Gorgeous Garden Spider

This is the beautiful Black and Yellow Garden Spider, or Argiope spider, Argiope aurantia, which I was excited to notice amid the native plantings while we were visiting the International Crane Foundation in Baraboo, Wisconsin, on Saturday. The female's body can be 1.5" in length and the total size including legs can be up to 3" in diameter. It is a very large, dramatic, gorgeous spider! I have seen one only once before, in my garden several years ago.

I wasn't sure if the white zigzag that looks rather like dental floss was associated with the spider and its web, though it certainly seemed to be. This website has a lot of information about the Argiope spider, and (citing Behavioral Ecology magazine) explains the purpose of the zigzag material, known as stabilimenta:

Stabilimenta are conspicuous lines or spirals of silk, included by many diurnal spiders at the center of their otherwise cryptic webs. It has been shown spider webs using stabilimenta catch, on average, 34% fewer insects than those without. However, webs with the easily-visible markings are damaged far less frequently by birds flying through the web. It is an evolutionary tradeoff the spider can influence every time it builds a new web. The inclusion of stabilimenta is influenced by many factors, including prey density and web location.

I thought that was fascinating. You can see more of the web in the photo below, from which the one above was cropped.