APRIL
2004

 

 

 

By
Tom Turpin
 
Professor of
Entomology
Purdue University

 

 

 

 

 

04-08-04

Batten Down the Hatches! It's Going to be a Cicada Year!

It will be one of those years when they show up again.  Grab the women and children and batten down the hatches!  There is no place to hide when they show up.  They'll be noisy.  They'll be zooming from tree to tree.  They'll dive bomb from the sky so frequently that even the infamous Red Baron would be amazed.  They are cicadas.

Not your old run-of-the-mill cicadas that show up every year in late summer.  No siree Bob!  These are periodical cicadas.  They are insects with black-colored bodies and orange wing veins.  They have large, menacing red eyes.  And they show up in great numbers in some areas.  As many as one million per acre!

This is no made for TV science fiction movie.  This isn't a National Geographic special filmed in some far off place.  This is a real life adventure in our own back yards.  And it happens once every 17 years.

Periodical cicadas get their names because of the periodicity of their life cycle.  They have a life that is 17 years long.  So they show up periodically, every 17 years to be exact.  That means that the cicadas that will emerge this year began their life in 1987.

Seventeen years ago Ronald Regan was president and Margaret Thatcher began a third term as prime minister in Great Britain.  There was a large earthquake in Los Angeles. Popular TV shows included the Cosby Show, Golden Girls, Matlock and Murder She Wrote.  And 1987 was the year that Prozac and the Nike Air Trainer were introduced.  That also means that the cicadas that emerge this year are the same age as most 2004 high-school graduates!

This group of cicadas are known as Brood X.  Not to be confused with Generation X which has to do with people.  Brood numbers are used to identify specific groups of the periodical cicadas.  Brood X is geographically the most widespread of the broods.  It is the most common in Indiana, emerging in all counties with the heaviest populations in south-central portions of the state.

Another confusing aspect of the periodical cicada is that there is also a 13-year strain of the insect.  This strain is more common in southern states but there are two groups in Indiana with their most recent appearances in 1998 and 2002.

So what have those cicadas been doing for the last 17 years?  They have been sucking sap from the roots of trees.  Following egg laying, which occurs under the bark of the twigs of trees, the newly-hatched larvae drop to the ground and dig into the soil.  Once completely developed, they crawl close to the soil surface.  Then in late May and early June the insects crawl out of the soil.  As they do this they construct little chimneys of dirt. 

The cicada nymph crawls up on something like the trunk of a tree, a post or a picnic table leg where it will emerge into an adult cicada.  The emergence from the last nymphal skin is accomplished with a split down the back of the thorax.  The snow-white insect then crawls from its old skin and hangs on the bark until its exoskeleton firms and colors, a process known as tanning. 

Tanning takes a few hours and during this time the newly emerged insect is soft and can't fly and is vulnerable to predators.  That is why most cicada emergence occurs at night when the insect is protected by darkness until it gets its wings.

Following emergence the cicadas flaunt their new-found freedom by singing and flying around.  It is the male that sings as a way of attracting a mate.  All of the noise is made by love-seeking males.  For those of you who offended this year by the cicadas racket just thank your lucky stars that female cicadas can't sing!         

 

Writer: Tom Turpin
Editor: Olivia Maddox