Hi everyone and welcome to a very special episode of Curious by Nature.
My name is Allen and I am one of the entomologists here at the Nature Museum.
By now, you may have heard the news that trillions of cicadas are emerging across the country
in upwards of 15 states!
I just had to go on a trip to witness this mass emergence for myself.
There is so much to share about these fascinating creatures that we actually had to make
a two-part special here on Curious by Nature.
Today, as we take a look at the emergence of Brood X, we’re first going to learn about their populations,
their long lifespans, and the sounds they make.
Later in Part 2, we’ll take a closer look at what they do for the very short period
of their lives that they’re above ground.
So, we’ve got a lot to cover – let’s dig into some cicadas!
I headed down to east central Illinois and Indiana where the Brood X cicadas live.
Cicadas are common insects occurring across North America,
but there are so many different kinds.
You’re probably familiar with some of them, since here in Chicago we do see
and hear them every year in the late summer –
(cicadas calling)
these are called the dog day cicadas.
But the cicadas which are famously known for emerging en masse only after a long period of time
are the periodical cicadas.
Distinct populations of periodical cicadas are grouped into broods.
Brood X, the one that is emerging this summer, only comes out every 17 years and it is the
largest population in the US – which is why so many of us are excited to see them!
Periodical cicadas are smaller than dog day cicadas.
They are different in color – they’re orange and black rather than green or brown –
and have a synchronous life cycle.
That means the majority of a given brood’s population will emerge at about the same time.
Occasionally you may find stragglers that emerge at the wrong time, typically one or
four years before or after the rest of them.
The dog day cicadas on the other hand are asynchronous, so there are some out and about
every year.
Now what I find most fascinating about periodical cicadas is that they spend 13 or 17 years
of their life, depending on which brood, underground.
As far as insects go they’re practically ancient!
Most insect lifespans are a matter of months, not years.
Broods in the southern US emerge in 13 year cycles, while those in the northern states
have 17 year cycles.
Brood X, also known as the Great Eastern Brood, consists of 17 year cicadas.
That means their last mass emergence was back in 2004.
Cicadas are probably most well known for the characteristic sounds they produce.
Individually these periodical cicadas aren’t particularly loud,
(wind blowing, solo cicada calling)
but when they all sing together their volume is unreal and it’s part of what makes this brood’s emergence
a magical experience to witness.
Their singing serves as a mating call.
The males are trying to attract female cicadas to come to them to mate.
They will gather among the trees and form chorus centers, and the louder the sound,
the more female cicadas will be drawn in.
You may have noticed that the singing cicadas don’t all sound the same.
Listen carefully, how many different kinds of calls can you hear?
(cicadas calling)
Different species of cicadas each produce different calls.
17 year cicada broods can comprise up to three different species!
They all look alike, but their calls are unique.
Now, a given species can have more than one call so it does get a bit complicated,
but my favorite is the aptly named seventeen year cicada, Magicicada septendecim.
They are also called the pharaoh cicada because it’s said that’s what their call sounds like.
It goes phaaaaaaaaaraoh, phaaaaaaaaaaraoh.
Can you hear it?
(cicadas calling)
While I love the sounds of cicadas, they really won’t be around for long, only about a month!
And they have a lot to do during that time.
But what exactly are they up during their short stay above ground?
Why do they come out all at once like this?
And why now?
Join me in part 2 of our Curious by Nature cicada special to find out –
here’s the link!