Every summer in Illinois, a distinctive buzzing sound fills the hours between sunrise and sunset. This sound belongs to the variety of cicadas that inhabit the state for the summer months to mate and lay eggs.

This summer marks the 17th year in their cycle, and the Champaign-Urbana community can expect more noise than usual.

A majority of these cicadas, known as dog-day cicadas, sport a green and brown body with massive compound eyes arranged similarly to those of a hammerhead shark.

Periodical cicadas make up the rest of the population. They differ from the dog-day cicadas by their distinctive black bodies, red eyes and a life cycle of 13 years in the southern part of Illinois, and a life cycle of 17 years in the northern part of Illinois. Periodical cicadas are divided into broods, a population of cicadas that inhabits a certain region of the state at a certain time of their life cycle.

Central Illinois and the Champaign-Urbana community can expect to hear singing from three different broods. Their mating calls vary from a constant buzzing to a rhythmic drumming sound to a clicking sound.

“They make an unbelievable amount of noise,” said Stewart Berlocher, professor of entomology at the University. “If you listen carefully, you can hear the three distinctive songs.”

Periodical cicadas earn their name from the distinct 17-year cycle in which they come out of the ground to mate and lay eggs. This distinctive cycle is actually a defense mechanism in order to avoid predators, which are normally on one-year or two-year life cycles.

“They will come out this spring (toward the end of May), from out of the ground, and climb up on trees and other upright objects,” said Phil Nixon, extension entomologist for the University. “Their backs will split and the adults will come out. The adults will mate, and in the process, the males sing to attract the females to them. The females hang around for another three weeks (after the males die) and they lay eggs inside twigs. Those eggs will hatch into nymphs, which free-fall to the ground, dig in and for the next sixteen years they sit on roots sucking out the sap.”

Nixon said that there have been reports in the Chicago metro area of 133 thousand cicadas per acre, with 2.5 acres comprising a city block. “More than three years ago, they were everywhere at Kickapoo State (Recreation Area),” Berlocher said. “The trees were crawling with enormous numbers of them.”

Despite the incredible number of cicadas, no real damage is done to the environment, Berlocher said. Some small trees may suffer weakened trunks, especially fruit trees. But older trees will only lose a few inches off their twigs from the females using their ovipositors to slice open the bark to lay their eggs.

“For me personally, aside from the loud singing and chirping, I don’t think it’ll really be a big issue,” said Daryl Swafford, sophomore in Communications.

Periodical cicadas are not only sources of protein for the predators who feast on them every 13 to 17 years but also for people, Nixon said. The insects have been known to taste like almonds.

“Eat cicadas?” Swafford exclaimed. “I think that’s really disgusting. I guess if they were dunked in a ton of chocolate I’d eat them, but other than that I’d steer clear of them.”