The loudest insects

StoryImage( ‘/Images/Story//Auto-img-118054444219595.jpg’, ”, ‘The 17-year cicada – Magicicada sp., with blood-red eyes and a coal black carapace, this bulky insect appears dangerous. Don’t be fooled, cicadas don’t bite or sting, and can be safely handled. These cicagas are sometimes mistakenly called “17-year locusts,” but they are not actually related to locusts.‘);
StoryImage( ‘/Images/Story//Auto-img-118054439219686.jpg’, ”, ”);

Having remained quietly under the soil since 1990, 17-year cicadas are due for a massive emergence.

It’s not a performance that will win them any major music contracts, but 17-year cicadas have managed to gain celebrity status in recent weeks without the help of a certain American televised singing competition. They have achieved fame by simply crawling out of the earth, shaking off their youthful skins in exchange for the sturdy winged carapaces of adulthood, and then singing as loud as they could.

These impressive insects are part of brood XIII—so-named by insect scientists who have described 30 different broods of periodical cicadas scheduled to emerge in varying years throughout the Midwest.

Northern Illinois lies in the heart of this year’s cicada emergence. We may see as many as 1.5 million of these insects per acre in heavily wooded areas, according to some estimates.

Young cicadas, called “nymphs,” live underground feeding on plant juices taken from roots. Some cicada nymphs spend only a year or two under the soil, while periodical cicadas spend either 13 or 17 years, depending on the species. When it’s time to emerge, they tunnel out of the earth, latch on to a nearby plant, and moult. The shells, or exoskeletons, are left behind, often by the hundreds on a single tree.

Despite youthful years that extend well beyond most other insects, 17-year cicadas have exceptionally short adult lives. They survive only a few weeks, just long enough to mate and lay the eggs that will produce the next emergence of brood XIII, due in 2024. Males sing to attract females. And while you may hear these insects singing during any summer, this year is different because their numbers are so massive, and because 17-year cicadas like to sing all together, creating a noisy din to throw off predators.

To make their sound, they use special muscles to flex drum-like tymbals just behind their rear legs.

The noise of one cicada is literally deafening if you’re close enough to it. Sound level tests taken at a distance of 3 feet from the insect measure around 90 decibels, loud enough to cause hearing damage. In groups of hundreds or thousands, these insects create an ear-splitting buzz.

from the May 30-June 5, 2007, issue

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