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Southern black widow

Latrodectus mactans
Also called black widow, shoe-button spider

A bite from an adult female can cause strong, spreading muscle pain and cramps, so get medical advice right away if you think you were bitten.

If you think you were bitten or stung, call Poison Help. Free, private, any hour.1-800-222-1222Call 911 for trouble breathing, swelling of the face or throat, or severe symptoms.
Southern black widow, photo 1
Photo: Maura, CC BY 4.0, via iNaturalist
SizeAdult female body about 8–13 mm (about 1/3 to 1/2 inch), roughly 1.5 inches with legs spread; males about 3–6 mm (1/8 to 1/4 inch)
Where in the houseGarage, basement, outside near the house, closets
WhenSeen most in late spring through fall; indoors it can be found year-round in sheltered spots.

Check these features

  1. Adult female is glossy jet black with a round, bulbous abdomen
  2. Red or orange hourglass on the underside of the abdomen, with the two halves joined in the middle
  3. Often a red spot just above the spinnerets on the top of the abdomen
  4. Messy, tangled, very strong web built low to the ground in a dark corner
  5. Round grayish-tan egg sac with a small point on top

Bites and stings

The bite may feel like a pinprick or go unnoticed, with little swelling. Within about 30 minutes to a few hours, pain can spread from the bite with muscle cramps (often a hard, rigid belly), sweating, nausea, headache or raised blood pressure. Symptoms usually ease within a few days. Get medical advice right away for any suspected bite; children, older adults, pregnant people and anyone with heart or breathing problems should be seen promptly.

What to do

  1. Move away from the spider, then wash the bite area with soap and water and put a cool, damp cloth or wrapped ice on it.
  2. Call Poison Help at 1-800-222-1222 (US, free, any hour) for advice on what to do next.
  3. Call 911 for trouble breathing, swelling of the face or throat, or severe symptoms such as spreading pain, chest tightness or strong muscle cramps.
  4. If you can do it safely, take a photo of the spider or trap it in a jar so it can be identified; do not handle it with bare hands.
  5. Do not cut the bite or try to suck out venom.

Look-alikes

Northern black widowIts belly hourglass is split into two separate red marks, and it usually has a row of red spots down the back.
Western black widowVery similar but lives in the western states; range is the easiest clue.
False black widow (Steatoda grossa)Brown to purplish-black with no red hourglass underneath, and much milder bite.
Brown widowTan to brown with an orange hourglass and a spiky, burr-like egg sac.

Why it came inside

It mostly lives outdoors in woodpiles, sheds and clutter, but sometimes moves into garages, crawl spaces and basements that are dark and rarely disturbed.

Keep it out

  • Wear gloves when moving firewood, boxes, stored items or yard debris.
  • Shake out shoes, gloves and clothing left in garages or sheds before putting them on.
  • Keep firewood and lumber stacked away from the house and clear clutter from garages and crawl spaces.
  • Seal gaps around doors, windows, pipes and vents and fit door sweeps.
  • Vacuum webs and egg sacs, then seal and discard the vacuum bag outdoors.

What helps

Links go to Amazon search results so you can compare current options. As an Amazon Associate I earn from qualifying purchases. Always follow the product label.

Sticky traps

Flat glue traps set along walls and in corners show what is moving through and where. Place them where pets and children can't reach.

See options on Amazon
Door sweep

Closes the gap under an exterior door. If you can see daylight under the door, bugs can get in.

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Caulk and sealant

Silicone or siliconized acrylic caulk closes cracks around windows, pipes and baseboards. Bigger gaps need foam backer rod or expanding foam first.

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Weatherstripping

Seals the gaps around doors and windows that let in drafts and bugs alike.

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Vacuum with a hose

Lets you remove bugs, webs and egg sacs without touching them. Empty the bag or canister outside right away.

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Bug catcher

A long-handled catcher moves a spider or insect outside without you having to touch it.

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UV flashlight

Scorpions glow under ultraviolet light, which makes them much easier to spot at night.

See options on Amazon

Sources

  1. CDC / NIOSH
  2. University of Florida IFAS Extension
  3. Penn State Extension
  4. Clemson Cooperative Extension (HGIC)
  5. Connecticut Agricultural Experiment Station
  6. University of Arkansas Arthropod Museum
  7. LSU AgCenter

Checked October 18, 2026. Rating backed by 4 sources. How we rate danger.