Summary: Cicada killer wasps are not as dangerous as their name sounds. Unless you're a cicada, that is. Cicada Killers are generally not interested in humans.
Cicada Killers are big, and when insects are big they can be scary. The female Cicada Killer does have a stinger, but it rarely attacks people. Cicada Killers are solitary wasps that don't build elaborate hives or have castes of workers like honey bees. They hunt cicadas so that they can lay eggs on them, which will provide food for Cicada Killer larvae. They hunt cicadas using a long, venomous stinger which totally paralyzes the cicada. The female Cicada Killer flies back to her burrow carrying the cicada with her legs, which is fairly remarkable since the paralyzed cicada weighs twice as much as the Cicada Killer.
Cicada Killer wasps hunt cicadas that appear annually, not typically the kind that appear every thirteen or seventeen years. The life cycle of a Cicada Killer is synchronized to match the life cycle of annual cicadas. The adult Cicada Killer does not eat cicadas, but actually eats flower nectar or plant sap.
The egg of a Cicada Killer takes a day or two to hatch and larvae spend most of the year underground feeding on a storehouse of cicada corpses. Male Cicada Killer larvae are left with one cicada while female Cicada Killers are left with two, three, or occasionally even four cicadas to feed on. For this reason the female Cicada Killers are much larger than the males and in circumstances when a female Cicada Killer only receives one cicada to eat as a larva, the female will be much smaller and closer in size to a male Cicada Killer.
Female Cicada Killers kill about 100 cicadas during their life and produce about sixty or seventy new Cicada Killers. Cicada Killer larvae spend the fall and winter underground feeding on cicadas, growing larger, until they are ready to emerge as adult Cicada Killers in the late spring or early summer. Adult Cicada Killers do not survive the winter.
Male Cicada Killers do not have stingers and do not hunt cicadas. Their primary goal in life is to mate with female cicadas. Much of a male's life is spent outside of a female Cicada Killer's burrow fighting with other male Cicada Killers for the right to mate with a female Cicada Killer. The larger the male, the more likely it will be successful. The males often fight with each other in mid-air, forming balls of battling Cicada Killers that have no control over their flight direction. This might be frightening to someone who encounters this behavior in the wild, but Cicada Killers will flee from humans when they are swatted at.
Cicada Killers are sometimes called sand hornets, although they are wasps, not hornets. They probably got the name because they build their burrows in dry, sandy soil. The female Cicada Killer wasps have specialized hind legs that are equipped with spines that can push dirt out of the burrow.
Cicada Killers are distributed across the US. If there is a Cicada Killer burrow that is in an obtrusive area you can clog the entrance to the burrow with a stick and the Cicada Killer will continue to bring cicada bodies to it for a while, and then give up to try a different location. Hopefully the new location will be somewhere out of the way.
Treat cicada killer burrows with Tempo 1% dust to gain some control.