Stung by an insect

Recently I was up in a tree and being that its summer here there are plenty of wasps around.
One started to hover around my head and body and no matter how much I tried to shew it away he just hung around. Then it must have called to its friends or something because before I knew it there were about five of them hovering around me and they all seemed to be getting a little bit excited so I rappelled down quickly out of the tree and they left me alone.
I thought to myself it must be terrifying to be stung multiple times up in a tree. I'm thinking maybe during the summer I should take up some sort of emergency repellent that I can quickly deploy in case I'm attacked.

Anyone been in a similar or worse situation?
What did you do?