Best bait for wasps is raw bacon. No kidding- they love it, and it has a strong enough smell that it is good at attracting them.
Make one of these out of a bottle:
water with a drop of dish soap in the bottom up to about 2-3cms from the inverted neck (I cut them so the neck goes lower down, hang the bacon with some string or put it in a little cup like the pic so it is out of the water. The dish soap breaks the surface tension on the water so that when the bugger buzzes around in there he gets properly wetted and drowns. Even if he manages to climb out of the water the soap will lower the surface tension enough that he will suffocate as it will block the pores through which he breathes.
I've been trying to trap some at work that are flying inside; no bacon there so tried sweet fruit drinks and beer and they don't even come close to it. Bacon is the trick.