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Black Widow Spiders

Safety Site

Monica Palmer, Safety Administrator

Recreational Safety takes Responsibility and Control

                                            Black Widow Spider

The black widow belongs to a group of spiders commonly known as cobweb spiders. The characteristic red hourglass is located on the underside of the abdomen. Female black widows are dangerous and can bite and inject toxic venom.


The female black widow is normally shiny black, with a red hourglass marking on the underside of the abdomen.

  • The abdominal marking may range in color from yellowish orange to red and its shape may range from an hourglass to a dot.
  • The body of an adult black widow female is about 1/2 inch long.
  • Newly hatched black widows do not have a red hourglass, but develop a white spot.  They can be easily identified by the shape of their spindly legs.


The black widow is commonly found in the following places:

  • Outdoors - woodpiles, rubble piles, under stones, in hollow stumps, and in rodent burrows, privies, sheds and garages.
  • Indoors - undisturbed, cluttered areas in basements and crawl spaces.


  • The bite of the black widow may be painful or it may go unnoticed.
  • The skin may display one or two bite marks with local swelling. Pain usually progresses from the bite site and eventually to the abdomen and back.
  • Severe cramping or rigidity may occur in the abdominal muscles.
  • Symptoms may include nausea, profuse perspiration, tremors, labored breathing, restlessness, increased blood pressure and fever.
  • The pain from the bite will usually persist for the first 8-12 hours.
  • Symptoms may continue for several days.


  • Wear a long-sleeved shirt, hat, gloves, and boots when handling boxes, firewood, lumber, and rocks, etc.
  • Inspect and shake out clothing and shoes before getting dressed.
  • Use insect repellants, such as DEET or Picaridin, on clothing and footwear.


  • Clean the bite area with soap and water.
  • Apply ice to the bite area to slow absorption of the venom.
  • Elevate and immobilize the extremity.
  • Capture the spider, if at all possible, for identification purposes.
  • Seek medical attention if the pain is severe or you have other symptoms. You may need narcotic pain relief or muscle relaxants
  • If you have a heart condition or other heart problem, you may need hospitalization.

Courtesy of U.S. Department of Labor

The decision to seek emergency care should be made early. If the person who was bitten by a black widow spider has more than minor pain or has whole-body symptoms, seek care at the nearest hospital's emergency department. If symptoms are severe, call 911 for emergency medical transport so that evaluation and treatment can start enroute to the hospital.