Question
I live in the north central part of South Carolina. Every spring (May and June) we have these wasps to appear and they work largely in flower beds around the front door. They are a nuisance since they are buzzing around any time anybody is in the area. The flower beds were back filled with sand and these wasps love to dig in them and carry their "food" into the hole. I would like to know abut the life cycle of the wasps and if there is any thing I can do to discourage them invading each year.

Answer
Although female Cicada Killer Wasps rarely sting unless disturbed, homeowners may become alarmed or frightened because of their very large size (nearly two inches) and foraging habits in unwanted areas. These solitary wasps may become a nuisance when they dig holes in lawns, sand base volleyball courts, flower beds, gardens, and golf course sand traps, kicking out a six to eight inch diameter horseshoe-shaped pile of dirt (mound) around the nest entrance. Males have especially aggressive territorial behavior, but have no sting. Females are difficult to provoke, can sting, but rarely do. The female wasps are not aggressive and control is rarely needed except in unwanted places. Adults appear in mid to late summer (July and August) causing special concern to individuals with young children.

Solitary wasps (such as a cicada killer) are very different than the social wasps (hornets, yellowjackets and paper wasps). Cicada killer females use their sting to paralyze their prey (cicadas) rather than to defend their nests. The female wasps are non-aggressive and rarely sting unless touched, caught in clothing, disturbed by lawn equipment, etc. Though males aggressively defend nesting sites, they have no sting. Adults feed on flower nectar and sap exudates.

These wasps are commonly seen in late summer skimming around the lawn, shrubs and trees searching for cicadas. Cicadas are captured, paralyzed by a sting and used for food to rear their young. After stinging a large cicada, the female wasp drags it up a tree, straddles it and takes off toward the burrow, partly gliding. When trees are not available, the cicada (prey) is dragged to the burrow on the ground. Cicadas are very large insects, sometimes called "locusts." They sing loudly (noisily) in trees during late summer. Overwintering occurs as a mature larva within a leathery, brown cocoon in an earthen cell. Pupation occurs in the spring lasting 25 to 30 days. Adult wasps emerge about the first week in July in Ohio. Emergence continues throughout the summer months. Adults live about 60 to 75 days (mid-July to mid-September) while they dig new nesting holes (burrows) in full sun where vegetation is sparse in light, well-drained soils. Eggs are deposited in late July through August. Eggs hatch in one to two days and larvae complete their development in 4 to 14 days. There is only one generation per year.

Burrows & Nests
There may be many individuals flying over a lawn, but each female digs her own burrow six to ten inches deep and one-half inch wide. (They do not nest together.) The soil is dislodged by her mouth and loose particles are kicked back as a dog would dig. The excess soil thrown out of the burrow forms a U-shaped mound at the entrance, causing unsightly mounds of earth on the turf. This ground-burrowing wasp may be found in sandy soils to loose clay in bare or grass covered banks, berms, hills as well as raised sidewalks, driveways and patio slabs. Some may nest in planters, window boxes, flower beds, under shrubs, ground cover, etc. Nests usually are made in the full sun where vegetation is sparse, especially in well-drained soils. Occasionally they establish in golf course sand traps. (A very gravelly or bare area is preferred.)

Cicada Killer Wasps may tunnel as much as six inches deep and another six inches horizontally. At the end of the burrow are usually three to four cells where one to two cicadas are placed in each cell with one egg. If all the cells are filled, secondary tunnels are constructed and provisioned. A single burrow may eventually have 10 to 20 cells

Many insecticides are labeled for wasp control. If control is necessary, locate the nests during the daylight hours. Treat after dark or before dawn when female wasps are in their nests and it is cool, ideally less than 60 deg F. During darkness, use a flashlight covered with red cellophane for lighting. Wear protective clothing. Males roost on plants near burrow sites, and are best controlled by capturing in an insect net during the day.

One can apply bendiocarb (Ficam), carbaryl (Sevin), or diazinon dust onto each nest entrance if the infestation is not too widespread. Do not disturb the burrow as the female must walk through the dust in order to get a challenging dose of the insecticide. If the entire lawn is involved (10 to 20 or more burrows), a spray with the same insecticides may be more practical. Repeat treatments may be needed for two to three weeks if new wasps move into the area. At close range, adults can be killed with a wasp aerosol of synergized pyrethrins or resmethrin as they light on foliage or enter the nest burrow. The professional, licensed pest control operator should be used especially if one is sensitive to possible stings. Other materials labeled for wasp control include acephate (Orthene), allethrin, amorphous silica gel (Drione), chlorpyrifos (Dursban), cyfluthrin (Tempo), cypermethrin (Demon, Cynoff), fenvalerate, permethrin, propoxur and resmethrin. Before using any insecticide, always read the label directions to confirm current listing of pests, and follow safety precautions.