SOUTHERN BLACK WIDOW

Scientific name

Latrodectus mactans

Size

The average size of mature, female Southern Black Widow spiders is approximately .5 inch, with a leg span of 1.5 to 2 inches. Mature, male Southern Black Widow spiders are much smaller - approximately 1/3 the size of the female.

Description

Southern Black Widow spiders are a glossy jet-black, with a bright-red hourglass marking on the underside of their abdomen. They generally have a red dot on the very back end of the abdomen, just above the spinnerets as well. The hourglass of the Southern Black Widow is typically complete; with the bottom half (farthest from the head) having more rounded or squared corners, making the hourglass similar to an anvil in appearance.

In addition to the typical hourglass marking on the underside of their abdomen, immature Black Widow spiders can vary greatly in the way they are marked on the top of their back. Typically they have red or white spots running down the middle of their back. Sometimes they will also have red and white markings patterned down the sides of the abdomen.

Distribution

The Southern Black Widow is found throughout the eastern United States, being most common in the southeast states. Outside of the United States, the Southern Black Widow is found in eastern Mexico and the West Indies.

Notes

As with all widow spiders, only the female of the species is considered dangerous. The much smaller male is considered harmless. Southern Black Widow spiders are nocturnal, which means they are active during the nighttime. They spend most of their time hanging "upside down" in their web, which often makes the hourglass marking immediately visible.

Southern Black Widow spiders are typically not aggressive, and bite as a defensive measure when they are attacked or feel threatened. They will often retreat into hiding, but are more protective of their web when there are egg sacs present.

As can be seen in the photo below, the egg sac of the Southern Black Widow is grayish-tan colored, and round.

Southern Black Widow
Photo used by permission:
© 2002 John White

Southern Black Widow
© 2007 David W. George

Note the bright markings on the back of this immature Southern Black Widow.

Immature Southern Black Widow
© 2007 David W. George

Web

The web of the Southern Black Widow does not resemble the typical spider's web, such as the garden spider's web, that is often associated with spiders. It instead resembles a cobweb, constructed of very strong white silk. The web will often be constructed under rocks or logs, or in large cracks and crevices, where it will be dark and the web will be protected from the weather. Webs will sometimes be constructed on lawn furniture, wood piles, sheds, barns, and in garages as well.

For more information on dangerously venomous spiders, please see the Venomous Links page.

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