A week or so ago, I noticed that small mounds of dirt appearing at the edge of the walk to my front porch, and in an area of the garden near my front porch that I had recently mulched. Hmmm..., I wondered, what's going on. Then I noticed a large increase in what I initially thought was bee activity. Turns out that I had misidentified them as bees rather than wasps, because they were not the kind of wasps that make mud or paper nests (i.e., the kind with painful stings).
First I thought I had ground bees, then some kind of wasp, and then, after I lot of searching on the intertubes, I visually and tentatively matched them up with Cicada Killer Wasps. They made quite a mess of my walkway and garden, and of course, I initially had thoughts about extermination.
Dive under the Golden Cicada Carcass for more Killer Wasp information and pictures.
More investigation indicated that Cicada Killer Wasps have a reputation for difficult extermination. Moreover, the Cicada Killer Wasps are not social wasps, meaning:
1. Only one wasp per hole (but many underground brood chambers)
2. The males have no stinger, only fight with other males and cannot sting.
3. The females have a singer but rarely use it for defense, only for paralyzing prey.
I snapped this picture of a male on a bush near my sidewalk.
The male wasp flies around in search of three things: 1) other males to fight with, 2) females to mate with, and 3) food, i.e., nectar from flowers and other plant exudate. Regarding the male's pugilistic propensities, the method of fight consists of locking the bodies of two or three males together (in flight) and flying off in a rather erratic and uncoordinated flight path until they separate. No male dies in these squabbles; however, the issue of territory is temporarily resolved, as only one male returns to the area where the fight started. The cease-fire may last only a few minutes.
The next image consists typical nest hole for a Cicada Killer Wasp except for one thing: In my attempts to dissuade these wasps from lodging near my porch, I've washed away the huge piles of soil the female wasps push up and out of their nest when constructing the tunnels and brood chambers. The following image, taken a few hours after a washout does not show the typical cone shaped pile of soil nor the channel one will see in the cone of soil after the female drags in a hapless (and quite dead) cicada. The hole measures about 5/8 inch in diameter, so the female wasp (much larger than the male wasp) and the cicada are about that size.
Up until today, I've been making educated guesses about these wasps because had a good idea that they were Cicada Killer Wasps. Today I decided to drag out the camera and try to get photographic evidence to compare with online information. I got two giant pieces of information to confirm my identification: Color and thorax stripe information on males and females that matches online images at the University of Kentucky Department of Entomology, and I took pictures of a female wasp dragging a dead cicada into the nest hole.
The next image shows the female wasp near the hole entrance with cicada carcass (belly up) in the hole.
Here is an image of the female wasp doing the hard work of getting the dead cicada and herself into the nest.
When one thinks of cicadas, one often thinks of the cicadas that emerge every 13 or 17 years on some kind of a multi-year cycle. So I did some additional checking, and I found that there exist annual cicadas and the cicadas that exhibit the multi-year cycle. I think the annual ones are not as noisy as the multi-year ones, so they escape notice. However, apparently, these Cicada Killing Wasps in my area are finding cicadas even though we are not in a 13 or 17 year brood cycle, so these must be annual cicadas.
From what I have read about Cicada Killer Wasps, the female will insert a male egg into a single dead cicada, or insert a female egg into a single dead cicada with one or more another dead cicada nearby. This begs the question: How does the female wasp know the sex of the egg? Perhaps it concerns something that only occurs in the bee, wasp and hornet world, where the sex of the species is controlled by the "queen".
The females wasps are much larger and thus will require more food, so they get more cicadas than the male.
The female wasps do all the digging of the nest and all the killing of the cicadas, and they have the task to return the dead cicada to the nest, which I would assume is not easy task, and which lends itself to females being much bigger than the male of the species.
Right now my Cicada Killer Wasp infestation consists of an uneasy truce. I didn't want to kill them, especially because they are not really that annoying (other than being scary to others who don't know the the largest eastern wasp is really quite docile). But the more reading I do about this, I find that this infestation is forming the basis for ongoing infestations in the future. The adults don't winter over, but some form of the animal winters over to form a new generation. I'm worried that they can spread and attack the lawn. I can tolerate a few wasps, as I can always wash the expelled dirt back into the lawn or down the driveway to the street, but I can't handle hundreds of holes in the lawn, which might occur if they spread. Just as the male has only three tasks, the female, outside the nest, has only two tasks: 1) get cicadas, and 2) find new places for holes to dig.
I've read all kinds of stories about control methods that range from:
1. Kerosene torches to burn them coming out of the holes
2. Swatting them to the ground with tennis or badminton rackets, and stomping them
3. Putting poison down the holes and putting clear plastic on the holes at night then removing in the morning
3. Using diatomaceous earth down the hole (dehydrates the female)
4. Boiling water down the hole at night (cooks the female and the eggs)