dark and round bodied, it sits in the same style of tangled web, and it lives under siding trim, in window wells, garages and basements across Ontario. The difference is the marking, and it is an easy one to check.
Glossy dark brown to purplish black, 4 to 10 mm, with a round, slightly oval abdomen. The northern false widow (Steatoda borealis) has a pale line along the front edge of the abdomen and sometimes a faint pale line down the middle; the triangulate cobweb spider (Steatoda triangulosa) has a zigzag of cream triangles down the back. Neither has a red hourglass on the underside. The web is an irregular tangle, like a common house spider's but usually lower and darker.
Under siding trim and flashing, in window wells, around the foundation, inside garages, sheds, basements, crawl spaces and cupboards. It prefers dark, dry, undisturbed corners near the ground.
Outdoors from spring to fall, indoors all year. Adults can live two or three years, so the same corner can hold the same spider for a long time.
Rare, a sharp local sting that fades within a day. It bites only when pressed against skin. The European reputation of the noble false widow does not apply to the Ontario species. Most "spider bites" in Ontario are never confirmed; see the bite section of our guide to common spiders in Ontario for what a real one looks like.
Removal takes the web, the spider and the egg sacs, and because it lives low on the house the foundation line, window wells and the bottom of the siding get particular attention on every visit. Where a corner under the trim refills we treat that site. Indoors, vacuuming the web and spider is the fix; we quote indoor work separately for existing customers. Every visit ends with a written summary of what we found and where product was applied, if any. Our spider control service and 60 day guarantee pages have the details and pricing.
Common house spider, Northern black widow. The common house spider is browner, mottled rather than glossy, and lives higher on the house. The northern black widow is shiny jet black with red marks on the underside, and in our area is found almost only in the Pinery and dune habitat near Grand Bend. If you can see the underside and there is no red, it is not a widow. The full list with photos is in the common spiders in Ontario guide.
Good to know
Turn it over, or photograph the underside. A black widow has a red hourglass or red marks on the belly and is jet black and shiny. A false widow is dark brown or purplish, has no red, and often has a pale line across the front of the abdomen.
No. A bite is rare and comparable to a wasp sting that fades in a day. There are no lasting effects.
No. Vacuum the web and the spider and check the window wells outside, which is usually where they come from. If you want the outside of the house done, that is our service.
Related guides: Northern black widow in Ontario, Why spider webs keep coming back. Service areas where this spider is found: Grand Bend, Sarnia and Bright's Grove, Goderich.
