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May 30, 2024 53 mins

In this episode of Stuff to Blow Your Mind, Rob and Joe explore the world of the periodical cicada, from their curious lifecycle to their mythological and culinary roles in human cultures. 

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Speaker 1 (00:03):
Welcome to Stuff to Blow Your Mind, production of iHeartRadio.

Speaker 2 (00:12):
Hey you welcome to Stuff to Blow your Mind. My
name is Robert Lamb.

Speaker 3 (00:16):
And I am Joe McCormick. And hey, folks, if I
sound a little bit unusual today, it is because I
am recording with a bit of a cold, yet another
respiratory infection that I believe I caught from my toddler.
And this actually, in a strange kind of indirect way,
does connect to what we're talking about today, because just recently,

(00:38):
it was over this past weekend, I saw my toddler.
She was running around in our living room, and I
saw her stop and reach down to pick something up
off the floor. And Rob you might remember, you know
this move from your son's earlier days. You were like,
the child reaches down to grab something off the floor,

(00:59):
and you have to get there first because you don't
know what the thing is and you want to prevent
the possible ingestion of the mystery substance. Sometimes it goes
straight into.

Speaker 2 (01:08):
The mouth, exactly. Yeah, you need to know what has
been picked up. It could be harmless, it could be,
you know, one of the various dreaded items and so forth.

Speaker 3 (01:18):
Right, so in this case, I was like, what is that?
But I got to it first, and I picked it
up and realized it was a large, transparent wing, an
insect wing. In fact, it was a wing belonging to
a cicada, just sitting there by itself on the floor.
How it got in the house, I do not know.

(01:38):
I guess we may have tracked it in on our
shoes from outside. But it was kind of this evocative
little clue, this mystery, like where was the rest of
the insect? No idea, but this random arthropod body part
in our house was like just a little taste of
the great cicada biomass, both alive and dead that there

(02:00):
was outside in the surrounding foliage.

Speaker 2 (02:04):
And maybe almost a literal taste. But you got there first,
like you said.

Speaker 3 (02:08):
Yeah, yeah, don't I don't know where insect body parts
factor in when it comes to like full mites and
transmitting germs. No, I have not read into that. But
fortunately it did not go in any mouths, but we
got sick.

Speaker 2 (02:20):
Anyway, this will be discussing. You know, circadas are are
are good eats, so I don't know if it would
have been that bad. And also going back to our
multi part episode on dust It's like, sorry, there are
insect parts in the house, either in whole, partial or
dustified particleized formats. So it's just part of part of

(02:42):
our living environments. So yeah, cicadas are a regular annual
cicadas anyway, our regular feature of summer down here in Atlanta.
They're not quite out in forced just yet. But over
the weekend I ventured up into Tennessee and got to
experience the current and explosion of periodical cicadas uh and

(03:03):
it was pretty awesome there. I was. I hadn't been
around them in a bit, so I was a bit
surprised because they were smaller than I expected them to be,
as the periodical cicadas typically are, I'm to understand, But
they were still wonderful to observe, to listen to, and
in general, that swelling of the cicada song is just
such a regular feature of the summer, especially in the

(03:26):
most oppressively hot months, you know, those dog days of summer.
So this would you know, we'd definitely be talking about
the uh, the the annual cicadas in this scenario. To me,
it's always felt like that is the sound of humid
southern heat, a heat that often feels like it hits
you in waves anyway, just as that cicada song hits

(03:48):
you in waves sonically.

Speaker 3 (03:49):
Rob, did you mention the dog days of summer, because
there is a specific cicada species known as the dog
day cicada?

Speaker 2 (03:56):
Exactly, yes, And that's the that's the connection there that
they or so the late in the summer during you know,
the off like the sweatiest, hottest time, the time when
you go outside and you feel like you've landed on
mercury or something.

Speaker 3 (04:08):
H also known as the heat bug.

Speaker 2 (04:12):
They do like it hot. And that's another feature too.
It's like, you know, early in the morning you might
not hear them yet, and then you know, very late
in the afternoon slash evening when you dare venture out again,
their song might be dying off for the night and
so forth. So that's one aspect of just sort of
life with cicadas. But the shed exoskeleton of the cicada

(04:34):
has also always enthralled me as well. You know, this
monstrous little form that's left behind a kind of monster
gym that you can just pick up and you can
pocket pocket it, you can clip it onto the end
of your finger or a stick, or maybe like an
old gi Joe man's head or something. Even before I
saw nausicaa of the Valley of the Winds. I love

(04:58):
these things, and if I find one to these days,
to this day, I will bring it up and give
it a more prominent place on the front porch. You know,
like I need to show it to my son, even
if he's he's still interested in this sort of thing,
but I still have to show it to him. I
still have to sort of like put it on display
for myself. There's just something special about finding them.

Speaker 3 (05:18):
Yeah, I agree. There there was a time a few
years back when my sister in law was like collecting
the the molted cicada exoskeletons, which have been named by
the way they're They're called the exsuvia or the exuvier.
These these exoskeletons after the the cicada molts and leave
leaves it behind. Yeah, you can find them all over

(05:40):
the place, and they are a lot of fun to collect. Yeah.

Speaker 2 (05:44):
Yeah, they're already like pre dried out, ready to go.
There's nothing really gross about them. I mean, you know,
respect to anyone who who is grossed up by cicadas
will get into it. But well also probably probably dispel
some of the reasons, the logical reasons anyway you might
be opposed to them. But yeah, these these these are
wonderful because they're if you if you haven't ever encountered one,
and I feel like a lot most of you maybe have,

(06:07):
they are like full form, like there's a slit down
the back where the adults cicada has emerged, but otherwise
it's like this perfect little exoskeleton shell. It's not like
a snake skin, which you know, doesn't have like the
head of the snake on it or anything. You know,
it's it's it's not in any way like you can
you can see the full form really the exoskeleton form

(06:29):
of the nymph form of the cicada.

Speaker 3 (06:33):
That's right, because Rob correct me if I'm wrong. But
I think most of the exuvia that you will find
these shells are the final form of the of the
young cicada, the nymph form when it comes up out
of the ground, crawls up a tree, and then it
molts and emerges in its adult form.

Speaker 2 (06:50):
Yeah, I saw one rite up even that kind of
stressed the idea that essentially what we have emerging is
the adult cicada, the adult winged cicada, but it is
still wearing the exoskeleton, hasn't like pushed off that final
molt just yet, which is kind of an interesting and
slightly grizzly and suitably alien idea to.

Speaker 3 (07:14):
Give adult humans ready to vote and buy beer were
like coming out of the house still wearing their child
skin and they had to like burst out of that.

Speaker 2 (07:22):
Yeah, that sort of thing. So, yeah, I figured a
lot of us have cicadas on the brain, either via
direct experience or via a lot of media coverage, So
I figured let's actually dive into them and do some
episodes on them. And I want to stress that there
will be a two week break between this Cicada episode
and the next one due to scheduling here. We're going

(07:43):
to do a little small summer break during which we'll
have some reruns, but we'll also have some new omnibus
episodes of Monster Fact episodes and Anamalia stipendium, so there'll
be some new content sprinkled in there. But basically there's
gonna be a little break and then there will be
more Cicada content, which I think is kind of fitting

(08:04):
for the cicada, because we're talking about a creature that
does go on extended breaks at times before it re emerges, like.

Speaker 3 (08:12):
The god Tamuz disappears into the underworld and reappears again
later exactly. All right, Well, I'm going to start off
with some basics about cicadas as a family of insects
and a bit about their taxonomic context. So, cicadas are
a family of insects within the order Hemiptera. The order Hymiptera,

(08:32):
meaning half winged, contains insects such as plant hoppers and leafhoppers,
assassin bugs, spittlebugs, moss bugs, bedbugs, and aphids. The Hymiptera
are sometimes called true bugs, which I like because it
does imply that there are false bugs. And this was
a bit of a surprise to me because I always

(08:54):
thought of bug. The word bug as just an informal,
non scientific term that it had no criteria, and it
could be used to refer to basically any arthropod smaller
than a crab, any creepy crawley thing. In common usage,
it is that, but bug also has a specific scientific
meaning to entomologists referring to the Hymiptera insects, so as

(09:18):
an example of the many false bugs. The lady bug
is not actually a hymipterin it's a beetle, so it
is technically not a bug. The same is true of
many insects that have the word bug in their name.
June bugs are also not true bugs. They are beetles.
So as a side note, this got me kind of
interested in the etymology of the word bug. Where did

(09:39):
this confusing term come from? Well, I found a few
different sources on this. For one thing, Miriam Webster had
an interesting post on this etymological development. So the English
term bug did not always refer to an insect at all.
It did not necessarily refer to a creepy crawley animal.
In Middle English, the word bugs spelled with two g's

(10:01):
and an e at the end. Love that bug referred
to a monster like a hobgoblin, or to a scarecrow.
The scarecrow usage appears in John Wickliffe's thirteen eighty two
English translation of a deuterocanonical biblical text, a text that's
not used in all denominations versions of the Bible, but

(10:23):
it's used in some Christian traditions. It's called the Book
of Baruk and Wickliff's translation goes as a bug either
a man of ragis in a place where gordis wexen
keepeth no thing, so bin her goddess of tree. And
in modern English that would read something like as a
bug or a man of rags in a place where
gourds grow guards nothing, So are there gods of wood?

(10:47):
So this is a verse I think comparing idols used
in religious worship to a scarecrow in a garden, I
think the implication being that they are like both an illusion.
A common theme in Judaism in Christianity is against the
religious use of.

Speaker 2 (10:59):
Idea fascinating all right, I had no idea.

Speaker 3 (11:02):
So bug is a scarecrow there in the fourteenth century
bug is a scarecrow, but by the time of Shakespeare
it seems to have lost this meaning and refers to
a type of monster or spirit or specter. So consider
the line in Hamlet. Hamlet is he's complaining, he's lamenting,
and he says, oh, such bugs and goblins in my life.

(11:24):
That's an Act five, scene two. He's talking to Horatio.
And you can also see this use of bug as
monster in the word bug bear, which is attested since
the fifteen eighties, meaning a monster or generally a creature
or simply a notion which causes terror. I think a
bug bear is supposed to imply some kind of demon
bear or monstrous bear which frightens children.

Speaker 2 (11:47):
Yeah, and I think that usage still kind of remains.
And then of course in the world of dungeons and dragons,
you have the bug bear as an actual monster and
I think sometimes playable species. So the bug bear lives on.

Speaker 3 (12:00):
So yeah, bug as monster or bug as kind of
a devil. You know, it's a like a devil version
of a bear. So there seems to be a common
root of bog or bug observable in Scottish and Welsh
terms referring to terrors, devils, inspectors. You can think of
later derived terms like bogie, which seems to be it's

(12:21):
like a later word that has the same root, I think.
And according to the online Etymological Dictionary, some linguists have
guessed that there is a root in terms used for
a male goat. It does so like bug here as
monster shares a root with buck. So if you go
all the way back, this may come from ideas of

(12:44):
some sort of evil spectral he goat but that's far
from certain. So, according to the Merriam Webster etymology, by
the late fifteen hundreds the term referred to earthly insects
in some usages, particularly pest insects, and then by the
late seventeen hundred's the emerging Linaean classification system scientific terms

(13:05):
for taxonomizing and referring to animals that assigned the term
bug to the order Hmiptera, though of course it is
still commonly used to refer generically to little creeping things.
But how did this transition from like monster or scarecrow
to insects happen? I was reading another article, this one

(13:26):
for the California Alumni Association, which included interviews with a
Berkeley linguist named Jeffrey Nunberg, and this sort of made
the point that bug, originally having the association of a monster,
came to refer to insects because of their resemblance to monsters,
particularly bedbugs, which were probably the first insects to be

(13:48):
called bugs. Because they suck our blood in the night.
There is something kind of monstrous and awful about that.
And this type of association continues for many other uses
of English today, a lot of them have to do
with like irritation, disgust, and infestation, a computer bug, a
bugged phone line, a flu bug, bugging someone as in

(14:12):
bothering them. A lot of them have this kind of
conceptual association with like irritation or problems.

Speaker 2 (14:20):
Interesting.

Speaker 3 (14:21):
Interesting, So that was all sidebar, But I thought that
was interesting. I never knew any of that before. So
to come back to actual insects, Cicadas belong to the
order of true bugs, the Hymiptera, of which there are
probably about eighty thousand or more species. The most distinctive
body features shared by the species of Hymiptera are the

(14:43):
piercing and sucking mouth parts. So these insects have what
could be referred to as a sucking beak, technically known
as a rostrum. So if you want to picture it,
it is like a hinged, segmented, hollow needle. It is
used to pierce the outer layer of the food source.

(15:03):
And this could be a number of different things. It
could be the outside of a plant or the root
of a plant, could be the exoskeleton of an insect.
And then they're the needle pierces. And then there is
sort of a pumping organ operated by muscles that allows
the bug to suck up the liquid inside that substrate
for nutrition. Hymipterins typically inject an external digestive enzyme into

(15:26):
whatever they are eating to help break down starches and
proteins inside the food substrate, and then they suck that
food juice up through the hollow core of the rostrum. Now,
the hymiptera include both herbivores and carnivores, so again, this
food that they're sucking up through the sucking beak could
be a plant based liquid like tree sap or like

(15:49):
the xylum in plant roots in the case of a cicada,
Or it could be an animal based liquid like your
blood in the case of a bed bug, or like
the runny liquefied inside of a caterpillar in the case
of an assassin bug. In terms of other body features, many,
but not all, hymiptera, according to their name, which again
means half wing, have wings with two distinct parts, a

(16:12):
leathery or thickened part near the base and a thin
membrane toward the tip. But not all hymiptera are like this.
A cicadas are an exception. If you look at a
cicada wing like the one I found on my floor
the other day. They tend to have fully membranous, transparent
wings with just these vein sort of structural veins running
through them. Cicadas in particular are a superfamily of insects

(16:37):
within Hymiptera. The suborder they belong to is aucinorinka. There
are more than three thousand species of cicadas worldwide, found
in lots of different environments in the tropics and intemperate environments.
They range somewhat in size. The smallest cicadas are less
than an inch long as adults. The largest species, the
impress cicada, has a body length of about seven cinemi

(17:00):
in a wingspan of up to twenty centimeters and Cicadas
have the standard three part insect body division of head, thorax,
and abdomen. On the head, cicadas generally have five eyes.
They've got two huge, bulbous compound eyes on either side,
and then three smaller simple eyes known as o'celli, arranged

(17:20):
in a kind of triangle or pyramid pattern in the
middle of the head on the top.

Speaker 2 (17:24):
I've always thought they were quite cute they have I
think they have kind of like cute heads slashed faces
if you will. Yeah, and the size is notable as well,
because if you are in an area where there are
lots of cicadas, they're going around doing their thing. They're
kind of oblivious to your thing, so they may bop
into you at various times and or land on your shirt.

(17:46):
And with the larger, I guess mainly the annual cicadas,
it's it can be like a like a large ping
pong ball hitting you, you know, it can be that
level of impact, and then they stick on there for
a little bit. Maybe they crawl into your shirt. They've
been known to freak out the occasional child or bug
adverse person.

Speaker 3 (18:05):
Yeah, and some cicadas in particular are kind of seem
kind of brazen, seem less threatened by large animals like
us than some other insects would be. The average adult cicada,
they've got these relatively short antennae, kind of like little
bristles on the head, and a thick, stout body with
folded wings usually reaching back beyond the end of the abdomen. Now,

(18:39):
I wanted to do a brief thing here on cicada singing,
because of course, cicadas are famous for the music they make.
You might call it music, you might call it noise.
The sounds they make, and in fact, cicadas are the
loudest family of insects on Earth. I was reading about
a study by Sanborn in Phillips in nineteen ninety five

(19:00):
that found that the average sound pressure of the mating
call of thirty different species of North American cicada was
between eighty and one hundred and six decibels. That is
incredibly loud for a sound made by insects. These noises
are often compared to the sounds made by powerful machines.

(19:20):
For example, I just looked up some averages of the
decibels produced by noisy things. Apparently, a riding lawnmower, if
you are sitting on the mower so like at that distance,
is about ninety four to ninety five decibels for the rider.
A motorcycle is about one hundred and five decibels. A
chainsaw in your hands might be more like one hundred

(19:43):
and fifteen. So, especially for their size, cicadas are almost
unbelievably loud animals.

Speaker 2 (19:50):
Yeah, I can pretty much sound like there are leaf
blowers or weed whackers running in like all adjacent yards
to the property on. They're just incredibly loud. But it's
even louder than that, especially if you are in an
environment surrounded by like a lot of trees forests, because
it's like the forest itself feels like it's alive. With

(20:14):
this buzzing again, it can feel like it's the sound
the world is making, as opposed to creatures in the world.

Speaker 3 (20:21):
Yeah, cicadas can produce sounds that come pretty close to
the pain threshold for human hearing. Now, because cicadas make
these chirping and worrying sounds, you might be tempted to
lump cicadas in with other noise producing insects like crickets
and assume that they all make their sounds the same way.

(20:41):
But cicadas actually have a unique mechanism. Locusts and grasshoppers
usually the males chirp by rubbing their hind legs against
their fore wings. Male crickets chirped by rubbing the edges
of their wings together in this sort of like file
and scraper system like a comb a stick. And these
rubbing based systems are called stridulation, you know, causing friction,

(21:06):
a loud type of rubbing together. Cicadas do not use
stridulation instead. Most male cicadas have a dedicated pair of
sound producing organs called the timbals, which are ribbed corrugated
kitenous membranes on either side of the body, near the
base of the abdomen, sort of where the abdomen connects

(21:28):
to the thorax rob I've attached some pictures for you
to look at here. One is a close up of
a cicada showing the timbal is usually tucked under the wings,
so you might not see it that easily, but if
you move the wing to the side, you can see
this interesting little patch in the in the exoskeleton that
I don't know exactly what I would compare to, though

(21:49):
it does have a clear sort of corrugated appearance. It
looks ribbed.

Speaker 2 (21:53):
It's like they're in a jug band and they play
like the washboard, right, but the washboard is part of
their anatomy.

Speaker 3 (22:01):
They have solved it, yes, except in the washboard you
play by rubbing a stick on it, so that would
be more like a form of stridulation. That's not how
the timble works. So it's like if the washboard worked
instead by collapsing in on itself and then snapping back
into place.

Speaker 2 (22:19):
It's like, I want to compare it to some there's
some sort of like a fidget toy of some sort
that I'm half imagining here.

Speaker 3 (22:27):
That you're thinking of the whirly tube, the like that
plastic tube that you can make sounds into and you
like snap the ribs in and pull them out.

Speaker 2 (22:35):
Yeah, though I guess there's probably that probably produces it
sound in part by air as well. I haven't messed
around with one of those in a bit, but maybe
akin to that, if we're sort of tragulating things like
a little bit of washboard, a little bit of that toy,
maybe something else thrown in there as well.

Speaker 3 (22:51):
Yeah. So I actually got curious about the mechanics of
how the timble makes the sound because I couldn't based
on what I was reading, I couldn't quite picture it.
And I finally found a source that got into the
details here. So this was in a press release tied
to a twenty thirteen acoustics conference presentation by a team
from the Naval Undersea Warfare Center in Newport, Rhode Island,

(23:12):
and the press release was published by the Acoustical Society
of America. Apparently, these Naval researchers were interested in studying
cicadas because cicadas are able to generate an extremely loud
sound with a very small body using relatively little energy,
and they thought this type of technology could be useful
for underwater communications, rescue operations, beacons, ship to ship communication,

(23:36):
remote sensing, that kind of thing. The article quotes a
researcher named Dirk Hughes who was part of this team
at the NUWC, and also summarizes their conference presentation by saying, quote,
the explanation in brief is that a buckling rib is
arrested in its rapid motion by impact with the part
of the cicada's anatomy called a timble, which functions somewhat

(24:00):
as a gong being hit by a hammer. It is
set into vibration at nearly a single frequency, and the
vibration rapidly dies out. Hughes tries to make the analogy
to human bodies and says, I don't know if this
really works all that well, but he's trying. Okay, So

(24:20):
Hughes says, you should imagine like using muscles inside your
chest to pull your ribs in until they buckle inward,
collapsing into your body, and then you relax the muscles
and release the ribs and they snap back into place
and they hit this gong's timble. So the collapsing and
snapping back process makes this clicking sound with the timble.

(24:43):
And then if you do this like three hundred or
four hundred times a second, you have the kind of
buzz or whirr the cicadas do. And then you can
change it to alter frequency and rhythm patterns and so forth.

Speaker 2 (24:57):
It's slightly horrifying, but I think I do get what
he's going for here. That does make more sense.

Speaker 3 (25:03):
So I was reading more about the function of cicada
sounds in a book called Courtship and Mate Finding an
Insects A Comparative Approach by Raymond J. C. Cannon, And
according to canon, adult male cicadas emit sounds for a
variety of different reasons. There are very importantly mate attraction calls.
These are produced by males to attract females across a

(25:25):
long distance and help males and females find each other. Apparently,
the females respond by also making a sound, not with timbles,
but in some cases by snapping their wings together, and
this sound in turn attracts the males. There are courtship songs.
These are somewhat different, and they occur once a male
and female have found each other. It sort of further

(25:47):
cements a mating relationship. It's the wooing song. If the
female likes what she hears, the cicadas will mate. There
are also interestingly congregational songs. These occur when cicadas gather
in large groups, and maybe we can talk more about
the function of these later. But then there are also
disturbance sounds. These happen if a cicada is caught or

(26:09):
feels threatened, it'll make a distress sound. Now, the timbles
are very common, but Canon also mentions some cicadas have
a different system. Canon writes quote, some cicadas communicate using
a different type of sound production called crepitation. Sound pulses
in these species are produced by slapping the wings together
over the body or slapping the wings against the body surface.

(26:32):
Thus there are both crepitating and timbling cicada species. But
as I said, a very important function of the sounds
produced by the cicada is for mating. And mating of course,
kicks off the life cycle of the cicada. Which is
a fascinating subject in itself that I guess we will
need to get into, but maybe in the context of

(26:54):
talking about the difference between annual and periodical cicadas.

Speaker 2 (26:58):
That's right now. As we get into this, I want
to turn. I want to point out that one of
my sources here is a book by one of our
past guests, Gene Kritsky. We chatted with him a while
bag this was years ago about his excellent book The
Tears of ray Bee Keeping in Ancient Egypt. He's an
excellent authority on that topic, but he has also authored

(27:20):
numerous books about the cicada, and you even see him
popping up in the media to chat about them. A
couple of weeks ago, on John Oliver's Last Week Tonight program,
they had a supercut of people on TV like slamming cicadas,
like talking smack about cicadas, and there was actually a
clip of Gene in there saying that they stink. Yeah,

(27:42):
it's it's funny. It's worth looking up. It's it's a
very funny segment. But of course, knowing who Gene Kritsky is,
knowing that like few people are going to be as
big a fan of cicadas as this guy that kind
of made it even funnier, you know. But anyway, so
I'm gona refer to to Kritsky a fair bit. But

(28:02):
one thing I want to stress beforehand, this is also
citing his work, We need to stress that cicadas are
not locusts, despite the fact that they were commonly called
locus for a very long time, and this mistake continues
to linger in the popular mindset and even in the
media to a certain extent, not in terms of like
the actual calling them locus, but also but thinking about

(28:25):
them in terms of locusts.

Speaker 3 (28:27):
M yeah, so like, oh, when the when the brood
of cicadas emerged, they're they're like locusts, a plague of
locusts descending upon the land right now.

Speaker 2 (28:36):
Not to say the cicadas cannot be destructive to a
certain degree. I mean, they can litter their bodies everywhere,
and and animals will be hard pressed to keep up
with eating them all. So that can kind of make
a mess.

Speaker 3 (28:48):
And then the reasons we can talk about they can
damage some plants.

Speaker 2 (28:51):
That's true. That's the other big thing is that via
the way and the place that they lay their eggs,
there can be some plant damage, but these not like
the locusts that you think of in terms of like
big biblical plagues of locus descending on crops. However, the
thing is, as Kritsky points out, Europeans in the Americas

(29:13):
called them flies. In the seventeenth century, they called cicadas flies,
and then they called them locus during the eighteenth century,
again despite the fact that they certainly are not locus.
Locus are grasshoppers, so they're in a different order altogether.
That's orthoptera locus. As with accounts of biblical plagues, you know,

(29:34):
we're talking about creatures that feast on leafy matter and
thus crops. Cicadas consume plant sap. Most of that plant
sap consumption is taking place underground, as we'll be discussing,
and there was also there are also these long standing
superstitions that cicadas caused illness, which on one hand you
could probably connect to European biblical ideas about plagues of

(29:55):
locusts and so far forth. But native peoples of America
is apparently all so believed in this to some extent
as well. We may come back to this later on.
At present, i'm not sure how much of this, you know,
you're just getting into the idea that, especially in North
America with periodical cicadas, there may be just some sort
of idea of potential portents in the way things seem

(30:20):
to work out in the natural world, like something that
is occurring, you know, ever so many years. Well, you
can imagine how one might take special notice of that,
and maybe that does end up matching up in a
non meaningful way with events that have occurred in a
given people or in a given region environmentally. He also

(30:43):
points out that there was also an early colonial Early
American tradition in which you could predict wars or peace
based on whether you could see a W or a
P spelled out on the wings of the cicada, and
Risky points out that their wing veins only ever make
a W. They can't really make a pee unless you again,

(31:06):
unless you really really want to see a pe there,
I guess, and that in general it was a safe
prophetic bat during this time period to see the W
as opposed to the P. Getting back though, to the
cicada itself, let's start with the basics of the life cycle.
Any sort of cicada you're looking at has three stages
egg nymph and an adult an adult female lays an egg,

(31:31):
as we teased out earlier, in plant tissue, usually woody
plant tissue. This is going to be essentially injected via
its ovipositor.

Speaker 3 (31:41):
We should stop for a second and dwell on the
organ that the female uses to lay these eggs. So
it is a fairly remarkable mechanism. As you said, Rob,
it's this external appendage called an ovipositor, and this ovipositor
organ is essentially a knife that lays eggs. It's like
a hollow, sharp, rigid spike knife thing. It contains a

(32:06):
significant amount of metal in the tissues, metal content. And
using this metal studded ovipositor, the female cicada slices and
gouges these deep slits into the wood of a tree,
usually a softer part of the tree, like a new
branch with the green wood, and then cuts these gouges
in there and lays clutches of eggs inside the slits.

Speaker 2 (32:29):
That's right, and this is why you know technically they
the cicadas can damage plants and so forth, So this
is how the eggs are laid. The eggs then of
course end up hatching, and this will take a matter
of weeks, and what emerges is a wingless nymph which
burrows down into the ground to suck the juices from

(32:51):
the roots of perennial plants. So they're little subterranean plant vampires.
And while they feed, they grow and they mold and
eventually more on this. In a second, they emerge from
the ground and undergo one last molt into wing it
adult form. This will be their final form, and they
use it to complete their life cycle in just a

(33:12):
few weeks or less of mating and egg laying.

Speaker 3 (33:16):
Now there are a lot of interesting scientific questions about
what happens while the cicadas are in their their various
nymph forms. The different periods between the moltings are referred
to as in stars, the different nymph in stars. Underground,
they're doing something down there. They're feeding on the plant roots.
They're sucking xylum up from the plant roots with their

(33:37):
little rostrums. They're you know, sucking beaks, and they're growing.
But there's a lot of there are a lot of
scientific questions remaining about that part of the cicada's life
cycle because it's not that easy to study.

Speaker 2 (33:48):
Yeah, because when they're out and about in their full
adult adult forms. You are at great pains to ignore them,
like good luck. Just eventually you just kind of get
used to it, I guess, but you cannot deny that
they are there. But when they're underground, it's kind of
out of side, out of mind. You may turn one
up on digging in the yard, I've done that before,
but otherwise we simply live in different worlds. They live below,

(34:12):
we live above. They're quietly drinking that plant sap and
only ever having to contend with various subterranean threats such
as I've read in ants in some cases can go
after them, moles may go after them, some other subterranean
insectivore or surface world diggers. I've also read, you know

(34:33):
certainly about bears or humans digging them up for food.
More on that last point later on, But yeah, for
the most part, they're down there that they're undergoing additional
moltings as they grow older. They're also going to go
deeper and find different roots to feed upon. But how
long do they stay underground and when do they emerge?

(34:53):
This is where we see the primary difference between the
very species of annual cicadas and periodical so annual. Cicadas
can be found around the world. As the name suggests,
they emerge every year. Now, this doesn't mean they only
spend a year underground. They have Typically this is going
to vary from species species, but we're talking about two

(35:13):
to five years underground. But the short duration and the
timing of their nymph stages just means that every year
there's going to be an emergence. Think of it like this.
There are a number of different production companies out there
making superhero movies, and they might not all put out
a superhero movie every year, but enough of them or
in some state of production that it's a pretty safe

(35:36):
guess that at least one superhero movie is going to
come out every year, And if your life cycle depends
on that, then then you're in luck. By the way,
by some estimates and criteria, the last year we had
seemingly zero superhero films was nineteen sixty five.

Speaker 3 (35:55):
That's funny.

Speaker 2 (35:55):
Yeah, I'm not going to go too deep on that.
I went slightly deep trying to figure this out, but
a similar case could probably be made for Dracula movies.
I could not give it get an exact year on this,
but I think the last year without a Dracula movie
was probably in the nineteen fifties of the nineteen sixties.
Periodical cicadas, however, these might be more comparable to adaptations

(36:16):
of the novel Dune, which occur only every sixteen to
twenty one years, so nineteen eighty four, twenty twenty twenty one,
with nothing in between. As long as you're not counting
sequels or part twos and so forth, if you depend
on seeing a new adaptation of the novel Dune by
Frank Herbert every year, you are going to starve to death. Okay. So,

(36:43):
periodical cicadas are native to the eastern and midwestern United States,
and they're famous for these lengthy subterranean nymph stages punctuated
by the synchronous emergence. So three species emerge every seventeen years,
and four species emerge every thirteen years. It makes them
one of the longest living known insects, though I believe

(37:06):
termite queens still top the list. It's something like fifty
years or even up to a century of life I
believe has also been suggested for turmite queens.

Speaker 3 (37:14):
But even if they're not the longest living individual insects
like that, period of development is crazy to think about.
So they in the case of seventeen years cicadas, the
hatchling falls from its egg, it goes underground, and then
it takes seventeen years before it comes up out of
the ground as an adult and adult again ready to mate.

Speaker 2 (37:37):
Exactly Now. I've read as well that that scientists something
of scientistsically think that by like eight years in they're
essentially ready to come up again. But they don't, and
we'll get into the whys of this, and a bit
like they still remain in this nimph stage, more or
less safely underground until the time of emergence has arrived.

(38:00):
So yeah, it's still amazing spending over a decade underground
in this nymph stage before emerging right at the very
end to just live out the last few weeks of
your life as this flying, breeding, noise making adult after
really a stealth existence as far as surface world life
is concerned, for just so terribly long as you've no
doubt heard on the news and perhaps witnessed in person.

(38:22):
Twenty twenty four is one of those rare years where
a seventeen year brood and a thirteen year brood sync
up with brood thirteen and brood nineteen emerging and expected
to number in the trillions. The brood system can be
a bit complex, but in there are multiple broods and
they're spread across different regions. Pretty much every year, periodical
cicadas are emerging somewhere. Sometimes they emerge later early, but

(38:47):
the count works for the most part. And we'll get
into even more about what this means here in a bit.

Speaker 3 (38:52):
Right, So, even in the case of the long dormant
periodical cicadas, there are often still some emerging somewhere, but
they might not be emerging in your region in any
given year, right.

Speaker 2 (39:05):
Right, So for this long period of time they're down there,
they're drinking the asylum. The nymphs dig deeper as they age,
they feed on larger roots. But this is key. They
always feed very slowly. Their metabolic rate is very slow
during the nymph stage, almost like they're in a state
of suspended animation, you know, and so their thirst does
not overpower healthy trees. But again, you can't help but

(39:27):
come back to this thirteen to seventeen year that it's
crazy to put this in human years, Joe. I don't
know if you saw this, but there was a Saturday
Night Live skit that did a fun send up of
this recently, where you had a pair of actors each
playing a cicada from each of the two major periodical
broods that are emerging. And so they're sitting there at

(39:49):
the news desk in their cicada costumes, one with the
two thousand and seven necklace around its neck and the
other one with the twenty eleven necklace around their neck,
and they're, you know, they're very excited to get out
there and mate and to fly into people's faces and shirts.
But they're also like making pop culture references to twenty

(40:09):
eleven in two thousand and seven, which I thought was
very funny and kind of like drives home the time
periods we're talking about.

Speaker 3 (40:16):
Here, seems like such an innocent time, all.

Speaker 2 (40:31):
Right, So we can sit around and wonder at this
you all day and just talk about how amazing it
is that they're so long lived and there's been so
much of it in this Nymph phase. But you know,
you come back to the basic question, why is this
the case? Why live underground in nymph stage for so
long and then remain in nymph stage past that eight

(40:52):
year mark when maturity has apparently already been reached, you know,
to go back to our hyper sleep sci fi analogy,
it's kind of like they haven't reached their destination yet.
You don't want to wake up halfway on the trip
to the planet that you're headed to in your spaceship,
and that would seem to be part of it. Though

(41:13):
it also raises additional questions like why have these cicada
species evolved to take such long nymph stages of more
than a decade? Like why are they why did they
set their why are their sites set so far out?

Speaker 3 (41:26):
Yeah, it's a fascinating question, and also the why, but
the how how do they manage that sort of timing?
How do they count the years?

Speaker 2 (41:34):
Yeah, they don't have iPhones down there with the alarm
clocks on them, and even if they did, even if
they put them in a battery mode, they wouldn't last
that long. According to Kritsky, the how involved here of
how they do it this in and of itself remains
somewhat of a mystery, but one theory is that as
they feed on the tree step, as they feed on
the xylum, that they're kind of hacked into the information

(41:57):
of the tree as well, like the fluid information, the
fluid flow of the tree, and that they somehow track
and remember fluid flow in such a way as to
time themselves.

Speaker 3 (42:07):
Yeah. So like the nutrition they get from the tree
varies seasonally, and with that mechanism, they can track the
passage of seasons.

Speaker 2 (42:16):
Yeah, which is crazy. Like I think it's one of
these things to kind of come back to David Eagleman's
Mister Potato Head explanation of how brains work with sensory input.
You know, it's like, if you have certain sensory input
coming into the brain, it will the brain will make
sense of that and use that information. So if you
could plug the stock market into your brain, like it

(42:37):
would make sense of that data. And so you can
I feel like you can kind of apply the same
thinking here, Like here's a creature living so long underground,
and to be clear, like not it's not in a
real state of suspended animation here. It's still moving around,
feeding and acting as a as an organism. But one
of the things that it is frequently connected to is

(42:59):
that fluid flow of the host plant, and like that
becomes perhaps kind of a sense in and of itself. Now,
as for why they do this. Most sources agree that
it has to do with disrupting the evolution of synchronous
predators and parasites. So when cicadas emerge, any cicadas emerge

(43:20):
annual or periodical, it is a feast. And this alone
is an anti predator strategy. It is a predator cetacean
so spawn or emerge in such high numbers that predators
can't keep up. They can't possibly eat everyone. Like how
many cicadas can you possibly eat? You know, random dog,
You can eat a dozen ovis, maybe two dozen ovus,

(43:43):
maybe three and get a little sick. But there's way
more of us than that. You cannot possibly eat all
the cicadas, And we're going to keep going around and
doing our business.

Speaker 3 (43:51):
If there are sharks in the water, you would rather
be one of a thousand fish than one of ten.

Speaker 2 (43:57):
Right, And so it ultimately comes into hitting these long
nipt stages just right, so that you prevent any sort
of to a certain extent, specific parasite predator threats from
evolving to depend on your emergence. So Kritzky writes, quote,

(44:20):
both seventeen and thirteen are prime numbers integers that are
divisible only by one and the number itself. It is
hypothesized that a long prime number life cycle for our
cicadas would make it difficult for predators or parasites to
evolve synchronous life cycles with the cicadas because there are
no intermediate life cycle steps that could easily evolve synchrony

(44:45):
with the cicadas.

Speaker 3 (44:46):
So if they were to emerge every year, like some
cicadas do in the same place, local predators could adapt
their life cycle to you know, to sort of like
save up, save up their appetite for that time when
all the cicadas are hanging around. Maybe they might you know,
they could adapt in a number of different ways, but

(45:07):
maybe they are able to starve themselves for some other
part of the year, knowing that the cicadas will reliably
arrive in May or June at this every year.

Speaker 2 (45:16):
Right right, And to be clear, we do have examples
where specifically parasitoid wasps have evolved to be in sync
with annual cicadas, the ones that come out every year. Remember,
parasitoid wasps in general are a great, highly evolved threat
to various insects and arachnids, using these other organisms as

(45:40):
hosts for their young either as you know, something left
in a paralyzed or you know, some half alive state
in some sort of a nest or a burrow to
then consume when they hatch, or in like true Zenamore style,
a warm body or I don't know about warm body,
but a body let's in which to deposit the egg

(46:02):
of your young so that it may hatch within and
then feast inside of the host organism and then emerge.
So this would be a threat worth evolving around and
creating strategies to avoid. But again, not every cicadas has
gone the periodical route. With the annual cicadas, we do
have specific cicada killer or cicada hawk wasps in North America.

(46:27):
With these solitary species, you have a female that captures
adult cicadas, paralyzes them with a sting, and then transports
them back to a burrow, and she'll collect multiple cicadas.
I've read as many as like one hundred cicadas in
this burrow, one for each egg that she lays. And
she knows what the sex will be of each egg,

(46:49):
so she'll she'll have one egg and she'll put that
that it will be a male egg, and she'll put
that on one paralyzed cicada and then there'll be a
female egg and that's that's going to be a bigger organism.
So it needs two to three cicadas to feast upon sick. Yeah, yeah,
but again, the cicada hawk wasp praise exclusively on annual cicadas.

(47:11):
These are the dog day cicadas, and they target them
during their regular emergence period. The late summer emergence periodicals
emerge earlier, so like they're just never synced up to
hit them. I have read that if periodicals, if some
periodical individuals are emerging late, they may end up being targeted,

(47:33):
but it's more of an incidental target. Like for the
most part, the periodical cicadas have evolved so that parasitoid
wasps cannot be in sync with them. And this has
to do again with these long nymph stages and prime
numbered emergencies.

Speaker 3 (47:47):
Now that's parasitoid wasps. But I've also read that when
the periodical cicadas do emerge, they are a food source
for basically every type of predatory organism out there, Like
everything eats them.

Speaker 2 (47:59):
Yeah, humans eat them too, And like I said, I
think in a later episode, we'll get into some of
the human culinary traditions surrounding the cicada. And in the meantime,
if you have eaten cicadas and or have any like
cultural experience with cicada cuisine right in, we would love
to hear from you.

Speaker 3 (48:17):
Well, if this strange prime number staggered periodical emergence has
these benefits in protecting against predator and parasite adaptation, why
don't we see more cicadas doing that? Like, why don't
all of the annual cicadas eventually evolve to be like that?

Speaker 2 (48:33):
Well? Yeah, Kritsky goes into this a little bit in
this latest book. He points out that we have actually
discovered a periodical cicada outside of the US that is
on an eight year cycle. This is a species in Fiji.
He points to another cicada species in India that's only
four years. I don't have additional information on these species,
but I guess one would assume that they benefit from

(48:53):
a different parasite prey threat array. And I guess in general,
when we don't see it more, My read on it
is that, on one hand, obviously an organism has to
have the capability to go through this sort of lengthy
nymph stage to and engage in the prime number of
emergence rates and so forth. And then also I guess

(49:16):
it's key to realize that there is this There does
seem to be this kind of balance between the periodical
and the annuals. So there will be annual cicadas in
areas that have periodical cicadas, And one wonders like, what
would happen to periodical cicadas if the annual cicadas just stopped,
if something, you know, wiped them out. You know, it

(49:39):
would certainly disrupt everything, maybe just cataclysmically for all cicada
dependent organisms, but maybe it would. It would result in shifts,
shifts that they might not be able to keep up
with for existing cicada parasites and predators. But again, the
thing that keep in mind about the cicada is that

(50:01):
it preys exclusively on annual cicadas, so like it has
no plan B outside of cicadas for continuing its life cycle. Now,
Kritzky also gets into the evolution of all of this,
which I thought was interesting. He writes that while cicadas
themselves date back to the time of the dinosaurs, periodical
cicadas again in we're talking about these North American varieties cicadas,

(50:28):
they're more of a recent evolution, he writes, Quote, the
seventeen years Septindecham and neotradecam ancestor diverged about five hundred
thousand years ago from the thirteen year Tridecam species. The
Cassini and Ducula species diverged from their common ancestor about
two point five million years ago, and their respective thirteen

(50:50):
and seventeen year species separated within the last three hundred
thousand years.

Speaker 3 (50:54):
Oh, so that's fairly recent. Yeah.

Speaker 2 (50:56):
He says the current array of North American periodical cicadas
was seemingly influenced by ice age glacial movements, specifically, quote
the formation of glacial refugia caused by the advancing ice
sheets and the subsequent habitat expansion that resulted from glacial retreats.

Speaker 3 (51:12):
Ah okay, So as yes, the ice is creeping down
closer to the equator and then retreating up that that
may have had something to do with the emergence of
these these differently these long dormant species. Yeah.

Speaker 2 (51:26):
Yeah, just you know, in general, changing and upsetting the
local ecosystem, creating niches and opportunities for changes in the
ways these organisms are operating and leading to speciation. And
so this is out of this we see the emergence
of these these new varieties of cicada that are engaging

(51:49):
in these long periodical emergence life cycles.

Speaker 3 (51:53):
Amazing.

Speaker 2 (51:54):
Yeah, all right, well, I think that's where we're gonna
cut it off for today. Joe, thanks again for for
working through the illness, but putting the sick in cicada,
so I think it ultimately works out. Again. We're going
to be back in a couple of weeks with more
on the cicada. We'll get into certainly get into some

(52:14):
history and myth and folklore, and probably some more just
general science about them as well. And in the meantime,
certainly write in with your experiences and thoughts regarding the cicada,
be the observational, culinary, folkloric, mythological, fictional, and so forth.
As a reminder, Stuff to Blow Your Mind is primarily
a science podcast, science and culture podcast, with core episodes

(52:37):
on Tuesdays and Thursdays and listener mail episode on Mondays,
a short form episode on Wednesdays and on Fridays. We
set aside most serious concerns to just talk about a
weird film on Weird House Cinema.

Speaker 3 (52:49):
Huge thanks as always to our excellent audio producer JJ Posway.
If you would like to get in touch with us
with feedback on this episode or any other, to suggest
a topic for the future, or just to say hello,
you can email us at contact stuff to Blow your
Mind dot com.

Speaker 1 (53:11):
Stuff to Blow Your Mind is production of iHeartRadio. For
more podcasts from my Heart Radio, visit the iHeartRadio app,
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