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How to identify it
- Adult females are shiny black with a round abdomen about the size of a large pea and a red marking on the underside, often shaped like an hourglass.[2][5][1]
- The red marking varies: a full hourglass, two separate triangles, a triangle and a bar, or occasionally almost none. The northern black widow usually has two red spots or a broken hourglass instead.[2][5]
- Males and young look nothing like adult females: they are smaller, with tan, white and red markings, and spiderlings darken with each molt. Males have much longer legs for their size.[2][5]
- Webs are irregular, tough, sticky, messy-looking cobwebs built near the ground in sheltered spots; the female hangs upside down in them.[2][3][5]
- Southern black widow egg sacs are round, tan to grayish, with a single small point.[5]
Look-alikes
| Look-alike | How to tell them apart |
|---|---|
| False black widow (Steatoda) | Chocolate brown and never has red markings.[2] |
| Brown widow | Gray, tan or dark brown with a brown, white and black pattern on top, an orange hourglass underneath, and egg sacs covered in small points.[5][2] |
| Northern black widow | Very similar, but usually has two red spots or a broken hourglass underneath and may have red and white marks on top of the abdomen.[5] |
| Western black widow | The black widow species of the western U.S.; it looks and behaves much the same.[2][3] |
Where it lives
Found throughout North America, most commonly in the southern and western states. They live in undisturbed spots such as woodpiles, eaves, fences, debris, rock walls and outbuildings, and are seldom found inside living spaces.[1][2][4]
Biology and life cycle
Widow spiders come out at dusk and wait in the web for prey, usually close to the ground, retreating to a crevice when disturbed.[2]
Females can store sperm and produce many egg sacs from one mating; UC reports that western black widows lay about 300 eggs per sac and more than 10 sacs without mating again.[2]
Black widows belong to the cobweb spider family, which uses comb-like bristles on the hind legs to wrap prey.[4][3]
Adults can be found year-round in South Carolina. Clemson and UC report that the non-native brown widow is displacing black widows in some places, and Clemson notes that brown widows can kill them.[5][2]
Damage and signs
Health risk
The venom is a neurotoxin: pain starts at the bite and spreads to the chest, abdomen or whole body. MedlinePlus lists severe abdominal or chest pain, muscle cramps and rigidity, sweating, nausea and vomiting among the symptoms and advises getting medical help right away; antivenom is given in some cases but can cause serious allergic reactions. Most cases reported to U.S. poison centers are minor: of 15,299 exposures from 2012 to 2022, about 10 percent needed hospital admission and antivenom was used in 3.4 percent. A Lancet review notes concerns about how well spider antivenoms work.[1][6][8][7]
Control
Prevention
Wear gloves when moving woodpiles, boxes, garage clutter or utility box lids; store shoes and clothing indoors and keep stored gear in sealed bags or taped boxes off the floor.[2][1][5]
Keep them out
Seal cracks in the foundation and gaps around windows and doors, keep screens in good repair, and point outdoor lights away from doors and windows so they attract fewer insects.[3][2][5]
Sanitation
Remove clutter, empty containers and woodpiles near the house, and vacuum up spiders, webs and egg sacs; seal the vacuum bag in plastic and put it in an outdoor trash bin.[3][2][5]
Traps and physical control
Because widows are nocturnal, checking with a flashlight at night and removing spiders and webs directly is an effective nonchemical approach.[2]
Pesticides
UC says insecticides don't give long-term control and treated areas get re-infested; Clemson says to use a product labeled for spiders only if widows remain after habitat cleanup.[3][2][5]
Where black widows live and hide
Black widows live throughout North America but are most common in the southern and western United States.[1]
They settle in undisturbed spots such as woodpiles, eaves, fences and debris piles, and even in outdoor toilets where flies are plentiful. Clemson adds empty flowerpots, utility and irrigation boxes, crawl spaces, basements, sheds and barns.[1][5]
Living areas of homes usually don't have enough insects to feed them, so they nest outside and in garages instead.[2]
If a black widow bites you
Stay calm, wash the bite with soap and water, and apply a cold, damp cloth or ice wrapped in a cloth to reduce swelling; MedlinePlus says 10 minutes on and 10 minutes off. Don't try to remove venom.[1][6]
Remove rings and tight jewelry and loosen clothing. Call Poison Help at 1-800-222-1222 for guidance and get medical help right away.[6]
If it's safe, identify the spider or bring it in a secure container to help with treatment.[1][6]
Keep tetanus boosters current, every 10 years, because spider bites can become infected with tetanus spores.[1]
Avoiding bites
Spiders usually aren't aggressive; most bites happen when a spider is trapped or touched, including when someone touches its web.[1][5]
Shake out clothing, shoes, towels and gear before use, and wear long sleeves, gloves and boots when moving stacked or undisturbed materials.[1]
Where sources disagree
Size: UC gives about 1/2 inch of body length for a mature female western black widow; Clemson says female black widows can reach 1 1/2 inches in total length.[2][5]
How common bites are: UC's widow spider guide calls bites quite rare even where the spiders are common, while UC's general spider guide calls black widow bites fairly common in California. U.S. poison centers logged 15,299 widow spider exposures from 2012 to 2022.[2][3][8]
Raising the limb: NIOSH says to elevate the bite area if possible; MedlinePlus says to keep the bitten area still, with a splint if needed, to slow the venom's spread.[1][6]
Common questions
- What does a black widow bite feel like?
- Often like a pinprick at first, and some people don't feel it. MedlinePlus says a dull muscle pain spreads from the bite within 15 minutes to an hour; get medical care promptly.[6]
- Do black widows live inside houses?
- Rarely in living spaces; they usually nest outdoors and in garages, crawl spaces, basements and sheds where insects are plentiful.[2][5]
- Are black widows aggressive?
- No. They are timid, and most bites happen when a spider is trapped, touched or crushed, or its web is disturbed.[1][5]
- What should I do if a black widow bites me?
- Wash the bite, apply a cold compress, remove tight jewelry, call Poison Help at 1-800-222-1222 and get medical attention; don't try to remove venom.[1][6]
- Where are black widows most common?
- Throughout North America, but most common in the southern and western United States.[1]
- Can a black widow bite kill you?
- Death in a healthy person is very rare, though young children, very ill people and older people are at greater risk. A review of U.S. poison center cases from 2000 to 2008 found most were minor and recorded no deaths.[6][9]
Sources
- CDC / NIOSH, “Venomous Spiders at Work (updated September 28, 2026).” www.cdc.gov/niosh/outdoor-workers/about/venomous-spiders.html (accessed 2026-11-11)
- University of California Statewide IPM Program, “Pest Notes: Widow Spiders and Their Relatives, Publication 74149 (revised March 2017).” ipm.ucanr.edu/legacy_assets/PDF/PESTNOTES/pnblackwidow.pdf (accessed 2026-11-11)
- University of California Statewide IPM Program, “Pest Notes: Spiders, Publication 7442.” ipm.ucanr.edu/legacy_assets/PDF/PESTNOTES/pnspiders.pdf (accessed 2026-11-11)
- University of Kentucky Entomology, “ENTFACT-622: Common Spiders Found Around Homes and Buildings.” entomology.mgcafe.uky.edu/ef622 (accessed 2026-11-11)
- Clemson Cooperative Extension, Home & Garden Information Center, “Widow Spiders in South Carolina (HGIC).” hgic.clemson.edu/factsheet/widow-spiders/ (accessed 2026-11-11)
- MedlinePlus, U.S. National Library of Medicine, “Black widow spider (Medical Encyclopedia).” medlineplus.gov/ency/article/002858.htm (accessed 2026-11-11)
- The Lancet, via PubMed, “Isbister and Fan (2011), Spider bite.” pubmed.ncbi.nlm.nih.gov/21762981/ (accessed 2026-11-11)
- Wilderness & Environmental Medicine, via PubMed, “Kerns et al. (2025), Black widow spider exposures: a retrospective review of the National Poison Data System 2012-2022.” pubmed.ncbi.nlm.nih.gov/39670790/ (accessed 2026-11-11)
- Annals of Pharmacotherapy, via PubMed, “Monte et al. (2011), A US perspective of symptomatic Latrodectus spp. envenomation and treatment: a National Poison Data System review.” pubmed.ncbi.nlm.nih.gov/22116992/ (accessed 2026-11-11)
- iNaturalist, “Latrodectus mactans taxon page (order and family).” www.inaturalist.org/taxa/47381 (accessed 2026-11-11)