Huge black and yellow wasps in parks, golf courses and back yards are receiving a lot of publicity right now. These are actually Cicada Killer wasps, and although they are intimidating, they very seldom sting. Cicada killer wasps should be considered beneficial because they kill potentially plant-damaging cicadas, but they are also nuisance pests themselves if they occur around people. The size of the wasp is intimidating enough but add to that the males annoying habit of 'dive-bombing ' anything that comes into their territory - including humans. The result is that they get peoples attention quickly.
In most cases the wasps should just be left alone as they likely will not sting and because of their beneficial cicada predatory behavior. In those cases where they cannot be ignored, using Carbaryl (Sevin) as a dust applied to the burrow entrance has been shown to offer excellent control.
Here are a few more article on hornets: