What Do Yellow Jackets (Wasps) Do For Work?

Yellow Jackets are a fascinating bunch. I've seen one chase, catch, sting, and carry off a fly in mid flight. My best guess is they are just like sharks. Their only purpose is to eat, fly, and make babies. Their sting for me is enough to give me cold symptoms for a few weeks. Odd reaction, the nurse at the place I drive to says to monitor those stings, for hypersensitive reactions. I touched the nest hidden under a hand rail and the little beggars zeroed in on the hand that touched the nest and stung it. Pheromones I guess? Don't get too close, O.K.???