I tried to pick most of them out, and all 5 batches have been IPAs or American pale ales. Tasted one of the recent batches and now my throat is swollen and I lost my voice. You'd think that once the stingers go through the boil they'd lose their potency. That's what it is? A yellow jacket? Should have known that. My throat hurts after drinking the bee beer.
Yep, it's a yellow jacket. They bite, too, and will come after you for the sweat on your skin in a dry summer. I'm not a fan of them and they can sting repeatedly. They nest in papery nests both above and below ground and should probably be sought out and exterminated if you can find them.
My Wife is highly allergic to wasp venom and has an epi-pen for emergencies in her purse. I'd advise you to take a couple of benadryl and get to an emergency room as a precaution. If your airway swells closed, you'll be in some serious trouble. Don't mess around with wasp stings!
It's unlikely they left any stingers or venom in the beer unless you have an abdomen or whole bug parts in the wort. Unlike bees, they don't have any barbels on their stingers, so they don't lose the stingers when they sting. They can sting you repeatedly as often as they'd like. The workers are highly aggressive and LOOOOOVE sugary sweet liquids, rotting fruit, and meat. Another reason for them to bite is so they can get at some blood. This is a tactic they take with any animals they come across when there's nothing else easy to eat.
Set out some sugary juice of some sort, observe them feeding on it and track them down to their nest from a safe distance. Use a spray insecticide for yellow jackets that sprays a good 20 feet or so and hose down the nest in the early morning hours, when all of them are huddling around the next to conserve heat. Cold wasps aren't nearly as capable as being aggressive and you should be able to kill them all at this time without suffering too many stings. Again, get someone that isn't allergic to them to do the spraying.
As a tip, if you find yourself with a wasp or some other flying bug you don't like in your home and have run out of bug spray, use hairspray. A high hold hairspray (think aqua net) will solidify the little buggers mid-flight.