“Stabilimentum” Weaver

Argiope aurantia – the Yellow Garden Spider

Despite being the “common” garden spider in this part of the world Argiope aurantia is not necessarily the commonest spider in our gardens … but when it does appear, what a beauty.

This one of the orb web spider, which is to say the group of spiders that spin a traditional spiders web … which not all spiders do by a long chalk. This species can produce webs of up to two feet diameter. The specimen we have here was having a packed lunch as you can see from the side view picture. Yellow garden spiders breed twice a year. Females usually stay close to where they hatched while the males wander in search of a female, building a small web near or actually in the female’s web, then court the females by plucking strands on her web. Often, when the male approaches the female, he has a safety drop line ready, in case she attacks him. The male uses the palpal bulbs on his pedipalps to transfer sperm to the female. After inserting the second palpal bulb, the male dies, and is sometimes then eaten by the female

The shiny, white zipper that is part of the web and runs from top to bottom is called a stabilimentum – it’s purpose is not entirely clear. It was once thought to provide stability to the web, hence its name, but nowadays it is thought to be an attractant for possible prey species as it reflects bright UV light that they are drawn to. It also seems to attract male spiders to the female’s web.