Both the brown widow and the black widow belong to the same infamous genus—Latrodectus—known for its potent venom and dramatic appearance. However, despite their shared lineage, these spiders are quite different in terms of color, behavior, danger level, and where they’re found. While one carries a deadly reputation, the other is more mild-mannered and less harmful.
Let’s compare the brown widow vs black widow and help you understand exactly how to tell them apart—and how concerned you should be if you find one.
Brown Widow vs Black Widow
| Feature | Brown Widow (Latrodectus geometricus) | Black Widow (Latrodectus mactans / spp.) |
| Color | Light brown to tan or grayish | Glossy black |
| Markings | Orange or yellow hourglass | Red hourglass on underside |
| Abdomen Shape | Rounded with geometric spots or stripes | Smooth, shiny, more uniform |
| Web Placement | Open areas (eaves, fences, furniture) | Dark, secluded areas (woodpiles, sheds) |
| Aggression Level | Shy, less likely to bite | More defensive, may bite if disturbed |
| Venom Potency | Less toxic | More toxic (medically significant) |
| Common Regions | Worldwide (tropical/subtropical) | Mostly U.S. and North America |
| Egg Sacs | Spiky, round, tan | Smooth, white or tan |
| Danger to Humans | Low risk | Potentially serious for vulnerable people |
Color and Markings
The most obvious difference between the two is color.
The black widow has a glossy black body with a distinct red hourglass on the underside of her abdomen. The rest of her body is smooth and shiny, with little to no other pattern.
The brown widow, however, is light brown to grayish with orange or yellowish hourglass markings, and often has striped legs and geometric blotches on the top of her abdomen. These patterns help camouflage her better in outdoor structures like fences or patio furniture.
Web Location and Appearance
Both spiders build messy, irregular cobwebs made from strong silk. However, their preferred web locations differ.
- Brown widows prefer exposed but sheltered spaces such as:
- Eaves
- Mailboxes
- Outdoor plastic furniture
- Window wells
- Eaves
- Black widows prefer dark, hidden places such as:
- Under rocks or logs
- Sheds
- Basements
- Crawl spaces
- Under rocks or logs
If you see a widow-type web in a visible and airy place, it’s likely a brown widow. If the web is in a dark, tucked-away corner, black widow is more likely.
Venom and Bite Danger
Both spiders have neurotoxic venom, but they differ in strength and effect.
Black Widow Bite
- The black widow’s bite is more potent, causing latrodectism, a condition marked by:
- Severe muscle pain
- Cramping
- Nausea
- Sweating
- High blood pressure
- Severe muscle pain
- While rarely fatal, the bite can be dangerous to children, the elderly, or immunocompromised individuals.
Brown Widow Bite
- The brown widow also has neurotoxic venom, but it’s less potent and typically results in:
- Localized pain
- Mild muscle stiffness
- Redness or itching
- Localized pain
- Serious symptoms are extremely rare, and brown widow bites are generally not considered medically significant.
Behavior and Aggression
Black widows are more defensive, especially females guarding their egg sacs. They may bite if they feel threatened or cornered, particularly when disturbed inside a shoe, glove, or woodpile.
Brown widows are more timid and less likely to bite. They tend to retreat if approached and only bite when severely provoked.
Egg Sac Differences
A surprising way to tell these spiders apart is by looking at their egg sacs.
- Brown widow egg sacs are tan and spiky or bumpy, resembling a sea urchin or sand burr. They’re often found near the web.
- Black widow egg sacs are smooth, round, and pale, usually tucked into hidden spots within the web.
If you find a sac with spikes, you’re likely dealing with a brown widow infestation.
Distribution and Spread
The black widow is native to North America and has multiple regional species:
- Latrodectus mactans (Southern U.S.)
- Latrodectus hesperus (Western U.S.)
- Latrodectus variolus (Northeastern U.S.)
The brown widow is invasive and originally from Africa, but now found in:
- Florida and Gulf States
- Southern California
- Hawaii
- Worldwide in tropical/subtropical regions
Interestingly, in areas where brown widows have spread, black widow populations seem to decline, possibly because brown widows outcompete them for habitat.
FAQs
1. Are brown widow spiders more common now than black widows?
In many urban and suburban areas, yes. Brown widows have spread rapidly in the southern U.S. and often take over places where black widows once lived.
2. Are brown widow bites medically serious?
Very rarely. While they do contain venom, their bites are milder than black widows and generally don’t require medical attention unless symptoms worsen unexpectedly.
3. Do both spiders have the hourglass marking?
Yes, but the color differs:
- Black widow: Red hourglass
- Brown widow: Orange or yellow hourglass
4. Should I kill a brown widow if I find one?
Not necessarily. They’re not aggressive and rarely bite. If you’re concerned, you can remove them safely using gloves and relocate or treat the area without panic.
5. Which spider poses more danger to pets?
Black widows are potentially dangerous to small pets if bitten. Brown widows are less toxic and typically do not bite animals unless heavily provoked.
