Southern black widow vs Brown widow
These two are easy to mix up. Here's how to tell a southern black widow from a brown widow, and whether either one bites or stings.
Southern black widow
Latrodectus mactans
Brown widow
Latrodectus geometricus
≠The key differences
Black widows are usually shiny black with a solid red hourglass on the underside and lack the spiky egg sac; their bites are often considered more medically significant.
⚖︎Side by side
| Southern black widow | Brown widow | |
|---|---|---|
| To humans | Venomous bite | Venomous bite |
| Size | Females 8-13 mm body length; males 3-6 mm body length | Females 7-15 mm body length; males 3-6 mm |
| Colours | Black, Red, Brown, White | Tan, Brown, Orange (hourglass), Cream (egg sac) |
| Family | Theridiidae | Theridiidae |
| Habitat | Sheltered, undisturbed sites near the ground: woodpiles, boxes, garages, basements, crawlspaces, hollow stumps, under eaves and inside cluttered storage. | Sheltered spots on buildings and other man-made structures, garages, sheds, under eaves, inside boxes and among clutter; also vegetation in warm climates. |
| Range | Southeastern and south-central United States, west to Texas and Oklahoma and north to about the Ohio Valley and southern New England; most common in the southeast. Exact range and taxonomy can vary with local populations. | Probably native to Africa; now found in warm regions worldwide, including the Americas, Asia, Australia, the Middle East and many islands. |
| Active | Most active in warm months (spring to fall); nocturnal and most active at night when hunting in their webs. | Year-round in warm climates; most active in spring through autumn; primarily nocturnal but present in webs day and night. |
| Pest? | No | Yes |
🔍How to spot a southern black widow
- Shiny black, globular abdomen on females with a red hourglass marking on the ventral side.
- Females 8-13 mm body length; males much smaller and often brownish with dorsal markings.
- Tangled irregular cobwebs in sheltered, undisturbed areas near the ground or in buildings.
- Hourglass marking is usually on the underside of the abdomen; look at web location and body shape if marking is not visible.
🔍How to spot a brown widow
- Look for a small tan to brown widow with a broken orange or cream hourglass on the underside of the abdomen.
- Check for the distinctive round, spiky or bumpy egg sac (often cream, tan or pinkish).
- Note the mottled geometric dorsal markings and banded or plain brown legs; females are much larger than males.
- Brown widows are usually found in sheltered, man-made structures rather than out in open vegetation.
?Frequently asked questions
What is the difference between a southern black widow and a brown widow?
Black widows are usually shiny black with a solid red hourglass on the underside and lack the spiky egg sac; their bites are often considered more medically significant.
Is a southern black widow or a brown widow more dangerous?
Southern black widow: Venomous bite. Brown widow: Venomous bite. Female bites inject neurotoxic venom (latrotoxin) that can cause local pain, muscle cramps, sweating, nausea, elevated blood pressure, and in severe cases respiratory difficulty. Bites are venomous and can cause local pain, swelling, redness and sometimes muscle cramps, nausea or headache.
Identification from photos is never certain: don't handle insects you can't identify, and get medical advice for bites, stings or allergic reactions.