The one in the first photo, looks like a black wasp - but I could be wrong.
I'm not sure that they were sweat bees, that was a while back and can't remember exactly what they looked like, but no the Apple trees died almost instantly, very odd.I am learning from the tiny bit of looking on the web about these sweat bees that there are many variations of these.
I didn't know that they would eat leaves. Did your apple trees survive the leaf eating? I have 2 that I planted this year. It's my first time trying to grow apple trees.