# Black Widow Spider in Ontario — Spider Squad

## Species in Ontario
Northern black widow: Latrodectus variolus

(Note: The southern black widow, Latrodectus mactans, is not established in Ontario but is the more commonly depicted species in media.)

## Is the Black Widow in Ontario?
Yes, but rare. Latrodectus variolus is the species found in Ontario. Confirmed populations exist in several areas of southern Ontario including:
- Point Pelee and Pelee Island
- Niagara Peninsula
- Parts of Essex, Kent, and Lambton counties (southwestern Ontario)

Their range in Ontario is at the northern edge of the species' territory. Populations are sparse compared to US states with warmer climates.

## What They Look Like
The northern black widow has the characteristic shiny black body, but the red marking is different from what most people expect. Rather than the classic solid red hourglass on the underside of the abdomen, Latrodectus variolus typically has two separate red spots or a broken hourglass on the underside, and often has red spots on the dorsal (top) surface of the abdomen as well.

Body: 8 to 13 mm (female). The female is large, glossy black, with the red marking described above. Males are smaller, patterned, and rarely encountered.

## Where They're Found
Black widows prefer: dry, undisturbed, low-to-ground locations. Outbuildings, wood piles, under rocks, in old rodent burrows, in rarely-used equipment sheds, under decks with ground clearance. They do not wander into active living spaces the way house spiders do.

In Ontario, sightings are almost exclusively in rural southern Ontario near the species' range edge. Urban and suburban Ontario has very few confirmed reports.

## Bite Risk
Black widow venom (alpha-latrotoxin) is a potent neurotoxin. Bites cause latrodectism: muscle pain and cramps (especially abdominal), sweating, elevated heart rate, nausea, and headache. Symptoms can be severe and persist for hours to days. Medical attention is warranted for suspected black widow bites, particularly in children, elderly individuals, or anyone with cardiovascular conditions.

That said, bites from Ontario black widows are extremely rare. They bite only when threatened — typically when pressed against skin or disturbed in a retreat. Fatalities in North America from black widow bites are historically very rare.

## What to Do if You Find One
Do not handle it. If you find a confirmed black widow on your property (rare but possible in rural southern Ontario), contact Spider Squad for a targeted treatment. Do not use DIY products — professional-grade bifenthrin applied by a licensed operator is effective.

## Common Misidentification
Many "black widow" reports in Ontario are other species:
- False black widow (Steatoda grossa): dark, rounded abdomen but not glossy black, no red hourglass — not medically significant
- Black cobweb spiders (various): dark but much smaller, different body shape
- Cellar spiders in dim lighting

If you're unsure, the red marking on the underside is the key feature. True black widows in Ontario are rare enough that any claim of one is worth verifying.