Something else we were discussing this afternoon..
You need a few wasp traps. 1 Jam jar, 1 desert spoon of jam (raspberry or strawberry tends to be best), 1 teaspoon washing up liquid. Fill 1/3 with water, shake well, place next to hive.
The wasps fall for it every time, the bees ignore it.
With a jam jar they can easily fly out. What I do is get a plastic milk carton. Put in mixture as Vortex says. I then cut little flaps that I bend up in the sides of the carton towards the top of the carton. The wasps crawl in, take flight and cannot fly out again so usually bump into the sides and fall in the liquid.
The wasps are early this year. I have had to close down all hive entrances much earlier than usual.
The weaker of my two hives has been "bothered" by wasps the past few days - did find one in the crownboard and during insection came across another 3. Found to my horror that I'd left a small gap in the OMF which they were getting in through. Now sealed, entrance lessened and a variety of traps left about.
Seems to have diminished though the odd one does make it through the front and doesnt always immediately get balled out. I'm hoping they are coming from a nest found at my next door neighbours which would be within striking distance