garden spiders

Another member of the Orb-weaver Spiders (Family Araneidae) is the Garden (Black and Yellow Argiope) Spider (Argiope aurantia).  This is not only a common spider, but it is very famous as the Writing Spider of E. B. White’s childhood classic Charlotte’s Web.

Garden Spiders construct their orb webs much closer to the ground than Araneus or Golden Silk Spiders.  They may place their web within a window pane, or certainly among the plants of your garden.  These spiders are active during the day, and do not retreat to a constructed hibernaculum as does Araneus.   When threatened, however, they will crawl off the web or drop to the ground and hide in the vegetation.

Garden Spiders sit in the middle of the web, on the upper surface, with their head pointing down.

Their webs are extremely easy to identify.  An adult will build a web about two feet in diameter, and the web will tilt at an angle.  In the center of the web, the spider constructs a very visible long, thin, zig-zagged zone that scientists call the stabilimentum (juveniles make a circular stabilimentum that is roughly the size of the spider).  It is so named because the first explanation of its purpose was that it helped “stabilize” the web.  Later it was theorized that its purpose was to make the presence of the web very obvious.  As the thinking went, these spider put a lot of energy into constructing their webs, so they don’t want a bird to accidently fly through it and cause damage. 

Later, a wonderful study gave us what we think is the real purpose.  Most insect use different portions of the wave lengths of light than we do.  They see in the ultra-violet area, and when one views flowers in this wave length, one sees a very different image that we humans see.  A bug is flying about looking for a flower to land on, and it is looking for something reflecting ultraviolet light.  It lands and gets a meal of pollen and nectar.  So guess what.  Garden Spiders construct a stabilimentum that reflects ultraviolet light.  Here comes the bug flying along looking for a flower.  It sees the ultraviolet image, flies to it, and gets stuck in the web and attacked by the spider.  How smart is that?

When E. B. White was writing Charlotte’s Web, there was a Garden Spider web just outside the window.  Because of the zig-zagged stabilimentum, the author thought about the spider “writing” on its web.  Therefore, the spider star of the book became known as the “Writing Spider.”