We have received calls on hordes of large wasps flying around. These are mainly cicada killers, Sphecius speciosus, actually considered beneficial insects because they control cicada. This wasp gets its common name due to the fact that it hunts and provisions each cell within its nest with a cicada, which becomes a food source for the young cicada killer. Cicada killers are an urban nuisance pest, especially when nesting, sometimes in large numbers, in a bare area or area around a structure. People get concerned because the cicada killers resemble giant yellowjackets.
Cicada killers are about 2 inches long and black to red, with yellow banded markings on the abdomen. The head and transparent wings are reddish brown. They are not dangerous, but they are intimidating. Cicada killers are solitary wasps, with the female digging a 6- to 10-inch burrow (1/2 inch in diameter) in the ground. A pile of soil typically surrounds the entrance. The female locates and stings a large insect such as a cicada or katydid and then brings it back to the burrow. She places the insect into a chamber and lays an egg on it; sometimes she puts two in a burrow but lays an egg on only one. She then covers the burrow, digs another, and repeats the process. The egg hatches into a grublike, legless larva that consumes the paralyzed insect. Full-grown larvae overwinter in the burrow, pupate in the spring, and emerge as an adult during the summer, usually in July and August.
Male cicada killers establish aerial territories and patrol for intruders. A male cicada killer drives off other males that enter his territory and attempt to mate with females. Anyone else walking into the territory is typically confronted by a very large wasp, which hovers in front of the face and zips to the side and back. However, after determining that the “intruder” is not a rival, the wasp ignores the individual.
Cicada killers are unlikely to sting a person. Wasp and bee stingers are modified egg-laying devices (ovipositors), so males are not able to sting. Females may sting if crushed, either by being stepped on with bare feet or grabbed with bare hands.
Cicada killers are more common in areas with bare soil, so mulching, planting ground covers, or sodding can reduce associated problems. They become a major problem when nesting in areas accessible to or frequented by the public. Applying permethrin or another labeled insecticide (such as the carbamate-based insecticide carbaryl, Sevin) to the burrowed area should kill females in golf course sand traps. Once females are gone, males leave. In home yards, sandboxes can be covered with a tarp when not in use, as this deters the wasps (and also keep cats out). Sand below swings, jungle gyms, or other playground equipment can be replaced with bark mulch.
Managing cicada killers in volleyball courts and baseball infields is more of a challenge because people with little clothing and much exposed skin are diving and sliding onto the ground. This makes it difficult to recommend using an insecticide on a volleyball court. In these cases, the use of weed or other barriers beneath the sand may be an option. Additionally, raking the sand may create enough of a disturbance to cause the wasps to leave.