Do orb spiders eat their webs?

There was an orb spider in my back yard garden a couple of weeks ago. It kept moving the web every couple of days, but I noticed that there was not a trace of the old webs anywhere. Nothing knocked it down. It just disappeared completely. Do they eat the old webs before they make a new one?|||Yes orb spiders do eat there web before they make a new one because if they dont they just wont have enough energy.