Late last week I noticed a few harmless yellowjackets on the inside of my office window screen. Today I was stung by one of the insects in the process of leaving my office. Which leads me to evaluate the assumptions in my initial statement, "harmless yellowjackets." Either (a) yellowjackets were/are not harmless, and/or (b) they were not yellowjackets, but hornets or wasps. Sometimes it's hard to determine what assumptions you have made until something proves you painfully wrong. I'd been told since childhood by my family that yellowjackets are harmless, and I've never been afraid of them.
There IS a difference between the three bugs, yellowjackets, hornets, and wasps, not that I understand insects or species classification well enough to know the difference, and Wikipedia is little help as they all have different tables (you'll see my comments requesting that be fixed in their discussion sections w/in a few mintues of this posting), but all three sting. Even so, I am unable to identify the bug now, as it was crippled by my hand crushing it on the doorknob and put out of its misery by the retributive depths of my sole, and there were not enough remains for a thorough autopsy.
The next thing I got to test in this encounter after my assumptions, was my allergies. In my childhood I was allergic to bee stings. Most stings would merely result in massive swelling and occasional puffy eyes. If the stinger remained in my skin, I would start having difficulty breathing until the stinger were removed with tweezers. Since then, I have developed asthma (though mild), but simultaneously my allergies have weakened. Additionally, I have never been stung by a wasp/hornet/yellowjacket. This of course means that I had WAY too many independent variables (asthma, allergies, age, type of bug) of which I was simaltaneously testing the effect on the dependent variable (my ability to breathe), and no good control. I still stand by my reported results (survival, no reaction other than the normal one of PAIN), but I must repeat the experiment in a more controlled environment (allergy tests) to determine causality of survival and estimate future mortality rate.