Lots of websites and newpaper articles state that Periodical Cicada nymphs will emerge, all at about the same time, when their body temperatures reach a certain point. (Various sources say that point is 63, 64, or 65 degrees Fahrenheit.) If that’s true, then we should be able to take the temperature of the soil in our yard, and then predict when the nymphs will start to emerge in our area. Given our try-it-yourself spirit at Kids’ Cicada Hunt, we just had to try taking the temperature of the soil ourselves.
So, about 1 p.m. on Sunday, April 29, we got a large thermometer (designed for elementary school classrooms) and buried it the soil that we had dug up looking for nymphs. (See photo below, dime shows the real size.)
We took the photo after about 20 minutes, when the soil thermometer read about 62 degrees Fahrenheit. After 40 minutes, the temperature was down to about 60 degrees. Unfortunately, we had to give up at that point. We don’t know if the temperature would have continued to fall. Next time we will leave the thermometer buried for at least a couple of hours.
The air temperature was about 78 degrees at that point, so the soil was much colder than the air. According to what we had read in the newspapers and elsewhere, the soil temperature was too cold for the cicadas to emerge, even though the weather above the soil was warm and beautiful.
Now, there are lots of reasons to think our method would produce temperature readings that were a bit too high. For instance, the soil had sat in the sun for a few minutes during digging, and when we packed it around the thermometer, there were still lots of small air spaces where the warm surface air could leak down around the thermometer. So, to check ourselves, we went to Spectrum Technologies’ Cicada Watch 2007 website:
http://www.specmeters.com/cicada_2007/index.html
Spectrum has installed professional quality soil thermometers in the soil at Naperville and Plainfield, Illinois, which are about 25 to 30 miles southwest of our town of Oak Park. Their readings for Sunday, April 29, were about 64 degrees degrees at Naperville and 55 degrees at Plainfield. Because we are closer to the still-very-cold Lake Michigan, we would have expected our soil temperatures to be a bit lower than the Spectrum Technologies thermometers. Instead, we seem to be right in the middle, between two sites with rather different soil temperatures. (The Naperville site seems to be consistantly warmer than the Plainfield one.) So, we are wondering if cicadas will emerge earlier in Naperville than in Plainfield, and if our yard will fall somewhere in between?
We wanted to know how scientists found out that that temperature was the key to cicada emergence, so we went on a kind of science scavenger hunt. We used Web searches to find the actual scientific research study behind all the quotes in newspapers and on the Web. In 1995, cicada scientists Kathy Williams and Chris Simon published a wonderful (but very technical) article describing what scientists have learned about Periodical Cicadas. You can link to their article from this page (go down to paper number 22):
http://hydrodictyon.eeb.uconn.edu/projects/cicada/Resources/reprints.html
Williams and Simon wrote about the research done on cicada emergence. They wrote, ”After examining photoperiod [day length], air and soil temperatures, slope [angle and direction a hill faces], and sun exposure, Heath [1968] concluded that periodical cicada emergence may be triggered when soil and cicada body temperatures at a certain depth reach a critical value” (p. 272-273). The research mentioned in this quote was by James Edward Heath:
Heath, J.E. (1968). Thermal synchronization of emergence in periodical “17-year” cicadas (Homoptera, Cicadidae, Magicicada). American Midland Naturalist, 80, 440-448.
Dad read a copy of Heath’s paper, which he obtained from a university research library. The paper described how Heath studied the emergence of cicadas in southern Ohio in 1965. He measured air temperature and soil temperature at various depths, plus he found a way to measure body temperatures of cicada nymphs that had just emerged from the ground. The body temperatures of the emerging nymphs were almost all between 63 and 66 degrees Fahrenheit. This was about the same as the soil temperature at about 8 inches depth. Like any good scientist, Heath phrased his conclusions carefully: “The most consistent feature of the thermal environment during emergence was soil temperature. The body temperatures of emerging cicadas matched closely the temperature at about 20-cm [about 8 inches] depth. Some temperature characteristic at a 15-25-cm depth in the soil may synchronize emergence” (p. 445). So, Heath didn’t pick a particular temperature as characteristic of that depth, although his data suggest it was from 63 to 66 degrees Fahrenheit for the cicada nymphs he studied.
Because we want to know when our Chicago-area Periodical Cicadas will emerge, we will keep an eye on soil temperature using the Spectrum Technologies website. Also, we probably will stick our own thermometer in the ground a few more times this May.
(We revised this post on May 1.)
Over the last week or so, we have been hearing reports of other folks digging up Periodical Cicada nymphs in their gardens. So, on Sunday, April 29, we decided to try digging in our garden. We found one and a half cicada nymphs (don’t ask…). Below is a photo of the live nymph we found (next to a dime for size comparison):
This nymph SEEMED smaller, a bit narrower, and redder than the Annual Cicada nymphs we have dug up before. Unfortunately, we did not find many confirmed photos of Periodical Cicada nymphs that were dug up early, before their bodies got darker in color. Here is one such link:
http://www.amazilia.net/images/Inverts/Homoptera/Magicicada_septemdecim.htm
Fortunately, Roy Troutman took a look at our photo and used the comment section to correct our preliminary identification. He says it is most likely one of the Annual Cicadas (scientific name Tibicen) rather than a Periodical Cicada (scientific name Magicicada). He based his identification on the overall shape and the lack of color in the eyes.
We will try digging again in a few days and see if we find the real thing.
If you have been following along with our hunt for Periodical Cicadas this year, you may remember that we first tried digging for Periodical Cicada nymphs back on April 1. However, that day also, all we found were Annual Cicada nymphs that appeared to be left over from last summer. Go here to read about our finds on April 1:
http://www.saltthesandbox.org/cicada_hunt/PeriodicalHunt2007.htm#FIRST_NYMPH
Science doesn’t have to be a spectator sport! Citizen-science projects let ordinary folks do science in the big leagues, managed by the pros.
We just discovered a new citizen-science project about periodical cicadas run by the Lake County Forest Preserve District. “Those living in the region of the 2007 emergence are invited to contribute valuable information to the forest preserve district’s cicada emergence mapping project….Citizen scientists are asked to visit an online interactive map and place a map pin at their home or work address to indicate the density of cicadas in their area.” Soon, the Interactive Online Emergence Map will be available on the Forest Preserve District’s website: www.LCFPD.org/cicadas Our advance information came from the following Web page:
http://www.lcfpd.org/index.cfm?fuseaction=home.details&intObjectId=25286
The Lake County Forest Preserve project seems like just the right kind of citizen-science program for our family. It’s web-based, and we can do it from home — just like Project FeederWatch, which we have done for the last three winters. (Go here to find out more about Project FeederWatch: http://www.birds.cornell.edu/pfw/Overview/over_index.html )
See our April 10 blog post to read about a another citizen-science project, focused on DePage County (west of Chicago). Or, you also can follow this link: http://tom.dupageforest.com/video/cicadacitizen.html
Thanks to everyone who wrote us, through blog comments or by e-mail! We’ve enjoyed reading your stories of cicadas in the past, and we are encouraged to hear you’ve dug up nymphs this spring. (See the comments section under the 4/21/07 posting to read some of them.) Once this week’s storm has passed, we will get out our shovels and dig some more in our garden. We are anxious to see what we turn up.
Our anxiety comes in part because one of our neighbors, who pays close attention to these things, says she did not see many cicadas in her yard in 1990. Her family found lots of them on a trip to Brookfield Zoo, but came up short in our neighborhood. So, it seems like time to conduct another a subterranean cicada census on our block. We’ll let you know what we find.
Also, we have been bad scientists, because we have not revealed our negative findings: We have not told you about all the places we have NOT seen cicada burrows reaching the surface. We have looked for, but not found, burrows in our yard and in many other yards in Oak Park. We also have not NOT found burrows on recent birding trips to Columbus and Douglas Parks in Chicago, The Grove in Glenview, the Mission Hills area in Northbrook, or Chicago Portage near Lyons. But we will keep looking….
Periodical cicadas have been getting lots of bad press this year, and we’ve read lots of blog posts expressing people’s dislike and fear of cicadas. So, we were thrilled when Beth Botts–one of our heros of this 2007 Year of the Cicada–published an article, entitled “Cicadalove,” this past Sunday. As Beth wrote, “The 17-year visitors may be noisy and annoying, but your plants won’t really mind — and you shouldn’t either.”
Go here to read Beth’s article, plus many more Tribune features on cicadas:
http://www.chicagotribune.com/features/chi-cicadas-specialpackage,0,3599101.special
(By the way, we would have loved Beth’s article even if she had not interviewed us!)
…who have lived in our neighborhood for more than 17 years. They said there WERE periodical cicadas in our neighborhood in 1990–lots of them! However, they also had stories about seeing even more cicadas in other places, like Elmwood Park.
So, we know we have something to look forward to in our yard this May!
While preparing for an interview with a reporter from the Chicago Tribune, I made a list of all the things that the boys and I want to accomplish during this year of the cicada:
1. Right now, we are mostly trying to find the earliest examples of everything we can related to periodical cicadas. We want to find the earliest burrow, nymph, and adult, and hear the earliest songs. You can see photo-stories about our finds on this page:
http://www.saltthesandbox.org/cicada_hunt/PeriodicalHunt2007.htm
2. We want to talk to people who have lived in our neighborhood for more than 17 years. They may be able to tell us what we can expect around here when the cicadas emerge. Based on our neighbors’ 1990 experience, can we expect a lot of cicadas, very few, or none at all?
3. Once the cicadas start emerging, we want to see and hear it happen. What time of day will they emerge? When will they start to sing?
4. My kids are really into birding right now, so we will probably keep records of all the birds (and other animals) we see eating cicadas.
5. What types of periodical cicadas are in our neighborhood? The scientists suggest we may have three different kinds. We will use appearance and songs to tell them apart.
6. We also hope to do some counts of emergence holes on the tree lawn in front of our house. There is a large American Elm tree here, and we can imagine that lots of cicada nymphs have been sucking on its roots for the past 17 years. If we come up with a good way to count holes, then we can compare what we find with what cicada scientists have recorded in their studies.
7. We want to look for insects that specialize in eating cicadas, or in feeding them to their young–like Cicada Killer Wasps and Sandalid beetles. Most years we only see these insects in July, August, and September. Will these cicada-eaters come out early this year?
8. We will try to find the eggs (laid in live twigs) and the babies (which fall to the ground when they hatch).
9. I bet Ethan will want to cook and eat a few cicadas, but we’ll have to do that when Mom isn’t around.
I’m sure we will think of more things to look for and to do this year. We’ll let you know when we do–or you can make your own suggestions!
For an expanded version of this list, with lots more links, go here:
http://www.saltthesandbox.org/cicada_hunt/ThingsToDo.htm
We’ve posted our story about the burrows we found on Saturday along the Des Plaines River, with photos, on our Kids’ Cicada Hunt website: http://www.saltthesandbox.org/cicada_hunt/PeriodicalHunt2007.htm#MORE_BURROWS
Again, these burrows were not exact matches for periodical cicada burrows/ But, since it’s 2007, and the cicadas are coming, you’ve got to wonder.
On Saturday, April 14, the boys and I were birdwatching along the west side of the Des Plaines River, just south of Joliet Road. (We think this is in Lyons, Illinois.) While walking through a thicket just west of the park road, we noticed lots of holes in the dark, muddy floodplain soils. The holes were openings of deep burrows. They were about the same size as the ones we found on Easter Sunday (smaller than a dime). However, these burrows did not have mud caps or chimneys. A few had just a bit of mud built up on their edges, and a few seemed to have mud linings that were a slightly different color than the surrounding soil. A few were crumbly at the edges, as if something had tried to dig down from the surface.
So, were these periodical cicada burrows? Crayfish? Something else? We’re not sure. We’ll post photos in a day or so.
We also flushed a woodcock in this thicket. Woococks have long beaks that they usually use to eat worms and other soil animals. This got us wondering–maybe the woodcock had been sticking its bill down these holes, trying to fish out whatever was in there.
If you want to become an official cicada hunter for the Forest Preserve District of DuPage County, Illinois, then sign up for their “Cicada Citizen Science” program. As cicada citizen scientists, county residents can help the Forest Preserve District map where cicadas live in DuPage County. There will be an an informational session on Saturday, May 12, from 10 a.m. to Noon, at Fullersburg Woods Nature Education Center in Oak Brook. Reservations begin April 30. For information, call (630) 850-3722, or go here for information, data forms, and a video: http://tom.dupageforest.com/video/cicadacitizen.html
We live in Cook County, so we will probably remain unofficial cicada hunters. Still, it seems like a great program!
We’ve posted our story, with photos, on our Kids’ Cicada Hunt website:
http://www.saltthesandbox.org/cicada_hunt/PeriodicalHunt2007.htm#FIRST_BURROW
As we posted yesterday, these burrows are not exact matches for any photos we have found of periodical cicada burrows, but we would not be surprised if they were the real thing.
We checked the rocks in the front garden this morning — no sign of cicada nymphs or their holes in our yard. Then we drove north to Glenview, Illinois, to celebrate Easter with the Gyllenhaal side of our family.
While waiting for Easter dinner, the boys and I went exploring in the small woods across the street from my sister’s house. We started turning over logs, and with the fourth log, there they were: Openings from deep vertical tunnels, a bit smaller in diameter than a dime. That’s the right size for the burrows of at least one kind of periodical cicada. A few tunnels at the edge of the log were covered by rounded caps of dried mud. At least one of the caps was fresh, moist soil. Looking around the woods, we found more mud-capped burrows among the dead leaves.
The articles and Web pages we’ve read talk about how periodical cicada burrows are often topped off with “mud chimneys,” “mud tunnels,” or “turrets” of dried mud. These mud features all seem to have an opening at the top. Check the following pages for photos that others have taken of these features:
http://bugs.osu.edu/~bugdoc/PerioCicada/PeriCicadaBehav.htm (Look about 2/3s of the way down the page. We found mud caps in similar positions at the edges of logs, but ours were sealed shut)
http://cicadamania.com/gallery2.html (See the “mud tunnel” photo. This is much taller than what we saw, although the surface texture is similar.)
The dried mud covering our burrows was much more like a rounded cap–there was no opening at the top. So, we didn’t find an exact match for anything we’ve seen on the Web. But then, conditions today were pretty different from when the Web photos were taken. We found the burrows in early April, at least five or six weeks before the cicada emergence is expected around here, and it has been cold for the last several days–below freezing in the mornings. Are the mud caps a way the protect periodical cicada burrows from the cold?
Oh, one more thing. In the week or so before emergence, the cicada nymphs are supposed to lurk in the tops of their burrows. We didn’t see a single nymph today–just the burrows.
We will post photos and more description on the Kids’ Cicada Hunt website sometime tomorrow.
I just updated the Kids’ Cicada Hunt page that has information about Chicago area exhibits and progrmas about periodical cicadas: http://www.saltthesandbox.org/cicada_hunt/ExhibitsPrograms.htm
There is more information about the exhibit that opens April 21 at the Notebaert Nature Museum in Chicago, plus new program listings for April and May.
Back on April 1st, I posted a link to a page looking at visits to the Kids’ Cicada Hunt website over several years:
http://www.saltthesandbox.org/cicada_hunt/Usage.htm
For comparison, here is a Google Trends page that shows how many Google users entered the search term, “cicadas,” over several years:
http://www.google.com/trends?q=cicadas&ctab=0&geo=all&date=all
The graph shows a huge jump in “cicadas” searches in 2004, when periodical cicadas emerged all over the Eastern United States. However, this Google feature seems pretty insensitive to small-scale changes in search patterns (use the slider below the chart to see 2007). It hasn’t picked up any change so far this year. We’ll see what happens in May and June of this year, though.
Here’s a totally different approach to looking at cicadas on the web. This feature at Technorati.com tracks how many bloggers included the word “cicadas” in their postings:
http://technorati.com/chart/cicadas?chartdays=90&language=n&authority=n
If you set this for 90 days, you can see an increase in postings in March of this year. This coincides with a bunch of articles in Chicago-area news outlets about the Ravinia music festival’s schedule changes, which were in response to this year’s anticipated emergence. Again, it will be interesting to see what happens in May and June.
We’ve posted our story, with photos, on our Kids’ Cicada Hunt website:
http://www.saltthesandbox.org/cicada_hunt/PeriodicalHunt2007.htm
As we posted yesterday, we’re pretty sure the live nymph we found is an annual cicada.
Today, April 1, we found our first live cicada nymph of 2007. Unfortunately, we’re pretty sure it was an annual cicada, not one of the periodical cicadas that we are hunting for this spring.
Here’s a quick summary of what happened. Within a day or so, we will add a page to Kids’ Cicada Hunt with photos and details.
My wife had asked us to dig up some perennials from our front garden, which is under the canopy of the 75-year-old elm tree. As we were starting to dig, we found lots of shed annual cicada skins from last summer, plus the usual earthworms, pillbugs, millipedes, beetles, and beetle larvae. Finally we found some cicada nymphs in the soil, but they turned out to be mummified. They had died without emerging, and their bodies had somehow dried out (or maybe freeze-dried) and then survived, partly decayed but uneaten by scavengers, until we found them.
And then, as we were digging under some of our garden rocks, trying to get the last of the perennials’ roots, we found a live cicada nymph. It was very pale, more yellowish than brown, as seems typical of cicada nymphs we excavate from the soil. However, it was also the same shape and size as the annual cicada nymphs we find every summer. The periodical cicada nymphs we have seen were shorter and narrower and were usually reddish (especially in the eyes).
We’re not sure if our live nymph tried to emerge late last summer and didn’t make it (maybe because of the rocks that cover the soil there), or if it was getting ready to emerge later this summer. But we are pretty sure it is NOT a periodical cicada nymph working its way to the surface for this spring’s emergence.
So, our hunt continues….
We’ve got digital photos, which we will post within the next few days.
Here’s the link to a different kind of story, about how visits to our Kid’s Cicada Hunt website change with the years and the seasons, as cicadas and their predators emerge, do their thing, and die off:
http://www.saltthesandbox.org/cicada_hunt/Usage.htm