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Brown Widow Spider,
Gray Widow, Geometric Button Spider

Latrodectus geometricus

Brown Widow Spider: Overview | Brown Widow Spider Bites | Prevention
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Brown Widow Spider Ventral View Showing Hourglass

Underside of brown widow spider, showing hourglass marking.
Wikimedia Commons, Mfield, Matthew Field,
http://www.photography.mattfield.com, Sept 2009, Los Angeles,CA

Range

Brown widow spiders occur in the southeastern, southern and southwestern United States, as well as worldwide in the tropical zone. The brown widow originally entered the U.S. in Florida and spread its range in the 1990s. They have been encountered and documented in California, South Carolina, Mississippi, Alabama, Texas and Georgia.

Description & Habitat

Brown widow spiders are hard to identify due to the broad range of their coloration and their close resemblance to young black widow spiders. The easiest way to identify a brown widow is by the presence of their unique egg sacs that are woven with silk spikes on the surface.

The color of the brown widow spider ranges from tan to gray and dark brown. There is an orange or yellow hourglass shape on the underside of the abdomen of the females. Males do not have this marking.

The color pattern on top of the abdomen may have some white spots with parallel rows of black spots or a broken red line. This pattern is the source of the name geometric spider. These markings may darken and become obscured with the age of the spider, making it an unreliable source for identification. The spider has eight legs and a round abdomen, and females are 1 to 1.5" in length with the males approximately half that size.

The distinctive egg sacs of the brown widow spider have a spiky, globular form. They look like round white or light brown spheres with spikes protruding all over.


Distinctive egg sac of brown widow spider

Distinctive egg sac of brown widow spider, showing spiky, globular form. Some egg sacs are whiter than shown here.
Wikimedia Commons, Karmalie,
Sept 2008, St. Kitts

Brown widows are most commonly found on the underside of outdoor furniture, in pots, on garbage cans, in garages, or outdoor sheds and in surrounding landscaping.
Brown widows feed on small insects that they capture in their webs. Their eyesight is poor and they rely on the vibrations from their web to alert them of newly captured prey or incoming predators.

A brown widow spider spins a sticky and irregular web that has a tangled or messy design in order to catch prey. Bugs and small insects fly or crawl into the web and get stuck. The web vibrates when a bug has landed on it and the brown widow rushes to the insect and bites it. The brown widow wraps the bug in silk and saves it to feed on after it is done hunting.

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Brown Widow Spider: Overview | Brown Widow Spider Bites | Prevention
Health and Medical Disclaimer

See also: Black Widow Spider, Brown Recluse Spider

Health and Medical Disclaimer

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Information provided at and by DesertUSA is NOT A SUBSTITUTE FOR PROFESSIONAL MEDICAL CARE. If you have a medical concern, or suspect you have a health problem you should consult your primary doctor or specialist.

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