Soon the sleepers shall wake.
That sounds like the beginning of either a sermon or a horror story, but it’s not. It’s just an entomological fact.
As spring gives way to summer, trillions of cicadas will emerge from their underground burrows throughout the South and in parts of the Midwest, including Iowa. Those cicadas are part of two separate broods, Brood XIII, also known as the Northern Illinois Brood, and Brood XIX, or the Great Southern Brood as it’s known to its friends.
Red-eyed (mostly) and winged, the cicadas are often mistaken for large locusts. But like alligators and crocodiles, cicadas and locusts are different creatures even if they look the same to the untrained eye. There are more than 3,000 species of cicadas worldwide. All spend their juvenile phase — when they are known as “nymphs” — underground, safe from predators. Almost all of them emerge as adults after a year, but North America is home to a genus — Magicicada — whose members spend either 13 years or 17 years maturing underground. Brood XIII is made up of 17-year cicadas, Brood XIX of 13-year cicadas. Exactly why the Magicicada spend so long underground, and why one group waits four years longer than the other before digging its way to the surface still isn’t clear.
But like clockwork, the two broods will start to emerge as ground temperatures heat up. It will be a once-in-a-lifetime experience. Literally. The last time Brood XIII and Brood XIX emerged together was 1803. The next time will be in 2245.
The two broods will cover all or parts of 16 states, mostly in the South. There will be some overlap between the two in southern Illinois and southeastern Iowa. Some entomologists are interested in whether there will be any crossbreeding between the two broods, and if there is, what effect that might have on the offspring.
Breeding is what the emergence is all about. During their four-to-six-week life above ground, male cicadas sing — although “sing” seems entirely too generous for the loud buzzing noise they make — to attract a mate. After mating, the females lay eggs in woody plants, usually in narrow branches. The female cicada’s ovipositor has a sharp edge that they use to cut slits in the bark, into which they deposit about 10 to 20 eggs. The average female cicada will lay between 500 and 600 eggs.
At the end of the brief mating season, the adult cicadas, male and female, die.
After six to 10 weeks, the eggs will hatch and the tiny newborns will drop to the ground. They will then begin to burrow, digging down between eight and 12 inches, then settling in for the next 13 or 17 years, until they crawl to the surface and do exactly what their parents did.
Cicadas, although often annoying, are harmless to people and pets. They can be hard on saplings and delicate plants, but for the most part they are beneficial to the environment. The holes they leave behind after digging to the surface aerate the soil. The slits cut into narrow branches for eggs will eventually cause unhealthy branches to drop off trees, in a sort of accidental but helpful pruning.
Only a slice of eastern Iowa will experience this year’s emergence, but central and western Iowans jealous of their easterly neighbors getting all the noisy insect action just need to be patient. In 2031, Brood III will begin digging its way to the surface in those parts of the state. Those 17-year cicadas are also known as the Iowan Brood.
This article was originally published in Little Village’s May 2024 issue.
