why do writing spiders write?

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"I found this pretty spider this morning. We always called them 'writing' spiders. I was wondering what function does it help for them to 'write'?" e-mailed Tamera Partin, my friend with Mast General Store.

Writing spiders, a.k.a. garden spiders, or to spiderologists, Argiope aurantia, are one species that everyone seems to like or at least tolerate because the striking yellow and black arachnids often set up shop in the garden where they eat garden pests. 

The reason for the silk zig-zag "writing," known as a stabilimentum, or web decoration, is debated, but the one theory that makes the most sense to me is that it makes the web visible to birds so they do not fly through it, which would damage the web, forcing the spider spinner to have to re-spin it.

An old folk tale says that if you find your name written in the web, you only have a short time to live. I've checked a lot of spider scribbling in my life, and if your name is WWWWWWWWWWWW, then you better watch your step, avoid lightning, steel rigging, rock climbing, coal mining, fast cars, tsunamis, poorly maintained airplanes and unsinkable ships in the North Atlantic. Just a thought. 

Thanks, Tamera for the photo and query. 

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