Another poke in the eye.

How do you know if a wasp is angry? You don't know it, you feel it. On the other hand if you are a scientist you can tell a wasp is angry simply by looking at their face. Black spots indicate aggression, although getting close enough to see their face probably means you'll be screaming and covering your eye like it was poked with a hot iron. I figured since only the female stings why haven't the scientists considered looking between their legs? Another useless bit of information brought to you by government sponsored stimulus.

http://www.dailymail.co.uk/sciencetech/article-1304578/How-spot-angry-wasp-Scientists-recommend-looking-face.html