Some of you may know this but I didn’t and only just found out in Greece.
Burning coffee grounds, maybe 30g in a saucer outside is a very good wasp deterrent even when there is food around. They really hate the smell. You only need it to smoulder by lighting a little plvut and it lasts a while.
I’ve only tried on fresh grounds but can work on used apparently so a new use for that used espresso puck!