The trap's not a problem. We've used the good ol' cut a plastic bottle in half and invert the top into the bottom so it makes a funnel. This is fine, only the wasps won't go in: they don't seem to like Coke or honey water or vegemite. The flies, on the other hand, think all are great! Hnnnnh! I'm trying some fermenting grapes this morning. More on that later.
LOL! True biological control! I like that. We've got a native paper wasp nest up under the eaves of the house and that's not a real problem. We've also got a solitary wasp nest (mud) on the back window and even
*that's* not a problem (the homemaker is huge: nearly 6cm long!) It's just these annoying European creatures that seem to want to phlock over my garden and dare anyone to get close...Quite rightly, too! When I was four, I emptied my kiddy teapot over a paper wasps' nest (WHY did I do that???? Was it an exaggerated case of my wanting to share?) The wasps streamed forth and, basically, shot down the front of my pinafore dress, stinging me all over my front! Owwwwwie! I can still remember the fire of it! Dad reckoned that was why I grew up to have a more-than-satisfactory bust measurement.
When I was doing entomology, I had a huge solitary wasp in my insect collection (ie. mounted, labelled and pinned in a collection box). Long after the animal had been dead, I managed to brush the tip of its abdomen with my hand and *it stung me* with long-crystallised venom left in its stinger. Boy, that hurt!
Both these encounters have served to make me extremely wary of wasps and their allies!