Just after we are done with the periodical cicadas, we will start to see cicada killers.
Not killer cicadas -- surely by now everybody has the T-shirt: Cicadas are harmless to people. But there is a cicada killer wasp, Sphecius speciosus, which needlessly scares the bejabbers out of some people. It kills a completely different kind of cicadas.
There is little more reason to fear the wasps than there is to fear cicadas. They are not aggressive. And don't hope for them to stop the late-May swarm of periodical cicadas. That's because eastern cicada killer wasps won't emerge until the periodical cicadas are pretty much history. Cicada killer wasp larvae feed instead on dog day cicadas -- which are around every summer and don't even appear until July.
Cicada killer wasps can be frightening because they are very large, well over an inch long, and the males often are found flying around lawns in large numbers. But the males can't sting (though they may try). The females can, but are difficult to provoke. Joe Coehlo, a biology professor at Quincy University in Quincy, writes on his Web page that most people who think they have been stung by cicada killer wasps have probably been stung by European hornets.
"They are wonderfully gentle animals, unless you grab them and hold them down," says biology professor Chuck Holliday at Lafayette College in Easton, Pa. A sting, he says, feels rather like a Novacaine shot. (He is looking for cicada killer wasps and cicadas caught by the wasps from anywhere in the country; if you are willing to help him, e-mail him at firstname.lastname@example.org.)
The wasps don't hurt the lawn or other plants; during their month or so as adult insects, they feed harmlessly on nectar and tree sap. Once they hatch in about mid-July, males find a female and often pile all over her to mate (it's called a scrum, like in rugby). With sperm aboard, the female will capture a dog day cicada, paralyze it with her stinger and drag it down into a burrow where she lays an egg in it. She adds sperm to make a female or withholds it to make a male.
The egg will hatch into a grub that eats the cicada (alive!) and weaves itself a cocoon to overwinter in. The next summer, it will emerge from the ground as a wasp.
The burrows are what annoys lawn fanatics. The wasps prefer disturbed ground to dig their holes and our yards fit the bill. Lawns that are cut too short are especially tempting to them. So one of the best defenses is a practice that is good for the lawn anyway, because it holds in moisture, encourages deep roots and discourages weeds: Mow high. Keep your lawn at 3 inches and it will be far less tempting to cicada killer wasps.
If you do find wasp holes, don't worry about them. The holes don't harm the lawn, and the dirt piles next to them will disappear in a couple of rains. Think of it as beneficial aeration.
There is no need to kill the wasps, although if you feel irrationally compelled to try, Coehlo's Web page will tell you how difficult and futile it is.
In fact, experts agree, the best thing to do about cicada killer wasps is leave them alone. "Usually the perceived need for control is based in fear rather than fact," says the Web page of the North Carolina Cooperative Extension.
Holliday has a fascinating and detailed page, including lots of pictures of cicada killer sex (how's that for a name for a band?) and scrumptious video of a cicada killer wasp larva eating a cicada.
Photo: Cicada killer wasp (Sphecius speciosus). Courtesy of Chuck Holliday, Lafayette College, Easton, Pa.
Thank you for the helpful article. I don't mind the cicada killers digging holes in my yard, my big fear is them stinging my dogs. One of my dogs sometimes likes to chase bees and wasps. Do you know if cicada killers tend to go after dogs?
Posted by: Sue | Jul 29, 2007 1:52:15 PM
They don't. Cicada killer wasps don't go after anything except cicada killer wasps of the opposite sex (and, as appropriate, dog-day cicadas). It sounds like your dog is the one going after them.
Posted by: Beth Botts | Jul 29, 2007 11:44:10 PM
Even if he or she catches a cicada killer wasp, though, I wouldn't worry about it. The ones commonly seen flying around on lawns are males, which don't even have stingers. Female wasps can sting, but they are not aggressive; bites are very rare. I have not been stung by a cicada killer wasp personally, but from what I have been told a sting is mildly unpleasant but not dangerous (unless you are allergic to insect bites).
It doesn't sound to me like something to worry about, but if you are concerned, my best suggestion would be to restrain the dog until the wasps are gone in two or three weeks.
We have a nest that appears to be under our patio. Can these Cicada killers be so destructive as to undermine the foundaton of the patio? How deep are the burrows? Do they come back to the same place the next year?
Posted by: Cindi | Aug 4, 2007 9:23:39 AM
No, they won't undermine your patio. The burrow is less than a foot deep and contains only one wasp. The insects are solitary and they don't form colonies. They tend to stay in the same general area, if it offers a good supply of dog-day cicadas to capture and lay eggs in. But they don't return to the same burrow year after year.
Posted by: Beth Botts | Aug 5, 2007 12:23:41 PM
If the nest really freaks you out I guess you could pour boiling water dsown the hole to kill the wasp. But personally, I would just leave it alone and not worry about it.
I have about 8-10 burrows around the edge of my lawn (in the space between the street and the sidewalk near the curb & a few more on my lawn proper). Does this mean that there are 8-10 wasps or is one possibly relocating to each mound for some unknown reason?
Posted by: kathryn | Aug 6, 2007 12:30:17 PM
Up here in Michigan we have cicada-killer wasps that don't fit the popular behavior profile, in regard to aggressiveness of females.
These females are close to 2 inches long, and will buzz people with less aggressiveness than the males, which will flat drive you out of the area.
I know this because I have personally been buzzed repeatedly and then attacked by a female just 2 days ago on Aug 15... I believe the fact that the insect was carrying a cicada at the time (confirmed after I slapped the darn thing out of the air) confirms the sex as female.
I have been driven away from areas of our blueberry farm by what I assume are males, given the aggressive behavior, so the attack by the female not only surprises, but makes me wonder if all the other attacks were by males...
You can put all the "irrational fear" theories to rest, since I had been told by some misinformed person that they were "pine borers", and had no real reason to fear them at the time of the attacks.
I have seen arrogant statements made by academics as to the possibility that persons had been stung by bumblebees, etc. How could any human capable of LANGUAGE mistake a bumblebee for a cicada-killer? This suggests narrow vision in the academic, aimed squarely down the nose.
I am particularly interesed in this sort of thing since I have developed a deadly allergy to stings from most Hymenoptera species.
Posted by: cjinsomniac | Aug 17, 2007 11:39:38 PM
We have had Cicada killer wasps for 3 years, and have had a "live and let live " attitude until now. The last 3-4 days we have noticed that some nocturnal animal is digging up the wasp nests... and each morning there are more very large holes in the lawn and garden, this morning one even was so deep as to expose the roots of the bush nearby.
Posted by: Amy | Aug 20, 2007 9:47:11 AM
HAs anyone an idea what might be digging up the nests, and more improtantly how to stop THIS behaviour? It is really getting quite messy out there.
This is a conjecture, Amy, but if your yard is anything like my yard my guess is it's opossums or skunks. They are insectivores that are very well adapted to urban and suburban settings. (We have had possums for years; they live under the next-door neighbor's hot tub.) I don't think there's anything you can do to get rid of these mammals. It's probably best just to wait until the wasps are gone and then reseed that part of the lawn.
Posted by: Beth Botts | Aug 20, 2007 11:50:46 AM
Cicada killer wasps prefer to dig their holes in areas of bare or disturbed earth, so covering the earth with healthy lawn or mulch likely will discourage them (next year, anyway). Then there wouldn't be buried wasps for possums or skunks to dig up.
We recently found 2 of these wasps in my kids pool. (they were dead of course). anyway, I picked one up and showed my husband and he didn't know what it was. Of course after lots of looking on the internet we figured out what it was. We live in west central Arkansas. Are these common to this area? Have they always been here and we have just never had a run in or ever noticed them? Most of the web sites say they are common east of the Rockies. Almost everyone in this area that I have shown it to does not recognize it. Can anyone answer some of my questions?
Posted by: kelly | Aug 26, 2007 1:40:33 PM
Kelly, My suggestion is that you get in touch with Prof. Chuck Holliday at Lafayette College, who is an expert on cicada killer wasps and whose e-mail is in my original post. (Also in the post is a link to his informative cicada killer wasp page.) He probably would answer your questions; he was very kind about answering mine.
Posted by: Beth Botts | Aug 26, 2007 11:22:00 PM
I know nothing about Arkansas insects, but my guess is that they've been there all along and you just never noticed.
this was an awesome page of information...I went to the service and came back and all of these holes were in my lawn...I totally freaked out when I saw this gigantic bee like insect. (laughing) thanks for the insight.
Posted by: tiffany bowers | Aug 28, 2007 3:30:46 PM
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