First, you have to realize that the fear is, overall, irrational. It's as logical as seeing a police officer at a doughnut shop and becoming afraid that he's going to arrest you (even though you have done nothing to deserve it).
Second, you have to be aware of all five of your senses. seeing a bee or wasp does not equal feeling a bee/wasp sting. There is no need to be afraid when you see a bee/wasp, because it doesn't mean you are going to get stung.
Third, just try to take your fear one step at a time. 1. Look at the bee. 2. slowly get close to the bee. Just don't do anything to arouse the bee/wasp, like trying to smack it.