Looking around the woods, we found more burrows among the dead
leaves.
Most of these burrows had rounded mud caps covering the entrance.
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 more like rounded caps
than
chimneys or turrets. Our mud caps had no openings at the top. So,
we
did NOT find an exact match for any periodical cicada burrow we’ve seen
on the Web. But then, conditions on April 8 were pretty different from
when
the Web photos were taken. We found the at least five or six weeks
before
the cicada emergence is expected around here. Also, it has been cold
for
the last several days, even below freezing in the mornings.
If these really are periodical cicada burrows, maybe the mud
caps are a way
to protect cicadas in the burrows from the cold, or from rain, or from
predators
while the nymphs wait until emergence time.
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.
So, the hunt continues....
MORE BURROWS
(cicada or not?)
Saturday, April 14, 2007
On Saturday, April 14, the boys and I were bird watching 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 burrows
we found on
Easter Sunday (smaller than a dime). However, these burrows did not
have
mud caps (like the Easter burrows) or mud chimneys (like many periodical
cicada burrows have). Here's what they looked like:
As you can see above, a few burrows seemed to
have mud linings that were
a slightly different texture than the surrounding soil (on the left), and a few
had
just a bit of mud built up on their edges (on the right). Below, you can
see a
burrow with crumbly soil at the edges (center of photo), as if something
had
tried to dig down into it from the surface.
So, were these periodical cicada burrows?
Crayfish? Something else? We’re not
sure. They don't fit the classic descriptions of periodical cicada
burrows. I guess
we will check this area again in a week or two and see if the burrows have
changed.
By the way, we also flushed a woodcock in this thicket.
Woodcocks are birds with
long beaks, which they poke into the ground to find worms and other soil animals
to
eat. Go
here to learn more about the American Woodcock. This got us wondering.
Maybe the woodcock had been sticking its bill down these holes, trying to fish
out
whatever was in there.
So, the hunt continues.... And we will
be watching for hungry woodcocks as well as
cicada nymphs.
MORE ANNUAL CICADA NYMPHS
Sunday, April 29, 2007
Over the previous week or so, we had 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 are photos 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 could 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 saw the photo on
our blog and used the comment section
to correct our preliminary identification. He said it was 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 (which should be turning red by this point in their lives).
We vowed to dig again in a few days and see if we can 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 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.
So, the hunt continues....
TAKING THE
TEMPERATURE OF THE SOIL
Sunday, April 29, 2007
Lots of websites and newpaper articles state that Periodical
Cicada nymphs
will emerge, all at about the same time, when their body temperatures
reach
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 in 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 suggested
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.
So, the hunt continues.... And we will
be watching soil temperature so we know
when to intensify our search for emerging cicadas.
WE FINALLY FOUND A
PERIODICAL CICADA NYMPH
Wednesday, May 2, 2007
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 really are.)
Both nymphs will have darker bodies when they finally emerge.
The Annual Cicada nymph also will grow larger, and its 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
So, the hunt continues.... But now we
are looking for the first adult cicada!
WHY HAVE WE FOUND SO FEW NYMPHS
AND BURROWS IN OUR YARD?
Monday and Tuesday, May 14-15, 2007
This story is still being written. The first draft is on our
CicadaBlog.
Please go to our
CicadaBlog to read this story
THERE IS SO MUCH HAPPENING AS OF LATE
MAY THAT WE HAVE BEEN PUTTING ALL OUR LATEST FINDS ON THE CICADA BLOG
Please go to our
CicadaBlog to see what we've been up to!
