Spiders in Ontario
Ontario is the only province in eastern Canada with a resident widow spider, and it is not the one the internet usually names. The northern black widow clings to a handful of sand barrens and dune systems along Lake Erie; everywhere else in the province the spiders are orb weavers, jumping spiders, fishing spiders and cellar cobweb spiders, none of which can harm a person.
On this page
- What spiders live in Ontario?
- Which Ontario spiders are actually dangerous?
- Where you meet them
- Spider season in Ontario
- Mistaken identities
- Common Spiders in Ontario
- Biggest Spiders in Ontario
- Deadliest Spiders in Ontario
- Most Venomous Spiders in Ontario
- Less Venomous Spiders in Ontario
- Living with Ontario's spiders
- Frequently asked questions
What spiders live in Ontario?
Ontario spans more latitude than any province east of Manitoba, from the Carolinian forest of the Lake Erie shore — walnut, sassafras, tulip tree — north across the Canadian Shield to the muskeg and open tundra of the Hudson Bay lowlands. Several hundred spider species are recorded across that range, and where you stand changes the list entirely.
Twenty-six of the conspicuous ones are profiled below. The province's southern tip is warm enough to hold animals that get no further north in Canada, which is the whole reason Ontario has a resident widow spider at all. Away from that narrow band the fauna is the familiar northern mix: sheet-web weavers and small wolf spiders underfoot in enormous numbers, orb weavers on porches from August, jumping spiders on sunlit walls, and cobweb spiders in every basement.
Which Ontario spiders are actually dangerous?
One, and the older version of this page named the wrong species. It listed the western black widow as Ontario's deadliest spider, but Latrodectus hesperus belongs to western North America and is not established east of the prairies. Ontario's widow is the northern black widow, Latrodectus variolus, which reaches its northern limit in the sand barrens, dunes and prairie remnants of the extreme south: the Lake Erie shoreline, Point Pelee, Long Point, the Pinery and the Ojibway Prairie near Windsor. It is uncommon even there, living in low, undisturbed, sun-warmed cavities: rodent burrows, hollow logs, stone piles, stacked boards. The mature female is glossy black with a row of red marks along the top of the abdomen and a red hourglass beneath, often split in two. Her bite can cause severe muscle cramping, sweating, abdominal pain and raised blood pressure and should be assessed in hospital, though deaths are extremely unlikely with modern care.
Three other species on the original list do not deserve their billing. The eastern parson spider was called one of the province's deadliest; it is a fast nocturnal ground hunter whose bite stings and may itch for a day, nothing more. The hobo spider was listed as highly venomous, but the necrotic wounds once blamed on it were never reproduced experimentally, and the US Centers for Disease Control dropped it from its list of spiders of concern in 2017; it is a Pacific Northwest species, scarce in Ontario. The yellow sac spider and the northern yellow sac spider do bite people more often than most spiders, because they hunt at night and get trapped in bedding, but the result is a brief sting and a red mark; the old claims of tissue destruction are not supported.
There are no recluse spiders in Ontario. Loxosceles is not established anywhere in Canada, so a brown recluse bite diagnosed in Toronto, Ottawa or London is almost always something else.
Bitten by a suspected widow? Wash the bite, apply a cold pack, keep the limb still and go to an emergency department, especially for a child or older adult, or if pain spreads to the abdomen, chest or back. Do not cut, suck or heat the wound. Photograph the spider if it is safe, because identification changes treatment.
Where you meet them
Houses, garages and sheds
Cobweb spiders own the ceiling corners of almost every Ontario home, and the small mottled one behind the furniture is usually a triangulate cobweb spider. Barn funnel weavers take window wells and cellar stairs with a flat sheet and funnel retreat, while the woodlouse spider — cream abdomen, dark red body, huge forward-pointing fangs — lives under damp boards and flowerpots hunting sowbugs.
Gardens, fields and hedgerows
From mid-August the orb weavers take over. The yellow garden spider hangs a large web with a heavy zigzag ribbon in tall vegetation, the marbled orb weaver hides in a curled leaf beside a wheel-shaped web in damp woodland edges, and the barn spider builds on porch rails, barn beams and dock posts, taking the web down again at dawn. The bold jumping spider, black with a bright abdominal triangle and iridescent green jaws, hunts by sight on fence rails and deck boards all summer.
Lakes, rivers and cottage country
Ontario's largest spiders live near water. The dark fishing spider is the biggest by leg span and is regularly found on cottage walls and tree trunks well back from the shore. The six-spotted fishing spider — a nursery web spider, despite being grouped with the orb weavers on the original page — sits at the waterline of marshes and slow streams, reading the surface film with its front legs and diving when disturbed.
Spider season in Ontario
Spider season runs from late spring to the first hard frost, but the peak is narrower. Most species hatch small and feed all summer, so adults and full-sized webs appear from mid-August through early October — which is also when mature males wander in search of females and turn up on living-room walls.
The cold is survived rather than escaped. Eggs, spiderlings and part-grown juveniles overwinter in leaf litter, under bark and inside plant stems, insulated by snow and protected by antifreeze compounds in their tissues; the mechanics are covered in our guide to where spiders go in the winter. Basement cobweb spiders simply carry on breeding through January.
Mistaken identities
The most consequential confusion in Ontario involves widows. False widows of the genus Steatoda are dark, glossy and round-bodied, hang in the same kind of tangled web and are common right across the province — but they have no red hourglass, showing at most a pale band across the front of the abdomen, and they are harmless.
The second is funnel weaver against funnel weaver: barn funnel weavers, grass spiders and hobo spiders build the same sheet-and-funnel web, and no photograph separates them. The third is not a spider at all — harvestmen, with one fused body section, no silk and no venom glands, are reported as giant spiders every autumn.
Common Spiders in Ontario
- Black-footed Yellow Sac Spider
- Common House Spider
Biggest Spiders in Ontario
- Dark Fishing Spider
- Striped Fishing Spider
Deadliest Spiders in Ontario
Most Venomous Spiders in Ontario
Comb-footed Spiders
Sac Spiders
Sac SpidersBlack-Footed Yellow Sac (Cheiracanthium inclusum)Identify the black-footed yellow sac spider (Cheiracanthium inclusum): size, colour, its silk retreat, where it lives, and what its bite rea
CheiracanthiidaeNorthern Yellow Sac Spider (Cheiracanthium mildei)Identify the northern yellow sac spider (Cheiracanthium mildei): size, pale colour, its silk sac, how it spread across North America, and whFunnel Weaver Spiders
Ground Spiders
Less Venomous Spiders in Ontario
Orb-weaver Spiders
Orb WeaversStarbellied Orb-weaver (Acanthepeira stellata)Identify the starbellied orb-weaver (Acanthepeira stellata): the spiked star-shaped abdomen, size, its grassland orb web, range and whether 
Orb WeaversBarn (Araneus cavaticus)Identify the barn spider (Araneus cavaticus): size, markings, the orb web it rebuilds every night, where it lives and whether its bite is da
Orb WeaversMarbled Orb-weaver (Araneus marmoreus)Identify the marbled orb weaver (Araneus marmoreus): marbled abdomen, the orange pumpkin spider form, size, web and retreat, range, and whet
Orb WeaversShamrock Orb Weaver (Araneus trifolium)Identify the shamrock orb weaver (Araneus trifolium): size, the white-dotted globe abdomen, banded legs, its web and retreat, range, season 
Nursery Web SpidersSix-spotted Fishing (Dolomedes triton)Identify the six-spotted fishing spider (Dolomedes triton): size, stripes, how it walks on water, its range, and whether its bite is dangero
Orb WeaversBanded Garden (Argiope trifasciata)Identify the banded garden spider (Argiope trifasciata): silver banding, size, the zigzag in its web, egg sac, range, and whether its bite i
Orb WeaversGray Cross Spider (Larinioides sclopetarius)Identify the gray cross spider or bridge spider (Larinioides sclopetarius): size, silver-edged pattern, its lamp-lit webs on steel bridges, 
Orb WeaversCross Orb Weaver (Araneus diadematus)Identify the cross orb weaver (Araneus diadematus) by the white cross on its abdomen: size, colour, web, egg sac, range and whether the bite
Orb WeaversYellow Garden (Argiope aurantia)Identify the yellow garden spider (Argiope aurantia): black and yellow markings, size, the zigzag stabilimentum, egg sacs, range and whetherHacklemesh Weaver Spiders
Crab Spiders
Nursery Web Spiders
Nursery Web SpidersStriped Fishing (Dolomedes scriptus)Identify the striped fishing spider (Dolomedes scriptus): size, pale side stripes, stream-bank habitat, how it hunts on water and whether it
Nursery Web SpidersDark Fishing (Dolomedes tenebrosus)Identify the dark fishing spider (Dolomedes tenebrosus): size, chevron markings, where it lives in North America, and whether its bite is daFunnel Weaver Spiders
Jumping Spider
Jumping SpidersBold Jumping (Phidippus audax)Identify the bold jumping spider (Phidippus audax): size, the white triangle, green jaws, how it hunts without a web, and whether its bite i
Jumping SpidersTan Jumping (Platycryptus undatus)Identify the tan jumping spider (Platycryptus undatus): flattened body, wavy abdominal pattern, size, where it lives and whether its bite is
Jumping SpidersZebra (Salticus scenicus)Identify the zebra spider (Salticus scenicus): the black and white bars, the male's oversized jaws, how it hunts without a web, and whether Comb-footed Spiders
Cobweb SpidersCommon House (Parasteatoda tepidariorum)Identify the common house spider (Parasteatoda tepidariorum): size, mottled brown pattern, pear-shaped egg sacs, tangled web, and why its bi
Cobweb SpidersRabbit Hutch Spider (Steatoda bipunctata)Identify the rabbit hutch spider (Steatoda bipunctata): glossy brown body, pale stripe, tangle web in sheds and hutches, and why its bite is
Cobweb SpidersTriangulate Cobweb (Steatoda triangulosa)Identify the triangulate cobweb spider (Steatoda triangulosa): the purple zigzag pattern, yellow legs, its tangle web, and whether the bite Woodlouse Hunter Spiders
Living with Ontario's spiders
Practical precautions are short, and only the first one is about the widow:
- In the southern sand barrens, wear gloves when lifting boards, rocks or stored lumber, and never reach blindly into burrows or debris piles.
- Shake out bedding, towels and clothing left on the floor if sac spiders are active — that is where most Ontario bites come from.
- Seal gaps around basement windows and garage doors in August, before wandering males move in.
- Vacuum webs and egg sacs instead of spraying; removing the web and the insects that feed it works far better than insecticide.
- Leave porch orb weavers alone until frost takes them; each removes hundreds of mosquitoes from your doorway.
For the neighbouring fauna, see Quebec, which shares most of Ontario's forest species but has no widow at all.
Frequently asked questions
What is the most dangerous spider in Ontario?
The northern black widow, Latrodectus variolus. It is confined to sand barrens, dunes and prairie remnants in the extreme south of the province and is uncommon even there. Its bite can cause severe cramping, sweating and abdominal pain and warrants hospital assessment, though it is very rarely life-threatening with modern treatment.
Are there western black widows in Ontario?
No. The western black widow is a spider of western North America and is not established east of the prairies. Older Ontario spider lists, including the earlier version of this page, named it by mistake. The widow that genuinely lives in Ontario is the northern black widow of the far south.
Where in Ontario do black widows live?
Almost entirely in the Carolinian south along Lake Erie: Point Pelee, Long Point, the Pinery, the Ojibway Prairie near Windsor and similar open sand barrens and dune systems. They choose undisturbed, sun-warmed cavities close to the ground, such as rodent burrows, hollow logs, rock piles and stacked boards.
Are there brown recluse spiders in Ontario?
No. Recluse spiders are not established anywhere in Canada. Wounds diagnosed as recluse bites in Ontario are almost always bacterial skin infections, including staph, or another medical condition entirely. Any sore that spreads, weeps or fails to heal should be examined by a doctor rather than blamed on a spider.
Is the hobo spider dangerous in Ontario?
Current evidence says no. Attempts to reproduce the necrotic wounds once attributed to hobo spiders failed, and the US Centers for Disease Control removed the species from its list of spiders of concern in 2017. The hobo is also mainly a Pacific Northwest spider and is scarce in Ontario.
Do yellow sac spiders bite people in Ontario?
More often than most spiders do, because they hunt at night and get pressed against skin in bedding or clothing. The bite stings sharply and leaves a red mark that fades over a couple of days. Older claims that sac spider venom destroys tissue are not supported by the evidence.
Is the eastern parson spider dangerous?
No. It is a fast nocturnal ground hunter that runs rather than fights. A bite is uncommon and produces a short sting, local redness and sometimes itching for a day. Some older regional lists ranked it among Ontario's deadliest spiders, which overstates it considerably.
What is the biggest spider in Ontario?
The dark fishing spider, with a leg span of roughly seven centimetres. It is often found far from water, on cottage walls, tree trunks and woodpiles, which is why it startles people so reliably. The six-spotted fishing spider is similar in size and stays near marshes and slow streams.
When are spiders most active in Ontario?
Mid-August through early October is the peak. Spiders that hatched in spring reach full size then, so webs appear everywhere and mature males wander in search of mates, which is when large spiders show up indoors. Activity ends with the first hard frosts; eggs and juveniles overwinter under litter and bark.
What spiders get inside Ontario houses?
Cobweb spiders dominate: the common house spider and the small triangulate cobweb spider live in ceiling corners, basements and behind furniture year-round. Barn funnel weavers occupy window wells and cellar stairs, and cellar spiders hang in garages. None of them is harmful, and all of them eat other household insects.
Published April 26, 2022 · Last updated September 14, 2026