Wednesday, April 27, 2011

Periodical Cicadas

Periodic Cicada- MDC
This month's Missouri Conservationist magazine prepares readers for an exceptionally loud spring.  In the News and Events, Jim Low writes that The Cicadas are Coming.  This is the year of the return of hordes of 13 year cicadas.

There are 2,500 plus species of cicada (Latin for "buzzer") around the world.  In many countries they are considered a culinary delicacy, usually skewered,  fried in deep fat, or stir fried depending on the culture.   Note to the Outdoor Cooking Class.  

Following mating, the female cicada slits the bark of a tree and lays its eggs.  When the eggs hatch, the larvae emerge and fall to the ground where they burrow down from 1-8 feet.  After a period of time, 2-5 years for most species, they emerge ready to take on the responsibilities of adulthood.

We have all seen their exoskeletons clinging to trees, something for kids to collect every summer.  In some cultures these are thought to have medicinal properties.  Cicada pump body fluids into their thorax, expanding it until they split out of their exoskeletons.  They then pump these same fluids into their wing buds to expand them before drying.

The male then sets about courting with his strident and insistent song, the loudest in the insect world.  Held close to your ear, he can reach 120 decibels, louder than a Lead Zeppelin concert.  The call is made by contracting muscles on its membranous tymbals, a mechanism Jim Low likens to the " sound of a plastic soft drink bottle popping back into shape after being compressed."  The call prompts every other male in earshot to join the chorus.  It makes you wonder how a female can ever decide on which one to mate with.

The 13 and 17 year periodical cicadas are particularly interesting.  No one knows how they keep track of time, but they have it down to a fine art.  There was an unusually large brood in 1998 so biologists are expecting a loud spring, starting in late April through June.

What is the advantage of a sudden mass emergence?  For one thing, it swamps their predators such as birds, cicada killer wasps and even fish.  They can't possible eat all of them and therefore there is a successful mating season.  Jim says that fish get used to feeding on them and will hit any lure resembling a cicada.  Time to head to Bass Pro again.

This Missouri Department of Conservation site has more information and a recording of the cicada chorus for those who never venture out of doors.  Shame on you!

2 comments:

  1. It's Led Zeppelin...having been to one of their concerts, I can attest to that.
    Growing up in Houston, TX, we were quite familiar with that sound on a daily basis as soon as the temperature hit the lower to mid-eighties.

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  2. Led Zeppelin is a good analogy. It also applies to the crowd control of its audiences. See Periodic cicada II on June 3.

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