During the past few days, I have received several phone calls from people asking about strange-looking mounds of dirt in their yard. Then yesterday, I went home from work to find a strange-looking mound of dirt in my own yard.

As I talked to those that called, and even as I saw the mound of dirt in my yard, my first thoughts were that it was caused by fire ants. But all of those calling were like me. We all have had a lot of experience with fire ants, much of it unpleasant, and we know fire ant mounds when we see them.

My recommendations to those who called were proven correct when I saw the mound of dirt in my yard. No, they were not caused by fire ants. They were caused by cicada killer wasps.

Anticipating that some people who might read this column will see strange-looking mounds of dirt in their yard during the next several weeks and others reading this column might just find this information interesting, I decided this might be a good time to share more information with you about cicada killer wasps.

Let me tell you about cicadas first. Cicadas are those large bugs with big eyes, shaped like a bomb, with large transparent wings. They are also the things that emerge from the shells we often find attached to the side of a tree, post, or wall and, as kids, we collected and hung on our shirts like badges or ornaments. These insects first emerge from the ground as a nymph and crawl up the side of a tree or some other surface. They then molt into the adult stage, leaving the skin or exoskeleton behind. The adult flies into nearby trees to feed and mate. In order to attract a mate, they emit a loud, buzzing song which is not too annoying when there is only a couple of cicadas around. But when there are thousands of them, each trying to outdo the other to attract a mate, the noise can be so annoying that people sometimes have to seek peace and quite inside.

Cicadas are often referred to a periodic locust, even though they are not locust at all. Locusts are actually insects resembling grasshoppers that have plagued mankind since Biblical times.

There is a particular wasp that feeds entirely on cicadas and can be found wherever cicadas are found. Naturally, the name of this wasp is the cicada killer wasp.

Cicada killer wasps are rather large when compared to most of the wasps we see in this area. They often grow to almost two inches long. The are mostly black, with bright yellow markings. Although the female does have a very fierce-looking stinger, it will rarely sting even if provoked. Males, like the males of other species of bees and wasps, do not have stingers.

What is annoying about the cicada killer wasp is that it is a digger-type wasp. The females dig deep holes into the ground in which to lay their eggs instead of building a hanging nest like other wasps. Considering the size of the wasp and the fact that such a deep hole is dug, you can imagine the amount of dirt that must be excavated in order to create nesting holes. The mounds of dirt created by these wasps is what those calling my office were asking about. It was also what I saw in my yard.

After the wasps creates her nest in the ground, she then flies off in search of a cicada. When she finds one, she stings it, not to kill it but to paralyze it. She then carries it back to her nest. Cicadas are large insects, and sometimes they are larger than the wasp that captures it. In these cases, the wasp has a lot of difficulty getting the cicada back to her nest, and it is rather interesting to watch her try. After capturing the cicada, she will leap from the tree and glide and fly as far as she can. If she is not close enough to her nest, she will climb the nearest tree and leap out again, gliding and flying toward her nest. She will repeat the process until she gets close to her nest and will then drag the paralyzed cicada the rest of the distance.

The cicada killer wasp uses the cicadas she captures to provision its nest. Once in the nest, the female wasp lays her eggs on the cicada. Soon wasp larvae hatch from the eggs and feed upon the cicada. When mature, the wasp larvae pupate and another generation of wasps emerge to carry on the life cycle.

Since these wasps feed on annoying cicadas and since they rarely, if ever, sting, they are considered to be beneficial. Therefore, I would encourage you to leave them alone unless they are doing a lot of damage to your yard.

If you feel you must control them, the best strategy is to use an old tennis racket or boat paddle. Stand very still, close to the mound, and when the wasp hovers over it, practice your swing. This works almost every time. Since they are solitary wasps, you will probably have the opportunity to practice your swing only once.

If you feel you must use an insecticide, virtually all of the commonly used products, such as malathion, diazinon, and orthene, are very effective. Mix a small amount in a watering can or bucket, and when the wasp enters the hole, pour the solution in behind her.

Now you know the mystery of the strange mounds of dirt.

E-mail address: Everett_Davis@ncsu.edu

Mailing Address:
P. O. Box 2280
Lumberton, NC 28359-2280

Phone: 910-671-3276
Fax: 910-671-6278

Date Created 8/22/03