Issue 13, August 8, 2016
We are receiving calls about cicada killers and sand wasps. These are solitary wasps, the female of which digs a 6- to 10-inch burrow (with a diameter of 1/4 to 1/2 inch) in the ground. She locates and stings a large insect such as a cicada or katydid, drags it to a chamber in the burrow, and lays an egg on it. The female covers up the burrow, digs another one, and repeats the process.
The egg hatches into a legless, grub-like larva that eats the paralyzed insect, pupates, and emerges the next summer as an adult. Research has shown that this stung, paralyzed host "wakes up" weeks later if taken from the female before she lays her egg on it. Of course, in nature, the host is eaten before it has a chance to wake up.
Male wasps establish aerial territories and patrol for intruders. Someone walking into the territory typically is confronted with a large wasp hovering in front of the face, zipping to the side and to the back before leaving.
A male cicada killer drives off males entering his territory and tries to mate with female cicada killers that enter. Apparently, after determining an intruder is neither, he ignores the person. Unfortunately, in walking across a lawn, fairway, or other area where these wasps are nesting, the process is repeated as a person walks through each male's territory.
These wasps are unlikely to sting. Wasp and bee stingers are modified egg-laying devices, so males are not equipped to sting. Females sting if crushed, as when stepped on or grabbed by bare hands. As a boy, I spent hours trying to stomp cicada killers coming to their nest or run them over with my bicycle tire and was never stung--I always wore shoes.
Cicada killers are about 2 inches long and black, with yellow band-like marks. The head and transparent wings are brownish red. There are several common species of sand wasp, which tend to be black, with yellow, white, or orange banding. Sand wasps are typically 1 to 1-1/2 inches long, with black transparent wings.
Cicada killer on post.
Though these wasps are not dangerous, they are intimidating. In home lawns, educating the human residents may foster tolerance. Wasps are more common in bare soil areas, so sodding, planting ground-covers, or mulching may greatly reduce the problem.
Nesting areas in public areas can become a major problem. Individual burrows in dry areas can be treated by applying carbaryl (Sevin Dust) or deltamethrin (DeltaDust) alongside burrows where the female wasp will track through it. She will be killed after ingesting the dust while grooming.
If sand boxes, volleyball courts, and other infested areas can be covered with a tarp during many of the daylight hours, the cicada killers will leave without the need for insecticide use. When the females are killed or leave, the similar-appearing males will leave. Sand used below children's swings, jungle gyms, and other playground equipment can be replaced with bark mulch or shredded tires. (Phil Nixon)