Excellent Lin. My guess would be that the wasp has a nest somewhere nearby in the foliage there & is "guarding" the nest. You might want to be careful when messing around in that area.
Our hummers will chase off birds or butterflies it considers encroaching on it's nectar source.
I am a strong believer in the simple fact is that what matters in this life is how we treat others. I think that's what living is all about. Not what I've done in my life but how I've treated others. ~~ Sharon Brown