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Periodical cicadas, that emerge every 17 years, are creating a buzz across SW Iowa. You’ll see and hear this harmless insect from now until mid-July

Published: Wednesday, June 11, 2014 11:51 a.m. CST • Updated: Monday, June 16, 2014 5:15 p.m. CST

Their crunchy, brown shells can be seen at the base of deciduous trees all over Creston and southwest Iowa. Periodical cicadas are back. The beady-eyed insects first emerged from the ground in Creston about 10 days ago, shedding their exoskeletons and creating a buzz of discussion among locals.

John Henry — longtime owner of Henry’s Skateland in Creston — first noticed periodical cicadas last week. They were crawling on his roma tomato and bell pepper plants near his back deck on New York Avenue.

“I knew exactly what they were,” Henry said. “You live 85 years like me and you will see a few things. They aren’t hard to distinguish. You see them once and you tend to remember their eyes and brown shell.”

Until now, these periodical cicadas have lived below the feet of Henry and other Crestonians for the past 17 years, burrowed 18-24 inches underground as nymphs feeding on the sap from tree roots.

Now that they’re emerging, though, cicadas will not only be seen in Union County, but in 45 other counties across Iowa this spring and summer. (See map on page 2A)

So, how did these insects know 17 years had elapsed and it was time to surface?

“Well, they don’t have calendars down there,” said Ken Holscher, associate professor at Department of Entomology at Iowa State University, laughing. “We do think their emergence is predicated on hormone levels. They seem to know when it’s their time to mature, become an adult and carry on with the next part of the life cycle.”

Holscher did say, though, there have been reports in previous years of these cicadas surfacing a year early.

Sound off

This year’s brood of cicadas will stick around until mid-July, flying clumsily through residential areas and woodlands. If you haven’t seen one yet, don’t worry. You will likely hear them.

Holscher said the male cicada “sings” from about 10 a.m. to mid-afternoon.

“They make a fluctuating, high-pitch buzzing sound,” Holscher said. “The sound is like nails on a chalkboard for some people. Others like the melody at least for few days, but then would rather they be quiet. My advice: Get out and enjoy the sound. They won’t be back for another 17 years.”

This melody is actually a mating call being belted out by the male cicada. That melody, at close range, can reach near 100 decibels, which is equivalent to a power saw being used 3 feet away.

Kevin Blazek, director of Adair County Conservation Board, said thousands of periodical cicada have invaded the Middle River Forest Area — a 49-mile river trail and primitive camping area between Winterset and Greenfield.

“More emerged yesterday,” Blazek said. “The singing has started. I could hear them this week in the forest area with my windows up, and I expect it to get much louder over the next couple weeks.”

After mating, the male dies shortly after and female will begin cutting slits — about the size of a pencil — in the limbs of nearby trees to plant her eggs. The female lays about 24 eggs in each slit and will deposit up to 600 eggs this spring.

“It’s estimated each tree could have up to 40,000 cicada nymphs,” Holscher said.

The eggs hatch in about 6 to 7 weeks. The new cicada nymphs then fall to the ground, bury themselves under 2 feet of soil — like their parents and grandparents — and begin snacking on tree sap for the next 17 years.

“We’ll see them again in 2031,” Holscher said.

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