October, 2016

Southern Black Widow

Perhaps one of the most recognized spiders, the southern black widow (Latrodectus mactans) is both common and often overlooked here in central Texas. No other globular-shaped spider is shiny black with a red hourglass marking on the underside of its abdomen. Widows live in tangled webs with very tough silk strands. The web is usually near a crevice or corner, such as under rocks, so the spider can retreat to a protected place when threatened. Because of this kind of web placement, it is often hard to get a good look at a black widow before it crawls out of sight. The spider is very reluctant to leave its web because its long legs are rather awkward when crawling on the ground.

Female black widows are large for a cobweb weaver (up to 10 mm long), but really not that big compared to many other kinds of spiders. Despite that, they are the most venomous spider in the U.S. Their bite can feel only like a pin prick, but the site soon becomes very painful; the venom contains a neurotoxin that affects muscle contractions. This is one spider whose bite should be treated at a medical facility. It is important to collect the spider so it can be properly identified to determine the correct treatment. The smaller males are not venomous and are much more colorful than their mates.

The individual in the image shown above is a superstar in arachnid circles. Her photo graces the cover of a folding identification guide called "Spiders of Texas."