@Shannon
Very nice, thanks for telling me how those guys are called. I thought it is a robber horse fly (just "Bremse" in german), but didn't find anything with that name. So I thought I have a name in my head that doesn't exist. Puh, so I was not completely wrong...very calmative

@Don
Very interesting too, didn't know that they have their own name. But I think I knew what kind of blue ones you mean, we have them here in switzerland too. Down there on Sardinia they had another blue, more dark, or were almost completely black.

And to get an end, here a last picture of the most affected one: