A female garden orb web spider on her web. Note the stitch like Stabilimentum in front of the spider. This structure in the spiders web has been widely debated and many theories have surfaced as a result. It used to be believed that the structure stablilizes the web, more recently a theory that the stablilimentum actualy reflects UV light to attract insects was also investigated. The most widely accepted theory is that the stabilimentum makes the web visible to birds and mammals, thus preventing damage to the web.