Issue 13, July 30, 2012
Cicada killer continues to be very numerous in many parts of Illinois this summer. These wasps are about 2 inches long, black with yellow markings, and have reddish, transparent wings. The females dig ½-inch-diameter burrows that extend about seven to twenty inches into the soil. This results in mounds of loose soil around the burrow openings. Annual (dogday) cicadas are captured, stung to paralyze them, and dragged down into the burrows. Eggs laid on the prey hatch into wasp larvae that eat the paralyzed but still living prey. Pupation occurs in the burrow with adults emerging the next summer.
Cicada killer adult.
Male cicada killers establish aerial territories where the females are located. Because bee, wasp, and ant stings are modified egg-laying devices, males cannot sting. However, they are intimidating to people entering their territory, by buzzing and hovering around one's head. They may even butt you with their head as they do this to intimidate other male cicada killers.
Females are very unlikely to sting, with the only stings that I have heard of due to stepping on them barefoot or grabbing them barehanded. Thus, the main concerns are people's reaction to the wasps. Their burrows are also disruptive to sand traps and turf areas. Cicada killers tend to prefer sandy soil and areas with sparse turf or other ground cover for their burrows.
Reduce their numbers in turf areas by using cultural methods to improve turf coverage and density. Mulching bare soil areas should also discourage female burrows. Carbaryl, sold as Sevin Dust, and deltamethrin, sold as DeltaDust, are effective in eliminating females when the dust is sprinkled next to the burrow opening. As with many other species of animals, once the females are gone, the males leave. (Phil Nixon)