Vampire flies and conference call etiquette

There was an annoying fly in the meeting room today. It loved to buzzzz around my face and to land on my arms even though I was trying to smack it all the time. Pretty hard to do if you are talking on a fixed phone and concentrating on the call.

At one point I feel my arm stings and I see the damn fly sitting on my arm again on top of my sweater. When I move up my sleeve I see 7 big white bumps on glowing red skin. Oh great I was sharing the room with a vampire-type of fly while being stuck in the call! Argh. It must have been a horse-fly.

And then at the end of my meeting with 2 of my regular supplier's contacts when we are wrapping up all of a sudden a third voice comes in "oh hi, this is X, I still had a question".
Geez isn't there some conference call etiquette that requires to introduce yourself at the start of the meeting if you are listening along??? This is the second time that he has done that.