Every summer, since I built it (2011) I've noticed that wasps seem attracted to it. In particular the upright pillars. Which appear to be some sort of treated wood.
It's not harbouring a wasps nest, and they aren't going past it to anywhere else. They are definitely inspecting it, or finding something of interest there.
I did briefly wonder if spiders webs have some sort of attracting smells, as there are a few strands of older webs there at times.
It's not an issue as such (until we get stung). But odd. And happens every year.
Speaking of wasps, is it just me, or are they smaller this year ?