|Asheville Natural is a guide to the native wildflowers of the southern Appalachians, with additional information for plant sources, hiking trails in the Asheville North Carolina area, and a few well-chosen links to other sites with Asheville information, wildflower sources, hiking,trail and outfitter information, and botanical resources. This is a non-profit site, created and maintained with love. All information contained on this site is based upon personal observation, and all photos are our own.|
The Invasion of the 17-Year Cicadas in North Carolina
First of all, let me say that this is dedicated to the patience and persistence required by biologists, botanists, entomologists and ecologists of all stripes. My own efforts pale in comparison to those of the pros. The two websites I have found most informational and helpful are www.magicicada.org and www.cicadamania.com.
I wish to express special thanks to Dr. John Cooley of the University of Connecticut Department of Ecology and Evolutionary Biology. Dr. Cooley is the wizard behind www.magicicada.org. He also has a profile site describing his research and background at http://hydrodictyon.eeb.uconn.edu/people/cooley/. He took time out from his very busy schedule to answer several emails from me, and to review this page for accuracy. Some of my early photos turned out not to be cicadas, but the mystery has been solved - I finally identified them as Ladybugs (Lady Birds, Lady Beetles.)
See my new Insects page for new photos and information about Ladybugs.
Thanks also to the Asheville Citizen-Times for contacting me for information about this amazing event. (See their Sunday May 15th issue.)
Additional information, questions and resources I can list are welcome - please email me at firstname.lastname@example.org.
In 2008, Asheville NC turned out to be one of the biggest centers, if not THE Actual Epicenter, for the emergence of the 17-Year Cicada (Magicicada septendecim), Brood XIV. This page is devoted to them.
I have done my best to chronicle their lives in both pictures and words. Actually, I got a late start with the photos but it turns out that their short lifecycle above ground covers a few weeks. So even though the first-emerged adults were beginning to die by June 1, others were still emerging from the ground.
May 12, 2008: This is the approximate date they first started to emerge from the ground in my area (Weaverville NC, just north of Asheville.) I say approximate because I didn't get out to my garden for a few days and hadn't noticed the huge numbers of abandoned shells until the 15th. So they must have started a few days before I noticed.
So far I have not gotten a picture of them emerging from the ground. What I did notice were huge numbers of holes that suddenly appeared in the ground around the house. Most of the holes were, well holes in the ground. But some were little mounds of dirt. These mounds tend to occur where soil is more pliable. They might fool you into thinking they're yellow jacket or wasp nests. Not so.
May 15, 2008: The first thing you're likely to notice are the newly-emerged adults and the last-stage nymph shells they've just left behind, like this:
But that's not the beginning of the story. Let's back up a little.
June 1, 2008: When the Cicadas have matured after spending 17 years underground feeding on tree root sap ( they do not damage the trees), they emerge from their deep underground homes to the surface and immediately climb up the first vertical surface they find. Hopefullly it's a tree and not your leg, but since they mostly emerge at night you're probably safe :-)
June 3, 2008: I found new adults just emerging - I believe the last ones for the season, I haven't seen any since. So, the emergence does seem to span a few weeks.
When they emerge from the ground they are encased in a very soft final-nymph-stage shell. Very vulnerable, which is probably why they emerge at night. Very quickly they climb up what they believe to be a tree - but anything will do! This is what they look like about 15 minutes after emerging, their final shell hardening along the way:
Next, in a very short period of time, they emerge from this shell in their fully-adult form - almost. At this point they are called "teneral" adults. Following are several pictures of the emergence. By the way, these are the ones you're supposed to eat :-)
At this point the Cicada simply rests while the veins in the wings fill with fluid until they are full size and ready to go. Meanwhile the outside of the body begins to harden. It may sit in the same spot for a day or three, or may continue to climb upward as it matures. Within a few days it will be in the treetops.
Now we're back where I started - a newly-matured adult.
But the story doesn't end there!
Now they've got to get busy mating and laying eggs before their long life ends in the next few weeks of final glory.
Good grief, these critters are LOUD! No doubt because I seem to be smack in the middle of a maximum population explosion. The males do most of the "chorusing" up in the trees, from dawn to sunset. Sometimes they also respond to moonlight in the middle of the night. A friend of mine finally identified what they reminded us of - the phasers on the original Star Trek® series :-) I find it quite pleasing and relaxing as I work from my home office, but I think they're beginning to send my husband around the bend!
So what's making all that noise? The males congregate in the treetops in large groups, forming a "chorus" intended to congregate the males and attract females. The males have a special organ just beneath their wings called a "tymbal" that vibrates to create the loud noise we hear all day long. And, their abdomens are hollow, which amplifies the sound just like a drum would. Below are photos.
When a male cicada attracts an interested female, he will emit a "calling song." Until recently, it was believed that Magicicada septendecim females had no response call. However, Dr. Cooley is credited with establishing that the females do indeed respond sonically with a "wing flick".
How to tell the difference between male and female:
Following are several photographs from above and below, showing each sex. The key point to look for is the tip of the abdomen. A female has a much more tapered abdomen. The male has a fatter (hollow) abdomen and a prominent "protrusion" (typical of them isn't it!)
June 11, 2008: I have been watching. We're definitely now seeing signs of "flagging" in the trees, which is the term for branch die-off. It is confined to the very outer branches, and the Cicadas definitely prefer oaks (red oak over white, I think):
Flagging itself does not seriously harm anything but the youngest of trees - think of it as natural pruning. It is caused by adults feeding on the sap of the tree branches, and the egg-laying, but is limited to the outer reaches of the branches, causing no permanent harm to any tree over a couple of years old. Though I must admit, they basically managed to "top cut" a young, small Japanese maple in my mother's garden.
I have also noticed a slight drop in the volume and daytime extent of the adult cicada chorusing, indicating they are probably due for a complete die-off by July 15 (8 weeks after I first noticed the emergence.)
All the expert sites say that the first nymphs (the first emergence from the egg, technically called the first "instar") will fall from the trees and head underground. What I wonder is - do they dig new holes? Do they follow their way down the holes this year's adults emerged from? I don't know! I haven't found any answers to these questions yet.
An explanation of "instars" and the 17-year cicada life cycle: All the technical info I can find indicates that the newly-born hatchlings go directly underground, where they will undergo 5 "instar" stages (basically, outgrowing their skins and emerging in a slightly more advanced form, until they finally emerge from the ground 17 years later as a final-stage nymph ready to break out of their "shell" as an adult. Many types of insects go through these instar stages.)
Friday, June 13th - a Lucky Day for Cicada-Haters :-)
The noisy chorus in the trees is still there, but definitely a lot quieter than a few weeks ago. Their job done, the adults are dying and falling to the ground, making that "mess" on sidewalks and yards that no doubt gross out more than a few folks. So far, the vast majority of dead adults have been males. I surveyed a 1-meter square in my woods and found 22 dead males, and only one dead female. But more casual "browsing" around my yard has included a few more females. So I still predict about the first week of July for a noticeable reduction in the noise - but a noticeable increase in the mess!
June 15, 2008: Caught in the act!
I finally got a picture of a female laying her eggs. She was working on a blueberry bush in my mother's garden. Females will lay small nests jut under the surface of the bark (in this case, a woody stem about 3/8" in width/diameter.) Each female will dig a number of nests with 20-30 eggs each.
My mother has a fairly extensive garden, so I decided to take a look at what types of plants were being selected for egg-laying. Her flowering annuals and perennials, and most ornamentals, were left alone. Her crabapple trees, peach tree, raspberries, flowering quince, peonies, hollies (both evergreen and deciduous), redbuds, native dogwoods and rhododendrons seemed to be fairly safe. They definitely like her blueberry bushes and azaleas unfortunately, and I found one female busy laying eggs in an asparagus stalk. Following is a picture of new nests on a blueberry bush:
The females lay their eggs just under the surface of a tree branch. The eggs look like tiny grains of rice but you won't see them unless you cut the branch open:
The (blueberry) branch in the above picture is 1/2 centimeter in diameter. The eggs are just about precisely 2 millimeters in length. I had hoped to say that "no Cicadas have been harmed or killed in the making of this website" but obviously, these ones aren't going to make it. I had to cut the twig open to find them. One solace, they were probably going to drown anyway because they were located at the very bottom tip of a cutting I took (now sitting in a glass of water) with lots of nests on it, in hopes I can catch them hatching. (In all other cases, I have taken live photos or pics of ones that I found already dead.)
There is VERY little info online about what happens to the new brood after they hatch out. I am hoping I can keep my blueberry branch alive, and document the new hatchlings - then release them.
For those who have been driven insane by the noise, they are definitely much quieter now. No doubt the males are dropping like the proverbial flies - though the females are certainly very busy right now laying their eggs.
A note on wildlife - I usually have a flock of resident wild turkeys, and by now I should be seeing hens with dozens of poults in tow. I haven't seen a sign of them. So I'll bet they're out there gorging on cicadas in preference to the cracked corn I leave out for them.
Meanwhile, www.magicicada.org is the place to go for beautiful photos and excellent information about their life cycle, diseases (there is a specific fungus that infects them), predators, and more.
June 17, 2008: The roar has become a gentle whisper, much to the relief for some folks. The pictures I thought might have been 13-year cicadas dug up from the garden, I'm pretty sure aren't - but I also have no idea what they are. Oh well, on to another identification and learning adventure!
July 4, 2008 Update: The sound of adult cicadas has definitely stopped, except for one single singer I heard late this afternoon. Meanwhile, I've got my thoroughly dead blueberry branch in a vase in the kitchen - I'm waiting for the eggs to start hatching so I can take pictures.
I have a theory about how the tiny new nymphs reach the ground. It's obvious that this year's siege has caused the very outer branches of many trees to die. They all contain a whole lot of cicada eggs - the egg-laying seems to be what causes the branches to die. It's known that when the new nymphs hatch out they will fall to the ground and dig their way down until they find a suitable tree root to feed on (which is not harmful). But notice how the outer tips of the branches have been chosen specifically for egg-laying. Then see what happens after a brief thunderstorm. All those branchlets have been knocked off and sent to the ground, long before the eggs hatch out. So folks, all those little branches of "dead" twigs you've been sweeping off the porch in the past two weeks means you've been helping the eggs get "close to home."
It's occurred to me to put a small oak tree in a pot and try to maintain a small population that I can observe underground over the years. Not sure I can manage that, and haven't decided - my primary motivation is to release any hatchlings I get. But it sure would be interesting to watch them grow over the years, if I can manage it.
July 23, 2008 Update: Ok, I've got this dead stick in my kitchen - I know it's full of Cicada eggs - but so far no sign of activity. I've been told to look for little castings of the first shells when they emerge. It also occurred to me that outdoors, they would get rained on - and maybe the eggs actually need some extra moisture to keep them alive. So I am occasionally spritzing my twig with water.
September 1, 2008 Update: I think I missed it. I've had an egg-full twig hanging over a black piece of paper since July 4th. All I'm seeing are tell-tale indications of cast-off eggshells but darned if I can find an actual newly-emerged numph. Drat. I'm cutting into the twig I've got but I don't think I'm going to find anything. The new cicadas are just as mysterious as ever, and I've got to wait another 17 years for these guys?! I'll try harder with the next 13-year cicada emergence, which in our area, should be soon.
I'm sorry to disappoint my readers because I really wanted to close the loop and document this year's emergent brood. I don't know what I've done wrong - maybe just didn't look at the right time or in the right place. If anybody has pictures or information about how the new cicada brood gets it's start, I'd love to post it - with full credits of course.
|A note on the nomenclature (naming conventions) on this site: Scientific names and classifications are constantly being argued and changed, and it drives me nuts. Although I use many different sources for knowledge, for naming consistency I use the "Manual of the Vascular Flora of the Carolinas" by Radford, Ahles and Bell, 1968 edition. This book is a well-established authority for the plants of our region and I've been using it for years. If for some reason I must use a different source for a particular plant, I will make note of it within the descriptive text. Don't like it? Tough!|
All contents of this website ©1998-2008 Weaversites. All rights reserved.