The wasp nest in the bush can't really even be seen because it's hidden within the mass of leaves. But they sense vibrations such as trimming branches even on an adjacent bush. They whizz out and start looking for the offending party (me).
ell that happened to me a couple of summers back. I was cutting out a dead bush from our front garden and did not know that perfectly camouflaged in the dense dry brown branches was a dry brown wasp nest. The scene played out like a really bad movie. I saw the wasps suddenly seem to float out of it in slow motion. I could make out the detail in each wasp - their legs and abdomens just hanging grotesquely as they turned towards me. I ran in absolute terror! And my partner who was gardening nearby just watched as one wasp caught up to me, went right for my neck, landed on me, and stung. It was horrible. I grabbed my neck and shouted, "I'm hit! I'm hit! I'm hit!" I know it sounds stupid but that's all I could scream. Then I fell and rolled down the grass hill, holding my neck. It was a beautiful sunny day - the neighbors were out, too, and stopped to watch this one-man crazy show they probably didn't understand, and my partner just rolled his eyes at all the drama.I
really don't want to repeat that. I still have a little bump on the side of my neck to remind me of that awful day. But I'm a firm believer in karma. So if I CAN relocate the nest I'd almost pay to do it, but being so inaccessible, I may have to resort to Ken's suggestion, albeit not so ... well ... enthusiastically as him, I guess.