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Naturalists expect the invasion to begin as early as today and certainly before the week's end.
In swathes of the Midwest, from northern Illinois to parts of Wisconsin, Michigan and Indiana, Brood XIII will emerge from the earth to fill the air with a sound as deafening and grating as a petrol-powered chainsaw.
It is a remarkable rite that happens only in the eastern half of North America. Brood XIII is the name given to billions of 'periodical cicadas' which have been dormant in the ground for 17 years and this week will answer the call to surface and mate, noisily.
The clatter of the common annual cicada is as much a part of summer in the US as lemonade and baseball. But periodical cicadas are different because of their extended periods of dormancy. And when they surface they do so in overwhelming numbers.
Any day now, the nymphs of Brood XIII will burst from the soil, scale the nearest vertical surface, usually a tree trunk, and shed their skins to sprout the adult cicada's wings. The last such mass emergence was in 2004. Those cicadas belonged to Brood X.
With as many as 1.5 million of the red-eyed insects crowding a single acre, they are hard to miss. Fortunately they do little damage other than rattling the ear-drums and stripping smaller shrubs. It is usually over within 30 days when the adults die. By then the mating is done and the females will have laid their eggs in twigs and leaves.
A little later the eggs will hatch and the new nymphs will migrate down back into the soil where they will remain, sucking sap from tree roots, until it is their time to resurface. Brood XIII will not be back until 2024.
This year's onslaught is coming a week or two earlier than usual - another sign, scientists say, of higher temperatures thanks to carbon emissions.
"Global warming [is] ... just there, and things will start to change as a result of that," confirmed Dan Summers, an authority on cicadas at the Field Museum of Chicago.
Midwesterners, meanwhile, can do nothing about the intrusion aside from covering their ears.
- INDEPENDENT
