Experts say the piercing mating call of the 17-year cicadas, which have taken parts of the Chicago area by storm, could cause damage to the ears of humans.

Some areas thick with the periodical insects can experience mating calls in excess of 90 decibels -- about as loud as a bulldozer -- and that sound can cause physical and psychological strain in humans, the Chicago Tribune reported Friday.

Billy Martin, a hearing scientist at Oregon Health and Science University and director of Dangerous Decibels, a public health campaign designed to reduce noise-induced hearing loss, said long-term exposure to the sound can cause hearing loss, anxiety, aggravation and high blood pressure.

"Loud sound is very stressful, especially if the sound is annoying and loud," Martin said. "It's the double whammy and cicadas, for the most part, are both."

John Cooley, a University of Connecticut entomologist, said hot sunny days like Thursday encourage the cicadas.

"If you have a period of cool, rainy days like this and you get a hot sunny day, they'll just come roaring out," he said.

Copyright 2007 by United Press International