Cicada nymph skin

2008 December 13

Back in the beginning of September, S_ and Sam were out for a walk in the woods when they found this clinging to the side of a tree:

Tokyo must be destroyed!

Tokyo must be destroyed!

It’s not the whole bug, it’s just the skin. There was originally a Cicada inside. As far as I’ve been able to find out, we only have one species of cicada in this area, the Dog Day Cicada, Tibicen canicularis. [1] These are the ones that make a screaming noise that sounds to me a lot like someone cutting sheet metal with a power saw. So, even though the nymph skins of all the cicadas look a lot alike, we can be pretty sure of the species of this one just because of when and where it was found.

Even though it’s just the skin, it is almost as good as having the whole bug. All the surface details are still there, you can clearly see the eyes and the fine whiskers on the face,

and even the antennae are still clearly visible and distinct.

As big (about an inch long) and scary-looking as this is, the nymphs are completely harmless. Those honking big, hooklike front legs are adapted for digging, not for carving out chunks of flesh. They actually lead very quiet lives. The nymphs hatch out from eggs laid under the bark of tree branches, and drop to the ground where they dig until they find a tree root. Once they find one, they latch onto it and start sucking on the juices.

They keep this up for a long time. Years, in fact. The dog-day cicadas stay underground for about three years, but some other species of cicada (the periodic cicadas that live further south) stay down there for seventeen years. It takes them a long time to grow this way, because tree sap is not all that nourishing, but eventually they are fat enough to dig their way to the surface and climb up the trunk of their host tree. Then they crack open their backs to emerge as adults, leaving behind their old skins for the amusement of small children, and to provide homes for other small insects. Like this earwig.

[1] I have since found out that I was mistaken about other cicadas. There are at least two other species of cicadas living in our backyard. And this shell could have been from any one of the three species we have captured as adults so far.

5 Responses
  1. December 13, 2008

    First of all, the earwig-in-a-skin picture is awesome. Nice photo.

    Second, this article would be freakishly scary if today was opposite day. Here’s the way I accidentally read one of the sentences above:

    Those honking big, hooklike front legs are adapted not for digging, but for carving out chunks of flesh.

  2. December 13, 2008

    Earwig! Cool beans!

  3. December 18, 2008

    We get the Tibicen linnei cicada down here in Iowa/Illinois. And we see the shells everywhere, too. Great photos!

  4. December 20, 2008

    Finally! A photogrpahy subject that doesn’t try to run away, fly off, squirm about or bite and pinch you.

    Unless it’s a zombie cicada. You need to watch for that. There’ve been reports of zombie cicadas up in your neck of the woods.

    (Another outstanding post!)

  5. sublunary permalink
    December 29, 2008

    Wow, I used to love playing with these skins as a kid. (And the mymphs and adults when we could catch them) It bothered my mother to no end.

    However, that last picture, with the earwig poking out of the skin, really freaks me out for some reason. Makes my skin crawl in a way bugs usually don’t.

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