Joro Spiders Can Extrude Silk for Up to 70 Feet

Q: I’ve noticed spider silk stretching straight across my yard from tree to tree. They look like high tension wires! How do they do that? 

A: You are seeing dragline silk that female Joro spiders have extruded through their spinnerets, located on the abdomen. The spiders build their webs by extruding silk until it catches a breeze, which takes the end to an attachment point. They string bridgeline between other attachment points, gradually building an organized framework from which they can attach the sticky capture silk.

There is a great illustration of this at bit.ly/GAsilk. The threads of silk are incredibly strong and elastic, as you have found when walking in your yard and running into a web. Joros can extrude silk for up to 70 feet, which can obviously make a massive web. Do what many do: Hold a cut branch in front of your face to catch the web before it catches you.