Bug Expert Explains Why Cicadas Are So Loud

[Reporter] The sound of the periodical cicadas

emerging in the East Coast and Midwest is unmistakable.

It's a symphony.

Hi, my name is Samuel Ramsey.

I'm an entomologist with

the United States Department of Agriculture.

I study insects.

[cicadas calling]

Last night, I spent a good portion of my night

watching these cicadas beginning to emerge.

Watching them as they climbed up fence posts and trees.

It was a magical experience.

I couldn't stop myself from grabbing a few.

[Reporter] Cicadas are the loudest insects on the planet.

And according to some estimates, this summer's brood 10,

which has lived in the soil for 17 long years,

could number in the trillions.

Oh yeah, like the national debt kind of trillion.

[Reporter] That means that in some places

there are as many as a one and a half million of them

per acre, crawling out of the dirt

and up into the trees where they shed their exoskeleton

and begin to emit a piercing sound

that seems to undulate.

[cicadas calling]

So we are listening to a chorus of male cicadas.

So in order to actually amplify the sound

that they're producing, cicadas will chorus together.

They will gather together

and create a very loud song that they're presenting

to the female cicadas of the world.

They are not just producing one sort of noise.

It's an intricate sound.

So this is the sound of one cicada.

[cicada calling]

They can be pretty loud.

They're ranging in some ways from traffic noise

[traffic rumbling]

to pretty loud garbage disposal.

[disposal grinding]

[cicadas calling]

It is not a quiet insect.

[Reporter] So how does such a big sound

come out of something so small?

The answer lies in the cicadas unique anatomy.

This guy right here,

if you see that white patch right there,

that is the cicada's tymbal organ.

It is what's capable of making that really loud noise.

And there's one on each side of the cicada's body.

They're generating this sound,

unlike the ways that most insects generate noise.

We think of noisy insects, and we think of crickets.

[crickets chirping]

We think of Katydids.

[katydid rattling]

But when we hear the sound generated by a Cicada,

it's not generated by rubbing two parts

of its body together, they're pulling on a section

of their body that is arranged like a musical instrument.

And as they pull on the tymbal,

it buckles these ribs on the sides of their body

that makes this very resonant, loud sound.

In addition to that, the back end of their body,

like a lot of musical instruments, is hollow,

such that it can amplify this noise.

And then their wings allows them to direct it

in different directions.

So they are pretty much a musical instrument, all their own.

Something that immediately strikes me as really unique

about it is that it has a sound in a lot of ways

similar to something called Tuvan throat singing.

And it's a type of singing

that has some religious significance.

If I were to give you a very amateurish example,

sounds something like...

[throat singing]

And it's a type of singing

that some religious significance.

Person is able to, through humming and vocalizing,

create sort of two sets of notes playing at the same time.

[bees buzzing]

Other insects, like bees, don't typically

use their sounds to communicate over large distances.

Bees will create these vibrating noises

that they can use to communicate

with other bees, to communicate with organisms

that they're attempting to ward off.

But those are creatures that are

pretty close to their colony.

So there's no need for those sounds to be very loud.

[Reporter] Their blood red eyes and piercing shriek

might inspire fear in some, but not Dr. Sammy Ramsey,

who knows that the song of the cicada

is a key component to their survival.

This cicada is not capable of harming me in any way.

The only defense that they have

is that their numbers are so large

that nothing could possibly eat all of them.

And so when they get into those trees

it is evolutionarily favored that they make as much noise,

that they make the loudest sound possible.

Because if the loud sounds are going to attract the females,

well they want to make sure

that they can attract a female as quickly as possible,

before something comes along and attempts to eat them.

They have the hugest biological imperative to mate,

to find someone who's going to be interested in this sound.

And so in order to do that

they may have to really create a rather vibrant,

very loud noise that can attract females

from quite a distance to ensure that they haven't spent

17 years below ground for nothing.

The cicadas have two typical songs.

One of the songs of course,

is the one that we've been discussing

as this reproductive imperative

for them to attract the attention of females.

So with the cicadas, it's all about this song

that they're able to produce.

And the males that are able to produce a louder song

likely have larger muscles, are potentially bigger males.

And that may mean that

they're better at acquiring nutrition,

and thus have genes that would make them a better father

of the offspring of that female.

The males are doing this all together.

And then they're listening

at the same time to see if they can

potentially hear the responsive clicks

that the female will make if she is interested in him.

Now the female makes a sound like this.

[cicada clicking]

It's not unless you get a female cicada very close to you

that you'll be able to hear somewhat

subtle clicking noise that they make.

That noise is not supposed to be incredibly resonant.

It's more of a directed noise to get the attention

of a male that's close by.

And they get so excited about this

because of all the time that they have been waiting

for this, that they will go after anything,

and I mean anything, that makes a rhythmic clicking noise.

And so that's power tools that people are using outside,

that's lawn mowers, even just snapping can be something

that can attract male cicadas to you.

But the other song is a warning call.

This is the distress sound.

[cicada rumbling]

It seems to be a call to actually make sure that the rest

of the population of cicadas can get away and not be killed.

And so it's remarkable, but cicadas continue to show

that they have an all for one, one for all

kind of dynamic going where they are intently

trying to make sure that they can pass on their genes,

and that those around them can as well.

[Reporter] Once they've mated, the females lay their eggs

in the trees and die within a few weeks.

10 weeks later their eggs hatch.

The larva fall and burrow into the ground.

And the 17 year cycle begins again.

Just beautiful.

I know that it's fairly easy

for people to hear this and think of it

as just a bunch of loud, random, purposeless noise.

But these creatures, the sound that they're producing here,

it can even create an emotional response

for you to consider what they have been through,

and what they are looking forward to.

I can't stop drawing parallels between us

and the pandemic, and all over the world.

As people have had the opportunity to reach

a sense of normalcy after being in these situations

where they're isolated from other people.

And it seems like we aren't that different

from these creatures after all.

They look so different,

but they're after so many of the same things.

They're after comradery, they're after the opportunity

to be with other individuals, and they love music.

The cicadas are about to make some things happen.

And it is truly a bop.

It's a certified bop.

And I hope that you are willing to really

listen to it for what it is.

♪ Girl I'm telling you ♪

♪ You are the only one ♪

♪ I've got these big red eyes for ♪

[cicadas calling]