Go to Bunnings and get a couple of the plastic fly/wasp catchers. They work really well. You just unscrew the lid, add some attractant and some water, then pop the lid back on and hang it up somewhere (preferably out of sight!) They only need refilling every few weeks. Just make sure to get the wasp attractant - it's different to the stuff for flies. - Kermit
I got a couple of these traps. Hung up one with the attractant in it on the deck area and didn't catch a single wasp in a week. So just before eating dinner we put sugar and jam and a bit of hot water in the other one to see if that worked as an experiment. It was amazing that just a minute or two after we all came out with some food, the wasps came but instead of going to us and the food on the table, they started going into the trap with the attractant in it rather than flying around us.
Now after a few days the trap with the attractant has heaps of wasps in it (and a cockroach?). And the mixture we made was a fail - no wasps interested in that. We've had dinner outside every night this past week and have barely been bothered by them at all. Great result - well worth it. - MartyH
In the UK we put a jam jar with water in it and a blob of jam on top and place it away from where we were having a BBQ. Wasps are then drawn to the jam and inevitably fall in the water - looks like this: https://www.youtube.com/watch?v=7B2sKeqlPwQ
So the proof is in the pudding. Looks like the wasp traps from Bunnings are working. I think a few flies got in there too. However this seemed to be the solution that had the best outcome. Doesn't smell too great though... - kaylah_rose