Thursday, August 09, 2007

Patient Spider

This morning, the view out of the office window at the Audubon Center at Francis Beidler Forest was slightly obscured by the overnight arrival of a Black-and-yellow Argiope (Argiope aurantia).

Except for the characteristic "writing" in the middle of the web, the deadly silk is nearly invisible. The zig-zag webbing is called a stabilimenta, because it was originally believe to aid in stabilizing the web. There are several hypotheses regarding the purpose of the stabilimenta, but the strongest appears to be that the highly visible threads prevent birds from flying through and destroying the web. Also, only diurnal (in the day) spiders add the stabilimenta to their webs.

This Black-and-yellow Argiope is quite patient. During a day of observation on her web just beyond the computer screen, she has moved exacty twice. Once to pounce on and quickly devour a tiny flying insect and once to pounce on, wrap up, and slowly drain a medium-sized fly. The rest of the day has been spent as seen in the image. Patiently waiting for the next meal to fly through what likely appears to be an opening in the forest though, the web and clean glass would demonstrate otherwise.

She needs to be careful. There are plently of tube-building Mud Daubers in the area and they can easily take the spider as food for young when they hatch. If fact, one JUST attacked but found itself on the wrong side of the web. The argiope is located between the web and the window. Her location on the web appears to have been a life-saving decision!

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