Here in south Oak Park, Illinois, we just heard our first Annual Cicada, a Tibicen pruinosa, singing about 45 minutes before sunset. (Sorry, cicada species don’t have common names.) Go here to see and hear examples of this species:
http://insects.ummz.lsa.umich.edu/fauna/michigan_cicadas/Michigan/Index.html#Tibicen_pruinosa
Last year we heard our first Tibicen pruinosa on June 27, although for several years before that we did not hear them until early July. Here is a page with some of our records for first and last dates for Annual Cicadas: http://saltthesandbox.org/cicada_hunt/DatesFound.htm
The Periodical Cicadas are still barely hanging on around here. We are finding lots of wings and partly eaten bodies, but seeing and hearing very few live ones. Actually, we have been feeling seriously deprived of Periodical Cicadas in our neighborhood. We have to drive a few miles west, to the forests of the Des Plaines River floodplain, to see them in large numbers. At least we seem to be a bit ahead of the game with the Annual Cicadas!
We have been falling way behind on cicada blogging, partly because Dad has lots of deadlines at work, and partly because the kids are much more interested in birds than cicadas this year. Eventually we’ll catch up, though–we do have a few stories to tell.
Dad was out of town all last week, so we were afraid we were going to miss the peak emergence of Periodical Cicadas in our area. Fortunately, the emergence seems to be just starting at Chicago Portage, where we like watch both birds and cicadas.
On Sunday, May 27, we walked along the edges of the woods and on the gravel path that winds through the woods and past ponds that fill an abandoned channel of the Des Plaines River. We found only a few cicadas still emerging from their nymphal skins, with tiny un-inflated wings, like this one:
And we found a few cicadas that had emerged a few hours earlier. Their wings were fully inflated, but they were still white in color:
We mostly found hundreds of shed skins of nymphs, like the ones above, and hundreds of adult cicadas resting on plants:
We also found quite a few cicada wings on the paths through the forest. When we got to the open area close to the water, we found out how the wings got there. We saw an American Robin behaving like a flycatcher, twisting and turning through the air to catch a flying cicada on the wing. We also saw Common Grackles, Starlings, Orioles, and some sort of real flycatcher eating adult cicadas.
We did not hear any cicadas singing. That should start in a few days.
Almost all the shed skins and adult cicadas were at the sunny edges of the woods and in sunny openings between the trees. That means there are still thousands of cicada nymphs–maybe hundreds of thousands–still in their burrows in the deep woods, with its cooler soil. Waiting, for another day or two. Then the REAL emergence should begin at Chicago Portage!
We still have found NO Periodical Cicadas on our block, although we’ve heard reports of them from elsewhere in Oak Park. Maybe we will do a tree-by-tree search tomorrow.
We had been reading online reports of Periodical Cicada adults emerging by the hundreds on Saturday night in towns like Brookfield and LaGrange Park (see earlier post, below). So, Dad went over to Brookfield on this cool morning (mid 40s — the kids had Sunday school, so they couldn’t come). He searched a quiet suburban neighborhood southwest of the intersection of Prairie and the railroad tracks.
He found dozens, but not hundreds, of shed cicada skins on trees, fences, and other upright surfaces.
There were also dead nymphs and a half dead adult on the sidewalk, plus some cicadas that died while shedding (which we brought home to photograph).
The House Sparrows were fighting over some of the remains.
It seems like a rough life for Periodical Cicadas, especially for the first ones that emerge. It will get warmer again on Monday, and stay warm for the rest of the week. So we’ll see what happens then….
Not that my family has seen adult cicadas, though :-( We went to Chicago Portage last night and saw a bit of shed skin and a reddish nymph, but no adults were emerging there.
Then, this morning we woke up to find an e-mail from Kathy in LaGrange Park, Illinois. She wrote, “I’ve spent two nights in my garden with my kids watching hundreds of white cicadas emerge from their shells.”
A quick search of Technorati.com turned up a blog with no location information, but with a report that one of her sons counted 700+ cicadas! Her post later on May 20th includes a cool home video and some still photos.
http://deedlebomb.livejournal.com/
Mari reported on CicadaMania that cicadas were emerging in some places in Brookfield, but not in others: http://www.cicadamania.com/message-board/hello-world/#comments
After we posted this, we started getting comments from other folks who have seen huge nunbers of cicadas emerging. So, be sure to read the comments section, below!
So, the Emergence of 2007 really seems to have begun, but in a kind of spotty way.
The rain is gone, and it’s starting to warm up again! Although other folks have reported finding a few adult Periodical Cicadas in northern Illinois, so far we have found only burrows and nymphs. Actually, we haven’t found that many burrows on our block. So, we have been visiting forest preserves along the Des Plaines River to conduct our daily cicada searches. Usually Dad stops by the preserves during the day while on work-related trips. On Friday night, Ethan, Aaron and Dad made their first after-dark cicada hunting trip.
Since we have no adult cicadas to show you, we’ll show you some of our favorite photos of burrows and nymphs. We are particularly impressed with the nymphs’ ability to burrow through things they encounter as they dig to the surface. For instance, here is a burrow that penetrated right through a dead cottonwood leaf on the forest floor:
If that photo doesn’t impress you, try the following ones. A bunch of cicadas burrowed up through the soil (lower part of first photo) and encountered a rotton log. The rotten wood was wet and soft, so they kept on going. They burrowed up through the bottom of the log (top right of upper photo), then out the top of the log (lower photo, dime shows the real size).
The nymphs can’t burrow through anything really tough, like rock or fresh wood, but we still were impressed.
Here’s a photo from our first night hunt for Periodical Cicadas. Since no nymphs had emerged on their own, we found some by carefully turning over small, rotten logs:
After looking at the cicada nymphs, we carefully place then back in their burrows, butt first, before gently putting the log or rock back in place. We try to leave a bit of extra space at the edges, so the nymphs will be able to escape when it’s finally time to emerge. By the way, Ethan gets extra credit in science class if he produces evidence of Periodical Cicadas for his teacher. We’re not sure if this counts.
To be fair, here’s a photo of Aaron:
Aaron looks pretty happy! Would you believe he has worked hard to overcome his innate squeamishness about bugs? He still does not like to touch some bugs (like crickets), but he does really well with cicadas.
If your kids are having trouble with cicadas and other bugs, you should check out this article, entitled “Helping Children Enjoy the Cicadas,” written for the 2004 Periodical Cicada emergence in the Eastern United States. A few of the links no longer work, but the article itself seems really useful. (It even links to our site!)
That’s it for tonight. We hope to find adult Periodical Cicadas within a few days!
Here’s the quick update: We have been finding lots of new cicada burrows, which may be linked to the recent rains. We have found no adult cicadas, perhaps because it has been so cool.
Here are the details: The last few days have been wet and increasingly cool here in the Chicago area. The rain seems to be ending this morning. Today the sun is supposed to return, and temperatures will rebound slightly, from the current 40s to about 60. On Friday temperatures are supposed to rise into the 70s and maybe reach the 80s on Saturday.
Why does weather matter? Two things seem to be important. First, as reported in many online sources and elsewhere, Periodical Cicada nymphs emerge from their burrows and become adults when the temperature of their soil reaches a critical value (about 64-65 degrees Fahrenheit). According to soil thermometers linked to Spectrum Technologies’ Cicada Watch 2007 website, soil temperature as been hovering near 65 degrees for the last few days. Perhaps with the coming warm spell, soil temperature will reach the critical value and the mass emergence will begin.
The other thing that seems to matter is soil moisture. The morning after the rain began, we found burrows in places where we had not seen them before. For instance, we saw many new burrows in the grassy margins of the woods at Chicago Portage, on Harlem Avenue just north of Interstate 55, on the Des Plaines River floodplain. As reported here on May 15, before the rain we found just a few burrows in the grassy margins of the woods (compared with thousands under leaf litter in the adjacent woods). On Wednesday morning, we found a few new burrows in the grass under trees where we had searched the day before. By Wednesday afternoon, there were even more. We will check again today to see if this trend has continued. We also found one or two more burrows in the lawns near our home, but nothing like what we are seeing at Chicago Portage.
What began this spring as just a cicada hunt has evolved into a search for answers. Why have we found so few cicada nymphs and burrows on our block? As detailed in our earlier postings, we have come up with four possible explanations, which we are testing as hypotheses.
Hypothesis 1: Maybe our block is overbuilt. Maybe we have few Periodical Cicadas because our block has much more space devoted to streets, sidewalks, and houses than to tree-covered lawns. To test this hypothesis, we searched a nearby park for cicada burrows. There were no houses and few sidewalks in the park, but we found no more burrows there than here. So, this hypothesis may not explain our situation (at least not by itself).
Hypothesis 2: Maybe our block is former farmland. Maybe we had Periodical Cicadas here until about 175 years ago, but then they all died out as the area was converted to farms. We need maps or photos from the past to test this hypothesis, and we have not had time to look for them yet. So, this hypothesis is untested.
Hypothesis 3: Maybe our block is former prairie. Maybe there were few Periodical Cicadas here even before European farmers moved in, because our area was mostly prairie back then. Periodical Cicada nymphs suck on tree roots, but prairies don’t have many trees. To test this hypothesis, we looked for burrows in nearby areas that were forested when European settlers arrived. So far we found lots of burrows on the Des Plaines River floodplain, but no burrows in a park at the south end of what used to be a wooded ridge. So, this hypothesis seems partially supported, but it may not explain everything.
Hypothesis 4: Maybe our block has too much mowed, grassy lawn. Maybe the current vegetation is what matters, and mowed grass somehow limits the number of cicada nymphs or limits the number of burrows that reach the surface early in the spring. This hypothesis was inspired by our observations at Chicago Portage. Earlier this week, there were lots of burrows in the woods, but almost no burrows in the nearby grassy areas. However, once it started raining, this began to change–there were increasing numbers of new burrows appearing in the grassy areas. For an additional test, we looked at grass-free gardens and bare spots in our neighborhood and found only a few burrows there. So, this hypothesis may not explain our block’s cicada-deprived situation either (at least not by itself).
The evidence so far provides partial support for the former-prairie hypothesis, and less support for the overbuilt and too-much-grass hypotheses. We don’t have a complete answer to our question, but we seem to be moving in the right direction. We will keep gathering evidence and let you know what we find.
Here’s a report from our comments section by Homeschool Mom:
“On Monday night 5/14, my friend in Hillside returned home for the evening around 11:00 p.m. There on the bricks of the house next to the door was a cicada nymph shedding it’s skin. They video-recorded the whole thing! It definitely had the red eyes and was a periodic cicada. We haven’t seen any more since then, but it has gotten colder again…”
Since Wednesday night was so rainy here in Chicago, we dug around online instead of outside. We found the following online reports of adult cicadas:
In an article written for the Brookfield/Riverside Landmark, Chris Stach reports finding a single early-emerging cicada “along the Salt Creek Bicycle Trail, just west of the Indiana Harbor Belt underpass, on May 8. It hopped down in front of me and didn’t make a sound.”
On May 18, Kim reported finding a few emerging and emerged cicadas, but it turns out she lives in Oregon. She found one of that state’s versions of Annual Cicada. Go to the Chicago Gardener blog run by Tribune reporter Beth Botts, and look near the bottom of the page.
The Lake County Forest Preserve District:’s Interactive Online Emergence Map has pins scattered around Chicagoland, but these have no dates attached.
I’d like to see some confirmed photos of Periodical Cicada adults with both dates and locations. So far, no luck with this.
Once it warms up around here, we expect Periodical Cicadas to crawl out of their wet burrows, head for the nearest upright plant stem or tree, shed their skins, and grow their wings. We’re betting (or should we say hoping?) that the 2007 emergence will begin this weekend. So, here are some things that YOU can do when you find your first adult cicada:
You can post a comment by clicking on the link at the bottom of this post. We always enjoy reading them!
You can stick a pin in the Interactive Online Emergence Map.
This citizen-science project is run by the Lake County Forest Preserve District:
http://www.lcfpd.org/cicadamap/
You can report it on Cicada Mania
Go to the Cicada Mania Message Boards, here:
http://www.cicadamania.com/message-board/
You can tell your story to the Chicago Tribune’s pro-cicada garden blog.
The Chicago Gardener is run by Tribune reporter Beth Botts.
http://featuresblogs.chicagotribune.com/chicago_gardener/2007/05/tell_us_your_ci.html
You can take its picture and post it to The Cicada Project.
This is a project of the Homer Township Public Library. While the library waits for the real thing, they are being visited by jade cicadas from Hong Kong.
http://thecicadaproject.blogspot.com/2007/05/welcome-to-cicada-project.html
You can write a poem about it.
If your poem is Haiku, you can enter a contest, described here:
http://www.chicagocicadahaiku.com/
Or, you can just sit back and enjoy the quiet for a few more days. Most references say cicadas start singing several days after they emerge as adults.
Last night, we received a comment from Ellyn:
“At 10:00 pm we saw 2 adult cicadas flying outside our window. We live in Grayslake, IL. We have a forest in the backyard, so we expect to see thousands more cicadas in the next few weeks. “
So, my family won’t be the FIRST to find adult cicadas, but we will still keep looking. We had a long, soaking rain from Tuesday afternoon through this (Wednesday) morning. It’s pretty cool this morning, but still we are wondering how the nymphs will respond to this. Will nymphs lurking under sod and sun-baked soil finally break through to the surface? Will cicadas on the Des Plaines River floodplain finally emerge as adults?
We will check this morning and again this afternoon. We’ll let you know what we find.
The previous post listed three hypotheses that try to explain why we have found so few Periodical Cicada burrows in our yard. While testing one of the hypotheses at Chicago Portage, we came up with a fourth hypothesis. It’s based on our observations at the edge of the woods, which looks like this:
You can see a pretty clear dividing line between the mowed grassy area and the unmowed forest area. Some trees’ canopies of leaves (and underground roots) are split by the dividing line, with half of the tree over forest floor and half over mowed grass.
Here’s our observation: On the forest-floor side of the dividing line, we saw thousands of cicada burrows. On the side with the mowed grass, we saw two or three. Something about the grass, or the mowing, either limits the number of Periodical Cicada nymphs, or limits the number of burrows that reach the surface. (Maybe there are lots of nymphs under the grassy areas, but their burrows have not yet reached the surface.)
So, we came up with Hypothesis 4: Maybe we have too much mowed, grassy lawn on our block. According to this hypothesis, the current vegetation is what matters, and mowed grass somehow limits the number of cicada nymphs or limits the number of burrows that reach the surface early in the spring. This hypothesis predicts that, if we can find ungrassy and unmowed areas on our block, then we should find more burrows.
Now we have another hypothesis to test over the next few days.
We’ve been a bit disappointed this year, because our neighborhood here in south Oak Park seems so deprived of Periodical Cicada burrows and nymphs. We dug up one Periodical Cicada nymph and found a small burrow in our garden on May 2, but that’s been about it so far. Other places around Chicago have been reporting lots of burrows–so what’s wrong with our yard?
So, on Monday morning we came up with three possible explanations (which, as citizen scientists, we might call hypotheses):
1. Maybe our block is overbuilt. Hypothesis 1 puts the problem in the recent past. It says that we have few Periodical Cicadas because our block has much more space devoted to streets, sidewalks, and houses than to tree-covered lawns. By this hypothesis, there were once Periodical Cicadas here, but then we lost most of them as the area was built up starting about 100 years ago. Hypothesis 1 predicts if we can fnd a similar area in south Oak Park that was not overbuilt, we should find lots more cicada burrows there.
2. Maybe our block is former farmland. Hypothesis 2 puts the problem in the more distant past. It says that we had Periodical Cicadas here until maybe 175 years ago, but then they all died out as the area was converted to farms. Old photos of the area show fenced-in fields, and a house at the end of the block is said to be a former farm house, so there is some support for this hypothesis. Hypothesis 1 predicts that any unfarmed areas around here should have lots of cicada burrows.
3. Maybe our block is former prairie. Hypothesis 3 puts the problem in the still more distant past. It says that there were few Perioidical Cicadas here even before European farmers moved in, because our area was mostly prairie back then. Periodical Cicada nymphs suck on tree roots, but prairies don’t have many trees. Dad has seen maps that show this area as a wet prairie or marsh when the first settlers came here. Hypothesis 3 predicts that if we can find some nearby areas that have had forests growing on them for hundreds of years, we should find lots of cicada burrows there.
Now, as citizen scientists, we aren’t content with just making up explanations. We also want to test them to see if one hypothesis explains all the available evidence better than the others. Of course, all three hypotheses could be true, but we want to try to test them one at a time.
For instance, let’s start with Hypothesis 3: The Former Prairie Hypothesis. It predicts that, if we want to find lots of cicada burrows, we need to look in an area that was woods from hundreds of years ago up until today. One place where that was probably true is along the floodplain of the Des Plaines River, a few miles to the west of our block.
So, this morning on the way to a conference, Dad stopped at the floodplain forest of Chicago Portage, on Harlem Avenue just north of Interstate 55. And guess what? The forest floor was pocked full of cicada burrows! Here are some photos of the burrows, with their mud chimneys (dime shows how big they are):
When Dad turned over logs, he found lots of Periodical Cicada nymphs, as seen in this photo:
So, we tested Hypothesis 3 by going to an old forest. As Hypothesis 3 predicted, there were lots of Periodical Cicada burrows there. So far, Hypothesis 3 looks pretty good–it survived its first test.
Now we have to do more tests by going to more old forests to see what we find. We plan to look at more floodplain forests tomorrow. We also plan to look at a park in north Oak Park that is on the end of a formerly-wooded ridge. It’s not a forest, but it does have some old trees. Hypothesis 3 predicts it should have pretty many cicada burrows, too. Finally, we want to look at some areas that have been covered with prairie plants for the past few hundred years. Hypothesis 3 predicts they should have few if any cicada burrows there.
And that’s just Hypothesis 3–there are two other hypotheses as well. Looks like we have lots of trips ahead of us!
One more thing: While looking at these burrows, Dad also looked for shed Periodical Cicada skins and listened for singing cicadas–but no luck! Looks like the Chicago Portage cicadas have not started emerging as adults.
The answer seems to be, any day now! Dan at CicadaMania.com says May 14, 2004, was the “kick-off date” for cicada emergence in Illinois that year. Also, both soil probes at Spectrum Technologies have been hovering around 65 degrees for several days now (actually, more than a week at Naperville).
So, we could be seeing adults any day now—especially after a hot day like Monday (mid-80s). It’s supposed to rain on Tuesday, but it looks like a cold-front rain, not a warm-front rain, so that may not be enough to set things off. We’ll be out looking every day for the next week at least.
A few days ago, Roy Troutman provided this advice in a comment. (The scientific name for Periodical Cicadas is Magicicada–a really cool name!) ”Magicicada nymphs tend to start emerging in sunny areas first & then migrate to more densly shaded areas over a week & 1/2 period. Soil temperatures were about 5 degrees cooler under dense shade as opposed to areas that had full sun all day. I experienced this phenomena in my backyard in 2004.”
So, we will be hunting for adults in open areas with scattered large trees and on the south edges of wooded areas. We will also look on shallow hills that face south, which get more sun and warm up faster than flat places or north-facing slopes.
As detailed in the previous post, we expect to find signs of adult cicadas before catching the first live adults.
We’re wondering if the current cooler temperatures in northern Illinois will set cicadas back a few days? But once it warms up, we wish good cicada hunting to all!
We’ve been remembering our experiences looking for the first Annual Cicadas every year, and then applying them to our search for the earliest Periodical Cicadas. We’re guessing that a few cicadas will emerge early, evenings before the big night when huge numbers of cicadas emerge at once.
The first evidence we find may be a few shed skins of nymphs, on trees trunks, dried weeds, or other upright surfaces. Of course, the first emergers may not live for long–they will probably be gobbled up by birds. So we can also search the ground for cicada wings that smaller birds break off and leave behind. The wings are beautiful, a bit more than an inch long, and look like leaded glass with orange and reddish trim. If we are really lucky, we may see cicada-hunting birds searching, catching, and fighting over what they find. We may also hear adult cicadas before we see the live ones, although we’d expect the songs a day or two after the first adults first emerge.
By the way, while looking for shed skins of Periodical Cicadas, you may also find old shed skins of Annual Cicadas left over from last summer. Here’s a photo that compares the two. The relatively longer and narrower Periodical Cicadas are on the left, and the Annual Cicadas are on the right.
Of course, if your kids feel apprehensive about what’s coming, you can use the cicadas slow start to get yourselves desensitized to what’s coming. You can search for the first few skins and wings, look at them from a distance and then closer, and maybe work up the nerve to touch them–with one small finger first. Then, when faced by your first live adults, they might not seem so strange and frightening.
Here’s are two OLD photos of shed skins and wings collected in 2003, when some Periodical Cicadas energed four years early in the Chicago area:
You can read more about that really early emergence here: http://www.saltthesandbox.org/cicada_hunt/Periodical2003.htm
You can also read about our annual hunt for the first Annual Cicadas on this page:
http://saltthesandbox.org/cicada_hunt/DatesFound.htm
This morning, the Chicago Tribune published an article, “Cicada Nymphs Can Wait No Longer,” about folks finding Periodical Cicada nymphs under rocks and logs in the Chicago suburbs: http://www.chicagotribune.com/news/local/chi-0705070741may08,1,1785301.story?coll=chi-news-hed
Also, be sure to check these additional photos starting here:
http://www.chicagotribune.com/news/local/chi-070507early-photogallery,1,2664332.photogallery?coll=chi-news-hed&index=1
Although the article says, “A few cicadas are making an early break from the subterranean world,” they did NOT show photos of anything but nymphs. Also, it seems that the cicada finders had to do some work to see them (although they just turned stuff over, they did not have to dig). In other words, NO adult cicadas–yet! We still have a chance to be the first to find cicadas with wings….
The article also discusses predictions of when adults will appear, including Gene Kritsky’s formula that predicts May 22 as the date. His formula is reported to have worked quite well for Ohio in 2004. However, we’re wondering if we’ll see variations in emergence across the region, given that soil temperatures vary from place to place. At Spectrum Technologies’ Cicada Watch 2007 website, temperatures have been up to 6 degrees apart for their two soil-probe sites:
http://www.specmeters.com/cicada_2007/index.html
That said, the overall spin of the article was pretty postive. These people’s cicada curiosity seems to have overcome their dislike and fear.
Many articles and blog posts about Periodical Cicadas emphasize adults’ dislike, disgust, and even fear of these insects. Bloggers sometimes trace their feelings to childhood experiences—stepping on cicadas, bumping into flying cicadas, or feeling a cicada dropped down their shirt. This gets me wondering—what can we do for today’s kids to help them enjoy these amazing bugs? (My own boys have already promised not to force cicadas on their bug-phobic friends, but there must be something more.)
Before the big Cicada Emergence of 2004, a mother and grandmother in Washington, DC, felt similar concerns. They wrote and illustrated a book—Cecily Cicada—especially for preschoolers who needed help with that year’s cicadas. Cecily Cicada tells her life story in terms young kids relate to—by giving her human feelings. Wouldn’t seventeen years underground get boring? Then let’s imagine how Cecily might pass the time. How does it feel to shed your skin and grow wings? Cecily was surprised—she didn’t know what was coming. What do cicada songs sound like to Cecily? Of course, they’re so beautiful that she fell in love with the singer!
Reading Amazon.com reviews, it’s clear that Cecily Cicada helped lots of kids in 2004—it’s a parent-tested and child-approved way to subvert cicada-phobia. I asked my neighbor to try the book with her children, and she said it communicated lots of facts about cicadas along with all the fantasy. However, it might not be as effective with children older than 1st grade.
If there’s a child in your life who might need help preparing for this year’s Periodical Cicadas, you can visit the following Web page for information about purchasing the book: http://www.cecilycicadabook.com/
You can also buy copies at:
Magic Tree Bookstore in Oak Park, Illinois.
The Morton Arboretum store in Lisle, Illinois. (Also check out their exhibits and programs about Periodical Cicadas)
The Grove Store at The Grove Interpretive Center in Glenview, Illinois. (Also check out their exhibit about Periodical Cicadas.)
We’ve been hearing more reports of both Periodical Cicada nymphs and their burrows from folks in nearby towns. (Go here to read some of them: http://www.cicadamania.com/message-board/hello-world/ )
We were getting jealous, so we went digging in our front garden again on Wednesday afternoon. This time Ethan found a REAL Periodical Cicada nymph. We could tell it was a Periodical Cicada because it was relatively longer and narrower than Annual Cicada nymphs, and it had dark red eyes. We also found an Annual Cicada nymph, so we took a photo of them together (below). The Periodical Cicada nymph is on the left, and the Annual Cicada nymph is on the right. (There is also a dime in the photo, so you can tell how big they are.)
Both nymphs will have darker bodies when they finally emerge. The Annual Cicada nymph also will grow larger, and it’s eyes will turn dark brown.
We also found a bit of broken mud chimney from a Periodical Cicada burrow.
A photographer from our local Oak Leaves newspaper was there taking pictures as we dug. She captured this image seconds after Ethan found the first nymph, and it was published on the front page:
You can read the whole story here :
http://www.pioneerlocal.com/oakpark/news/376249,OP-Cicadas-050907-S1.article
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