Black Widow Spiders (Latrodectus)

Along with the recluse spider and hobo spider, Latrodectus species are considered spiders of medical importance in the United States.

Using the language of spider talk, Latrodectus belong to the larger cobweb spider family, Theridiidae. Five Latrodectus species live in North America:

• Latrodectus bishopi: Red Widow
• Latrodectus geometricus: Brown Widow
• Latrodectus hesperus: Western Black Widow
• Latrodectus mactans: Southern Black Widow
• Latrodectus variolus: Northern Black Widow

The bite of females contains a neurotoxin that can cause severe health problems, and at the extreme end, death.

Symptoms appear about an hour after the initial bite and can include nausea, shortness of breath and chest or abdominal pains. Anyone suspected of being bitten should immediately seek medical attention.

Latrodectus species typically live in and around residential areas, predominantly in the southern half of the United States, although the range of both the Northern and Western species extends into Canada.

With legs extended, widow spiders can measure up to an inch and one-half in length. Any corner of a wood pile, basement or porch provides sufficient space for the female to build a tangled looking, untidy web.

The traditional description of female widows begins and ends with their dark black bodies and red hour glass marking on the underside of the abdomen.

While the description rings true for the most common Western, Southern and Northern species, the appearance of both the Red Widow and Brown widow spiders (Latrodectus geometricus), break the rule.

A non-native species introduced from Africa, the female Brown widow body (pictured below) comes in a variety of brown shades, with dark spots and orange patterns on the abdomen. The underside of the abdomen also shows the red hourglass markings. (Thanks to DK in FL for sending the Brown widow picture)

Brown widows often get ranked as the least aggressive of the Latrodectus species, and while their venom is toxic, they typically do not inject large amounts into their victims. Therefore, health personnel consider them less dangerous than the Black widow species.

The Red widow, the rarest of the Latrodectus species, has a range limited to Florida. The female has a red to orange cephalothorax and legs. The dark abdomen shows orange to red spots on the top.

Fear of Black widow spiders often leads to misidentification. For example, a genus of Theridiidae spiders, Steatoda, often go by the nickname, false black widows.

© 2008-2010. Patricia A. Michaels