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I use plastic vines up top to provide extra anchor points for webbing. Swimbait is right though, the enclosure is rather large. It's not a huge issue, it's not like you put a 2 inch spider in there, but it is almost certainly contributing to the lack of webbing. Avics just seem to settle in more easily and thus web more in more appropriately sized enclosures. It's obviously up to you if you don't want to move it to something smaller, but you may have to deal with not seeing much webbing. Good luck.