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All about the Black Widow Spider or Widow Spider – their habitat, sting, treatment, and how to avoid a Black Widow Spider bite.

Black widow spider spinning its web

About the Black Widow Spider

Black Widow spider
Latrodectus species

The prevalence of a behavior called sexual cannibalism, where the female eats the male after mating, has led to the common name “widow spiders”. This behavior might increase the chance of survival for the offspring. However, only a few species of females demonstrate this behavior, and most of the documented evidence for sexual cannibalism has been observed in laboratory cages where males could not escape. To avoid being eaten, male black widow spiders typically check if the female has already eaten by sensing chemicals in the web before selecting their mates.

How to Identify a Black Widow Spider

Black widow spider spinning its web

Black Widow Spiders are dark, usually black, medium-sized spiders with light red or orange markings (typically in the shape of an hourglass) on the female’s abdomen (underneath the spider’s body).  Black Widow Spiders (or Widow Spiders) have dark, glossy, globular bodies about 1/2 inch long.  Not all Widow Spiders have the characteristic red hourglass on their stomachs.  Some have two red dots, some have red stripes or dashes, and some have no colored markings at all.

Widow spiders construct webs of irregular tangled silken fibers.  Black Widows often hang upside down in their webs, waiting for prey.  They have poor eyesight and rely on vibrations for detecting prey.

To identify a Black Widow Spider, consider the following:

Color: Black widow spiders are shiny black with a distinctive red hourglass shape on their abdomen. The red hourglass shape is usually found on the underside of the spider.

Size: Adult female black widow spiders are typically about 1.5 inches long, including leg span. Males are smaller and have longer legs. The body of the female black widow spider is about half an inch long and is usually larger than the male.

Web: Black widow spiders build tangled webs in dark, sheltered areas such as garages, basements, and woodpiles. Their webs are usually irregular in shape, and their silk is stronger than steel of the same thickness.

Behavior: Black widow spiders are reclusive and will only bite if they feel threatened. They are not aggressive and will usually retreat if disturbed.

Where to find Black Widow Spiders

Black Widow Spiders can be found under logs, rocks, dark corners or crevices, and debris.  They often prefer shaded places like garages, sheds, or woodpiles.  They prefer to build their nests close to the ground. Black Widow spiders are nocturnal and hunt at night. There are varied species of black widow spiders worldwide – a black widow in the United States and parts of Mexico, red widow in the Middle East, and brown widow in Australia.

Symptoms of a Black Widow Spider bite

Black Widow spiders have particularly large venom glands containing latrotoxin, making a bite from a black widow spider very dangerous to humans (although death from the bite is rare).  Black widows produce a protein venom that affects the victim’s nervous system.

The first symptom, which typically occurs 20 minutes to one hour after the bite, is acute pain at the site of the bite.  Next, the victim may experience muscle cramps, pain, nausea, vomiting, dizziness, fainting, chest pain, and difficulty breathing.  In some instances, the victim may experience abdominal pain similar to that of a gallbladder attack. Symptoms from a black widow spider bite can last for 3-7 days.

The symptoms of a black widow spider bite may include:

  • Pain at the bite site
  • Redness and swelling
  • Muscle cramps and spasms that start near the bite and then spread throughout the body
  • Sweating, chills, and fever
  • Nausea and vomiting
  • Difficulty breathing

Deaths from a Black Widow Spider bite are rare, but if the spider bites a body part with extremely good vascular supply, such as the penis, it can result in the venom being distributed throughout the body before body defenses can be mobilized. For this reason, it is believed that adult fatalities usually occur in males in areas that use sit-down outdoor toilets.

How to treat a Black Widow Spider bite

Juvenile Southern Black widow spider (Latrodectus mactans)

An antivenin is available for Black Widow Spider bites.  If the victim experiences whole-body symptoms, then seek emergency medical treatment.  Otherwise, wash the affected area with soap and water. Apply cold and hot compresses to the bite area or have the victim take a hot bath.  Over-the-counter pain medicine may be used to alleviate the pain. Seek medical attention immediately if you experience any of the following symptoms: severe pain, muscle cramps, nausea, vomiting, difficulty breathing, or a rapid heart rate. If possible, try to capture the spider and bring it with you to the hospital for identification purposes.

NOTE: Female Black Widow Spiders are the poisonous gender. Male Black Widows can bite too, but their bite is not considered dangerous. 

Note that Black Widow Spiders can vary in appearance.

Do black widow spiders provide any benefit to mankind?

Black widow spiders are not necessarily good for anything specific, but they do play an important role in the ecosystem. As predators, they help to control the population of insects and other arthropods. This can be especially beneficial in agricultural settings, where pests can cause significant damage to crops.

Black Widow Spider picture identification guide

  • Black widow spider spinning its web
  • Juvenile Southern Black widow spider (Latrodectus mactans)
  • Black widow spider spinning its web
  • Georgia black widow spider closeup of red hourglass marking
  • Black widow spider (Latrodectus mactans)
  • Black widow spider underside showing orange red hourglass marking
  • Mature female Latrodectus southern Black Widow spider
  • Black widow spider Latrodectus Hesperus male dorsal side
  • Black widow spider Latrodectus Hesperus male ventral view
  • Black widow spider Latrodectus hesperus, male, ventral view
  • Female black widow spider Eruope Latrodectus tredecimguttatus species

Image Credits

In-Article Image Credits

Black widow spider spinning its web via Flickr by Steve Ryan with usage type - Creative Commons License. June 2008
Black widow spider (Latrodectus mactans) via Wikimedia Commons by Ben Swihart with usage type - Creative Commons License. October 2, 2006
Black widow spider underside showing orange red hourglass marking via INaturalist by Ken-ichi Ueda with usage type - Creative Commons License. April 26, 2008
Juvenile Southern Black widow spider (Latrodectus mactans) via Wikimedia Commons by Kazvorpal with usage type - Creative Commons License. August 5, 2017
Georgia black widow spider closeup of red hourglass marking via Wikimedia Commons by Alexdi with usage type - Creative Commons License. December 30, 2011
Mature female Latrodectus southern Black Widow spider via Wikimedia Commons with usage type - GNU Free. 2012
Female black widow spider Eruope Latrodectus tredecimguttatus species via Wikimedia Commons with usage type - Public Domain. September 18, 2005
Black widow spider Latrodectus Hesperus male dorsal side via Wikimedia Commons by Davefoc with usage type - GNU Free. 11/7/2008
Black widow spider Latrodectus Hesperus male ventral view via Wikimedia Commons with usage type - Creative Commons License. October 30, 2008
Black widow spider Latrodectus hesperus, male, ventral view via Wikimedia Commons with usage type - Creative Commons License. October 25, 2008

Featured Image Credit

Black widow spider spinning its web via Flickr by Steve Ryan with usage type - Creative Commons License. June 2008

 

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