The yellowjacket hover fly, or Virginia flower fly, is a completely harmless mimic of yellowjackets. No more dangerous than a housefly, it buzzes around and seems aggressive. This defensive tactic no doubt leads many people kill it out of fear and ignorance.
As with other true flies, you can distinguish them from the wasps they mimic by their single pair of wings, short antennae, and flylike compound eyes. This and other syrphid flies are famous for visiting flowers, hovering around them and intimidating people who think they might sting.
Learn more about this and other flower flies (syrphids) in their group entry.
In the South, hover flies are called "good news flies" or "good news bees" because they hover right in front of your face, as if to give you some news.
Flower flies do not bite or sting. They play a role in pollination and many help to reduce the numbers of aphids and other insects injurious to crops or garden plants.