|The periodical cicada (Magicicada septendecim) A female inserting eggs with her ovipositor into the under surface of an apple twig - Picture courtesy of Wikimedia Commons|
According to Dr. Gene Kritsky, Professor of Biology at the College of Mount St. Joseph, and author of the book, Periodical Cicadas. The Plague and the Puzzle
Periodical cicadas are spectacular insects, often making sudden and dramatic appearances. Alexander and Moore wrote in 1962, "The periodical cicadas make up a truly amazing group of animals; since their discovery 300 years ago, the origin and significance of their extended life cycles have been a continual source of puzzlement to biologists. Their incredible ability to merge by the millions as noisy, flying, gregarious, photopositive adults within a matter of hours after having spent 13 or 17 years underground as silent, burrowing, solitary, sedentary juveniles is without parallel in the animal kingdom."
Map of Predicted 2013 Brood II Emergence. Picture courtesy of Magicicada.org
- Cicadas emerge after the soil temperature exceeds 64º F, which is usually in late May.
- Only the male cicadas sing. They have sound-producing structures called tymbals on either side of the abdomen.
- It is easy to tell male cicadas from female cicadas. To do so turn the cicada over: the female will have a groove in which is found the ovipositor; the male’s abdomen will terminate with a square shaped flap.
- There are three species of 17-year cicadas, which will emerge in 2013. They are named Magicicada septendecim, Magicicada cassini and Magicicada septendecula.
|Magicicada - Picture courtesy of Gene Kritsky|
Apparently, Brood II is a well-known brood of cicadas. Thomas Jefferson wrote of their emergences in 1724, 1741, and 1775.
I spent most of the day Wednesday (3/20/13), home sick nursing a cold, having bad thoughts about Punxsutawney Phil's poor prognosticating prowess, and perusing the Magicicada.org web site to learn more about these insects.
They are native to and only found in eastern North America.
There are 12 broods of 17 year cicadas, and 3 broods of 13-year cicadas designated by convention using Roman Numerals.
They can't bite or sting, and have minimal impact on plants and shrubs in your landscape, with the possible exception of young trees or shrubs where the female's egg laying organ can girdle pencil thick woody stems or twigs. More FAQ's here.
And as a Math Geek, I also wondered why do these critters appear in cycles of 13 and 17 years? 13 and 17 are prime numbers - is there a connection?
Well, no one really knows for sure, but Predation Pressure is one thought. See studies here and here.
I will definitely keep my eye out for any stragglers that appear around in this area, and may even plan a trip to my home state of New Jersey this summer, just to observe, and appreciate the show.
Update: Sunday, March 24, 2013: Via the magic of Facebook, a 'Friend' coincidentally noted that Brood II was coming, and linked to this marvelous web page that I missed when I put this post together - CicadaMania:
We are dedicated to providing news, video, audio, photos and information about cicada insects found all around the world. Cicada Mania was established in 1996 during the Brood II periodical cicada emergence, and since then we have continued to add content about Magicicada periodical cicadas, other North American species, and cicadas species around the world. 2013 marks our 17th year, just like the 17 year lifecycle of a Magicicada periodical cicada.They have a Facebook Page, too, whose page I have 'Liked' and a series of 'YouTube' videos and sounds that will keep me occupied in the weeks ahead.
Enjoy! I know I will.
Update: Sunday, April 14, 2013: Here's a time lapse video of a Magicicada molting, courtesy of CicadaMania:
And Dr. Kritsky is asking for some help in veryifying his emergence prediction model, so anyone in the expected area, who wants to do some "citizen science" research, is asked to note when you saw your first cicada, and when they appeared in large numbers. Send the information via email to Dr, Kritsky, along with your address. Details here. MG's, school groups, or any interested parties are encouraged to participate.
Update: Wednesday, April 30th. Wonderful article by Kevin Ambrose writing for the Washington Post, with lots of good information, charts, and his memories of previous year's emergence.
Update: Thursday, May 23. More on the Prime Number thing from Scientific American:
The fact that the surviving periodical cicadas have life cycles built on prime numbers may have conferred key survival advantages. A prime-numbered lifespan means that predators cannot match their own shorter life cycles to the availability of cicada prey. For instance, if the cicadas had even-numbered lifespans, a predator with a two-year life cycle could expect a cicada feast, and a subsequent population bump, every few generations, because all even numbers are divisible by two. As explained in 2001 by a trio of researchers from the University of Chile and the Max Planck Institute of Molecular Physiology in Germany, “a prey with a 12-year cycle will meet — every time it appears — properly synchronized predators appearing every 1, 2, 3, 4, 6 or 12 years, whereas a mutant with a 13-year period has the advantage of being subject to fewer predators.” Prime numbers are still divisible by themselves and by 1, of course, but they have no other divisors.
On the other hand, prime lifespans may relate to periodic overlaps between different cicada species, rather than overlaps between cicadas and their predators. The two prime-numbered life cycles of Magicicada ensure that asynchronous broods rarely interact where their geographic ranges overlap — a 13-year cycle and a 17-year cycle match up only once every 221 years. Those rare meetups may confer the advantage of preventing the two groups from mating and producing hybrid offspring.Read more here.
Update: Friday, May 24. More on predation saturation, "It's an idiot bug." But with evolutionary smarts, apparently.
Update: Wednesday, May 29. Science Magazine Nature, tackles the prime number question, suggesting, counter-intuitively:
"...proposes that the masses of cicadas trigger long-term changes in the forest that end up causing bird populations to crash after 13 or 17 years. The mechanism remains a mystery, but Koenig notes that one factor could be the flood of dead cicadas, whose bodies are 10% nitrogen. The die-off sends a pulse of fertilizer into the forest that temporarily enhances plant growth but could later lead to unfavourable conditions for birds. “It’s a pretty weird hypothesis,” he admits."