A 17 years cyclic invasion

Jun 11, 2007 11:12 GMT  ·  By

The character of La Fontaine's fable has turned into a grotesque American nightmare.

One that comes at each 17 years, and which could be gone by the beginning of July.

In the Illinois area, chorus of cicadas throb in the oak trees, brain-piercingly loud. "It's dreadful. (...) it's the noise. By midday, I get a headache. You can't hear yourself talk," said Mary Coen, 62, of Downers Grove.

The insects have emerged by the billions, molted and now they are emitting mating calls that are so loud that they can be heard in speeding cars over the engine, tire and wind noise.

In the cicadas areas, the noise can overcome 90 decibels, about as loud as a bulldozer, comparable to lawn mowers or peaks on hot days. "If you have a period of cool, rainy days like this and you get a hot sunny day, they'll just come roaring out," said John Cooley, a University of Connecticut entomologist.

The noise reaches its peak in the middle of the day, so nighttime is relatively quiet. The males try to attract females with their calls four or five days after they go out from the ground and molt. The calls are emitted by a pair of ribbed membranes in their abdomen (tymbals), turned on by means of a series of powerful muscles.

There are also annual cicadas, that emit ringing drones that are similar to the periodicals', only that the latter come out in overwhelming numbers, inducing this effect. "Exposure to 91 decibels of sound for two hours, or 94 decibels for one hour, could begin to cause some permanent hearing damage," said Billy Martin, a hearing scientist at Oregon Health & Science University and director of Dangerous Decibels, a public health campaign designed to reduce noise-induced hearing loss.

"Such noise also could cause psychological strain. Powerful, high-pitched, abrasive sounds, such as cicadas, are like fingernails on the chalkboard, and they may cause anxiety, aggravation and high-blood pressure. Loud sound is very stressful, especially if the sound is annoying and loud. It's the double whammy and cicadas, for the most part, are both." said Martin. "People tell me they can hear it through the phone. They ask what the buzzing is and I tell them it's the cicadas. It's distracting. It's like a constant buzz.", said Wilmette resident Mary White, 41.

In many places, the lawns are covered in cicadas (alive, dead and molted shells), the fluttering bugs dive-bomb into anyone passing by and the stench of rotting cicada corpses hangs in the air.