If you’re around Ames this summer and visit Ledges State Park in late May through June, you will experience a buzzing that only comes once every 17 years.

2014 is the year that the periodic cicadas will be emerging from the ground to reproduce.

They have evolved to wait 17 years before coming out of the ground.

Donald Lewis, professor of entomology, said that the periodical cicadas only come in June and stay for six weeks.

Lewis said that the 17-year life cycle is an evolutionary adaptation to avoid being eaten by predators. Within 17 years they will often outlive their predators and when they emerge in the tens of thousands, predators can’t eat all of the cicadas.

Female periodical cicadas lay their eggs in tree twigs. The eggs then hatch into nymphs and then they fall to the ground where they will live off of tree sap for the next 17 years.

Lewis said it isn’t certain how they know when to come out but it must be something to do with the changes in the tree.

Lewis doubts that the weather alerts the nymphs because it changes so much. They are buried several inches to two feet deep — not deep enough to escape freezing. He said that they have internal antifreeze that prevents them from freezing.

In central Iowa the life cycle is always 17 years, but there are also periodical cicadas that are on a 13-year cycle that live in other areas of the United States.

“There’s a difference between the 17-year cicadas, but it’s not as if they emerge everywhere in the United States at the same time,” said Ken HolscherCQ, an associate professor of entomology.

Periodical cicadas often emerge in different broods that are defined by location and when they emerge.

Lewis said that several researchers travel from state to state every year to follow the periodical cicadas and study their appearance. This year they’ll only be in Iowa and parts of Illinois, whereas last year they were in Virginia and Pennsylvania.

The periodical cicadas look different from the annual grayish-green cicadas. The periodicals have a black body, orange wing veins and bulging red eyes.

Even though it’ll get fairly noisy at Ledges this summer, Holscher encourages people to go see them.

Lewis said that it’s very different for an Iowa insect to have such a long life cycle, some other insects have a longer life cycle but it’s sort of an accident.

Scientifically, the study of periodical cicadas took off in 1893. Scientists were documenting what was going on and how it was happening.

Lewis said that the males buzz for mating purposes.

Holscher said that it’d be really neat to see them emerging from the ground. They’ll emerge by the thousands at night. The problem would be the timing, but if people saw them emerging they would see thousands of cicadas doing what they’re programmed to do — climb up into trees.