The magicicada emerges for a few weeks of chirping, mating and death

UNDER the woodlands and back yards of northern Illinois, more than a trillion grubs have woken from 17 years of underground slumber. Over the past month, the periodical cicadas of Brood XIII, native to the area, have crawled up roots, through the earth's surface and onto tree trunks everywhere, to moult and spread wings. Carl Strang, a naturalist with DuPage county, says a single acre can produce 1.5m of them. Within weeks, every one of these bugs will have dropped dead. Till then the males fly in biblical swarms among the treetops, serenading the fair sex. After much mating, females sow eggs among the twigs. Their young will repeat this dance in June 2024.

Locals call them “locusts” but the Magicicada species of North America are as harmless as can be. Having fed on root sap during their underground life, mature cicadas have no need to eat and indeed no mouths. With no bite, sting or poison, they are gentle, even helpless.

The cicada is also tasty to fellow animals—which is precisely the point of its extraordinary life-cycle. Evolutionary biologists call this a strategy of “predator satiation”: without natural defences, the cicada in its billions allows every other bug, bird, chipmunk and pet dog in sight to gorge itself silly. When every predator has been sated, only a fraction of the brood has been lost. The rest are free to idle through a brief coda to their long subterranean lives. They spend it in sunshine, music and insect love.

There are 12 broods of 17-year cicadas scattered around the Midwestern and eastern United States, and three broods on a 13-year cycle. It is no coincidence that the span of each brood's cycle is a prime number of years. If a brood were to emerge in cycles divisible by a smaller number, then local predators could reap rewards by synchronising their own shorter cycles with one of the divisors.

In Provence, the locals admire the joyful song of their annual cicada, la cigale. The more adventurous Illinoisans enjoy eating its periodical cousin. Baked, battered, sautéed and occasionally raw, cicadas feed a fair few humans in these parts. They are mildly crunchy, with a woody flavour and notes of almond, or potato. Were they marketed as crevettes du bois, they might almost find a future among local slow-food connoisseurs. But once every 17 years is perhaps too slow, even for the most patient of Midwestern mankind.

izvor