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Species Latrodectus geometricus - Brown Widow

Light Brown Widow - Latrodectus geometricus - female FL brown widow - Latrodectus geometricus Immature Brown Widow - October 20, 2008 - Latrodectus geometricus Brown Widow? - Latrodectus geometricus Brown Widow? - Latrodectus geometricus Creepy - Latrodectus geometricus Brown Widow? - Latrodectus geometricus - female Latrodectus geometricus - female
Kingdom Animalia (Animals)
Phylum Arthropoda (Arthropods)
Subphylum Chelicerata (Chelicerates)
Class Arachnida (Arachnids)
Order Araneae (Spiders)
Infraorder Araneomorphae (True Spiders)
No Taxon (Entelegynae)
Family Theridiidae (Cobweb Spiders)
Genus Latrodectus (Widow Spiders)
Species geometricus (Brown Widow)
Other Common Names
Geometric button spider, Brown button spider, Gray widow spider

(The name "button spider" is not commonly used in the United States, it is more commonly used in other countries, such as South Africa).
lat"ro-dek't[schwa]s gee-o·met'·tr[schwa]·cus
Synonyms and other taxonomic changes
Explanation of Names
Latrodectus geometricus Koch, 1841
Female: about 12-16 mm (> 0.5 inch) long (body length only, not including legs)
Male: much smaller, 6-8 mm (about half the body length of a female) but with longer legs.
The brown widow is highly variable in color. It may be almost white to almost black. Typically, it is a light to medium brown, with an orange-to-yellow hourglass marking on the underside of the abdomen; the coloration of the hourglass often is a good indication of this species. The leg segments are banded, with one half of each segment lighter in color than the other half. The back often has a row of white spots (rarely orange or light blue), and there are a few white stripes on each side. Darker individuals lack these markings and are difficult to distinguish from black widows.



If an eggsac is present, this is the best identifying characteristic. Brown widow eggsacs are tan, spherical, and have many small tufts of silk sticking out from them. They resemble a 'sandspur.' The other widows make white, smooth eggsacs that tend to be pear-shaped.


(Net Ref. 3)
southern US (BG data), World wide in the tropical zone. It was introduced in Florida and has since been observed moving north through Georgia, and into South Carolina; it has also been officially recorded in California, Alabama, Mississippi, and Texas.
Found around buildings in tropical climates.(1) However, it is an introduced species and is the most human-adapted of the species occurring in the South Eastern US. Its webs may occur anywhere there is sufficient space to make one. It may be extremely abundant on houses and other man-made structures (e.g., barns, fences, guard rails, bridges). It reproduces frequently and disperses rapidly, making it nearly impossible to control.
yr round in CA & FL (BG data)
Typically insects, but has been observed killing small toads that have gotten caught in its web (but no confirmed record of eating the toad). (link to images)
Life Cycle
Females can live up to 3 years, while the males only live from 6 months to 1 year. The Brown Widow is the most actively reproducing widow species, producing up to 5000 young per female per season.
Widow Bites:
NOTE: It is recognized that this particular species of widow is most likely not medically significant (not an immediate medical concern to those who are bitten). (Net Ref (4)) The brown widow produces clinical effects similar to that of the black widow but the typical symptoms and signs being milder and tending to be restricted to the bite site and surrounding tissues. (Print Ref 1)

Brown widow spiders usually curl up into a ball, and drop to the ground as a primary defense. It is highly recommended that people leave this spider alone; observe, but don't touch.

The brown widow is an extremely timid spider which has rarely been reported to bite.

For more general information about all types of Widow spiders, please refer to the Latrodectus genus info page.

Be very careful when working around areas where widow spiders may be established. Take proper precautions-wear gloves and pay attention to where you are working. The reaction to a widow bite can be painful, and the victim should go to the doctor immediately for treatment.
Print References
Muller, G.J., Black and Brown Widow Spider Bites in South Africa. A Series of 45 Cases. S-Afr-Med-J, 1993. 83(6): p. 399-405.
Internet References
3) Venomous Spiders in Florida: A detailed article by G. B. Edwards, Taxonomic Entomologist, Florida Dept of Agriculture & Consumer Services
4) Univ. of California, Riverside: Insect Information: A brief fact sheet about the Brown Widow written by R. Vetter, MSc.
Works Cited
1.Spiders and Their Kin: A Golden Guide from St. Martin's Press
Herbert W. Levi, Lorna R. Levi, Nicholas Strekalovsky. 2001. St. Martin's Press.