Seventeen-year Cicadas: Watching a Nymph Transform

Seventeen-year Periodic Cicadas have been emerging slowly and silently in my east Tennessee yard for the past week.  No drumming music to attract mates.  No sound at all.  (See more about this in my previous post:  Seventeen-year Cicadas Emerging in Tennessee.) But, for the past two days they have been more active, disappearing up into the trees.   And today it is sunny and 69 F degrees.  A moment ago, a cicada flew by me clicking.

This slow period has offered unexpected opportunity for me to see several nymph transformations.  The adult insect emerges from its nymph shell in a soft white stage, before the exoskelton and wings have had time to harden and become the mature insect we normally see.  If I had not seen Sir David Attenbourough's excellent video, Amazing Cicada Life Cycle, I would not have known I was looking at the same insect.  

I encountered this change as it was progressing and photographed it intermittently for 79 minutes.  These transformations are happening constantly as the cicada nymphs crawl out of the ground.  It is the most magical part of the whole metamorphosis and most of the time we don't even notice cicadas until they begin their deafening song.  That is, unless they are all over your garden.

Even when they are all over your garden, as they are mine, there is nothing to feel concern about.  They aren't feeding.  They fed like crazy on tree root sap under the ground for seventeen years.  Now all they care about is mating and starting their seventeen year cycle all over again.

Notice the wings starting to increase.  They expand rapidly as the cicada emerges from the nymph excoskeleton which then becomes an empty casing.

For a period of time they hang from their casing, drying and hardening the wings and exoskeleton.  Then their wings fold over their back, still with a silvery look, until the process of hardening changes the cicada into the black, red-eyed insect we normally see.

As the weather warms both the ground and the air, the quiet will fade and the air will fill with thousands of flying and singing cicadas.  For two weeks they will mate, lay eggs, feed wildlife and fertilize the ground.  Their larvae will hatch, fall to the ground, burrow under trees in search of root sap, and start the life-cycle all over again.  

This is the second in a two-part series on the seventeen-year cicadas in east Tennessee.  To see the first post visit:  Seventeen-year Cicadas Emerging in Tennessee

Seventeen-year Cicadas are Emerging in Tennessee

You will seldom see posts from me about insects.  I value them and appreciate their contribution to our natural world but they are not generally the focus of my art or my writing.  This insect, however, has my attention.  The Seventeen-year Periodic Cicada, also known as Brood-X, Magicicada septendecim.  

An insect that spends seventeen years underground, feeding on the sap of trees, only to emerge seventeen years later, for only two weeks, to sing, breed, lay eggs, and begin this life-cycle all over again. 

I've been through a seventeen-year emergence before, aware of it only because of the noise.  Thousands of males, all at once, flexing a drum-like organ in their abdomen.  It can be deafening.  But right now there is no sound.  There is just this slow, steady increase in numbers.  Speculation is that the temperatures have been too cold and everything will change when the ground warms up to 64F degrees.

This emergence is different for another reason. It is happening in my yard.  The quiet is eerie.  Does it mean only females have emerged? Are the males just two cold to sing?  East Tennessee's May has been unseasonably cold with many days hovering in the 50's F.  These cicadas are lounging near the ground, on ferns, viburnum, coral bells, even the ginger, any plant that happens to be nearby when they exit the ground.  They are also climbing the beech trunks and if you think to look over-head, you'll find them hanging out in the lower canopy.  

According to science, these insects like to emerge when its warm, a ground temperature of 64 F degrees at least.  But mine are emerging anyway.  Quietly, almost secretively.  Slowly.  The sheer numbers are starting to feel creepy.  And while we are waiting for the full effect, I want you to see what I refer to as the "fairy princess" phase of cicada metamorphosis.  

I think this phase is magical, the beautiful, delicate wing pattern and lovely yellow trim.  And yes, that other-worldly face. You can see more of that in my next post as I show you just how the cicada looks emerging from that empty casing we often see left behind.