That zig-zag has a name, and the name is wrong. Argiope aurantia, the yellow garden spider, builds a textbook orb web up to 60 cm across, then lays a dense vertical band of bright white silk through the hub and sits on it, head down, all day. Eugene Simon called the structure a stabilimentum in 1895, on the assumption that it braced and stabilised the web. It doesn’t. The band is only loosely attached to the surrounding threads and contributes almost nothing structurally. The name stuck anyway. What makes it interesting is that it is built from different material to the rest of the web. An orb is a composite of at least four silks, each from its own gland: - Frame and radials: major ampullate silk, the dragline, stiff and strong, taking the tension - Capture spiral: flagelliform silk, extensible to several times its resting length so a flying insect is decelerated rather than bounced out - Adhesive: aggregate glue, laid as hygroscopic droplets that pull water from the air to stay ta...