Black Widow vs Brown Widow
Latrodectus mactans vs Latrodectus geometricus
Both are widows and both are medically significant. The brown widow is tan and mottled rather than glossy black, with an orange hourglass instead of a red one, and its spiky egg sac is unmistakable. Do not treat brown as harmless.
The one thing that settles it
The egg sac. A brown widow's egg sac is covered in silk spikes and looks like a tiny sea mine. No other widow makes anything like it, and it is far easier to see and identify than a marking on a spider's belly. If there is a spiky egg sac in the web, the spider is a brown widow.
Side by side
| Character | Black Widow | Brown Widow |
|---|---|---|
| Danger | Dangerous | Dangerous |
| Egg sac | Smooth, round, papery cream sac | Covered in silk spikes — unmistakable, unlike any other widow |
| Colour | Glossy jet black | Tan to dark brown, not glossy — which is exactly why it gets missed |
| Hourglass | Red, on the underside | Orange or yellow, on the underside |
| Legs and abdomen | Slender unbanded legs, plain round abdomen | Banded legs and a mottled, patterned abdomen |
| Bite | Severe muscle pain and cramping spreading from the bite | Medically significant but usually milder, and often staying local |
| Where you meet it | Woodpiles, meter boxes, sheds, crawl spaces, under garden furniture | Plant pot rims, letterboxes, playground equipment, under garden furniture |
Why they get confused
Less that they are confused with each other, and more that the brown widow is not recognised as a widow at all. Everyone has been taught to look for a shiny black spider with a red hourglass, so a tan mottled spider with banded legs gets waved off as a harmless house spider. Across much of the southern US the brown widow is now the one you are more likely to actually meet, and it favours exactly the places people put their hands — pot rims, letterboxes, the underside of garden chairs.
If you still can’t tell
Look for the egg sac before you look at the spider. It is the one character here that is unambiguous, visible without turning anything over, and stays in the web after the spider has hidden. Failing that, treat any round-abdomened spider in a tangled web near ground level as a widow until the underside says otherwise, whatever colour it is.
Common questions
Is a brown widow less dangerous than a black widow?
Its bite is usually milder and more often stays local to the bite, but it is still a widow and still medically significant. Treat it with the same care.
Which one am I more likely to find?
In much of the southern United States, the brown widow. It has spread widely and is still spreading, and in a lot of that range it is now encountered more often than the black widow.
Are the males dangerous?
Effectively no, for either species. Males are much smaller and differently marked. When someone is bitten it is by an adult female.
Full records
- Black Widow Dangerous
- Brown Widow Dangerous
Where this was checked
- iNaturalist — Latrodectus mactans checked 2026-07-30
- iNaturalist — Latrodectus geometricus checked 2026-07-30
- CDC/NIOSH — Venomous Spiders checked 2026-07-30
Last reviewed 2026-07-30. We identify, we don’t diagnose — what we can and can’t tell you.