LYCOS RETRIEVER 
Black Widow: Underside
built 178 days ago
The female Black Widow is shiny black, usually with a reddish hourglass shape on the underside of her spherical abdomen. Her body is about .5 inches long, 1.5 inches when the legs are spread. Adult males are harmless to humans, about half the female's size, with smaller bodies, and longer legs and usually have yellow and red bands and spots over the back as do the immature stages.
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The adult male black widow is one-half to two-thirds the length of the female, has a small abdomen, and is seldom noticed. The male black widow does possess venom, but its fangs are too small to break human skin. The top side of its abdomen is olive greenish gray with a pattern of cream-colored areas and one light-colored band going lengthwise down the middle. The hourglass mark on the underside of the abdomen typically is yellow or yellow-orange and broad-waisted. The legs are banded with alternating light and dark areas.
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Male widows may be either completely black or maintain some of the immature coloration. They do not possess the hourglass type marking of the larger females. However, males usually have some red marking located on the top or underside of the abdomen.
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This is the not quite as famous first cousin of the Black Widow, known as the Brown Widow, Latrodectus geometricus. BugGuide notes: "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.
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Black widows can be found throughout Arkansas. The body of the female is usually shiny and black and can be up to 1½” long, including the legs. The abdomen appears fat and nearly spherical and it may bear few or many reddish spots. The most characteristic spot occurs on the underside of the abdomen, and it is usually somewhat hourglass-shaped. Males are much smaller and narrower than females, and they have white lines on the abdomen in addition to red markings. Classification and identification of black widows is notoriously difficult. There is so much variation and overlap in characters that it is not always possible to name a given specimen with certainty. It is now understood that at least 2 species occur in Arkansas. The southern black widow, Latrodectus mactans, is probably the most common species in this state. The posterior portion of the red hourglass on the underside of the female’s abdomen may appear more like a rounded rectangle than a triangle, and there is usually a row of red spots on top of the abdomen. The northern black widow, L. variolus, is more common in the northern states. The anterior and posterior portions of the ventral hourglass are not joined at the middle, and red and white marking on top of abdomen tend to be more prominent than in the southern black widow (Kaston 1970)
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