[doph]

Very much this. After multiple very painful stings, I have a zero tolerance policy for nests on the house, but I am very grateful when they show up in the garden. Wasps are more effective at controlling garden pests than any chemical means I've tried. Plus they seem to be the only pollinators of my passionfruit.

[kragen]

Around here the passion flowers are mostly pollinated by a species of bumblebee with an almost-all-black abdomen and beautiful violet wings. So far they haven't stung me, although I'm sure they could, and it would be very painful. I haven't tried capturing them.

[chihuahua]

It sounds like it could be Xylocopa violacea, the violet carpenter bee, found in Europe and Asia: https://en.wikipedia.org/wiki/Xylocopa_violacea