I never knew these critters existed, until I had a few decide to make a home under my driveway a few years ago. This year, I see they are back at the foot of my mail box. We can't get the mail without these insect "drones" buzzing us to check us out and warn us away from their home. My next door neighbor has several nests near her drive too.
I thought it would be good to Muse about Cicada Killer Wasps so that if you should ever run across one, you will at least know what it is. They are ground dwelling wasps that make their appearance sometime in July and hang around through August. Their food of choice? Cicadas, those mysterious insects you hear emitting loud and long buzzing noises during the dog days of summer. Cicada Killers dig tunnels and chambers underground to raise their babies. The females do all the work! When done with their tunnels, they fly off to find cicada victims to bring back to their brood chambers. It's rather gruesome, as the cicada is only paralyzed when deposited in the chambers. A nicely packaged live meal for the hatching grubs to eat. The males spend their time looking for females to "make whoopie", and looking tough and fighting other wasps over "territory". Unlike the females, males have no stingers. They are rather passive-aggressive, preferring to buzz you vs. sting you, but that doesn't mean they won't sting if you aggravate them. It's best to leave Cicada Killers alone, unless they have nested in a location that is inconvenient to your daily living and prevents you from doing what you need to do.
http://www.theatlantic.com/national/archive/2013/07/the-cicada-killers-are-coming/277688/
http://www2.ca.uky.edu/entomology/entfacts/ef004.asp