'The Hitchhiker's Guide To The Galaxy" has the words "don't panic" inscribed in large friendly letters on its cover. Words to live by when unexpectedly confronted by the presence of a cicada killer wasp. It is far and away the largest wasp in North America (the western tarantula hawk is longer, but slimmer) and it is harmless -- at least, harmless for us. To cicadas, it is their worst nightmare.
Cicada killers are not social wasps like yellow jackets or hornets. They live a solitary life. Males pop out of their burrows from mid-July through August (they're early this year for some reason) and hang around drinking nectar with the guys waiting for the girls to show up a week or two later. Soon after mating, the females start to dig burrows in the ground, getting them ready as nurseries for their hungry grubs.
Once she's completed her nests, she goes looking for some nice, fat, juicy cicadas. It's not difficult. The cicadas themselves make their presence rather obvious to everyone within hearing with the high-pitched screaming they use to attract one another. The female wasp can hear them, too. She makes a bee line (pun intended) for the trees and shrubs where the cicadas are singing their lungs out.
Once she captures one, she stings the unfortunate cicada and carries it back to her burrow. When she has it safely tucked away below ground, she lays an egg on the still-living creature and goes in search of another one. A single female can set up to 16 of these nurseries with one or two cicadas in each. The larva hatches within two weeks and begins to feed on their host. It will then form a pupa and spends the winter in its cocoon.
Cicada killers tend to be active during the mid- to late summer when their prey are abundant. By the end of September, they'll be gone.
Physically imposing, cicada killer wasps won't hurt people unless someone makes the mistake of trying to grab one. Even then, only the female can sting and, considering her size, it's not nearly as painful as one would imagine.
The males do have a pointy bit at the end of their abdomen which they can use to jab you, but it isn't a stinger (don't ask). Males do aggressively protect their territory against other males. They aren't too bright, however, and they'll check you out if you get too close. These inspections can seem to some people to be an attack by a giant killer wasp, but they aren't going to hurt you. In fact, cicada killer wasps are a natural limit on populations of cicadas which, if left unchecked, can do significant damage to shrubs and deciduous trees.
Cicada killers aren't really something you need to "control," but if you're the panicky type, or the nests are located in a bad location (for you, not them), you can do one of two things. Cultural methods work best in the long run. These wasps prefer to place their nests in disturbed areas with little or no vegetation.
A healthy lawn will discourage them from making their burrows. Add a thick layer of mulch to your shrubs and flower beds to discourage them from nesting there as well.
If you want quicker results, you can apply a residual lawn insecticide to the nest entrance when they are actively stocking their brood cells. You also can apply the same insecticide over the disturbed area in early July to kill the emerging wasps and to preclude their building new nests.
As always, if you have a pest problem, contact me here at the Sun Herald.
Tim Lockley, a specialist in entomology, is retired from a 30-year career as a research scientist for the U.S. Department of Agriculture. For answers to individual questions, please send a stamped, self-addressed envelope to Tim Lockley, c/o Sun Herald, P.O. Box 4567, Biloxi, MS 39535.