2 broods of cicadas set to emerge: 2024 map of where they'll be spotted

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The buzzing bugs are back, and this time, with a droning double feature.

Two broods, the 17-year "Northern Illinois Brood" (Brood XIII) and the 13-year "Great Southern Brood" (Brood XIX), are emerging during the same year for the first time in 221 years, spanning as far east as North Carolina and as far west as Missouri, as far south as Louisiana and as far north as Wisconsin — although Michigan won't be as bug-bombarded as other states.

While Brood XIII crosses into south Michigan, Hannah Burrack, professor and chair of the Department of Entomology at Michigan State University, says that we shouldn't expect to see a ton of cicadas on our side of the state line.

"The populations in Michigan didn’t emerge in 2007, so it’s unlikely that they will be active this year," Burrack said. "It’s possible, but I wouldn’t get our hopes up."

Regardless, here's what you might want to know about cicadas ahead of the 2024 double emergence.

What are cicadas exactly and why should I care?

Cicadas are insects found in North America, consisting of more than 3,000 species. They're between an inch and two inches long, with small bristle-like antennae and four clear wings, and some of them — seven species to be exact — only come up from underground in groups known as "broods" once every 13 or 17 years to reproduce.

Between April and May, Brood XIII and Brood XIX are going to emerge and take over the eastern U.S. together for the first time in 221 years, but Brood X, which emerged in 2021, is the only brood with much presence in Michigan.
Between April and May, Brood XIII and Brood XIX are going to emerge and take over the eastern U.S. together for the first time in 221 years, but Brood X, which emerged in 2021, is the only brood with much presence in Michigan.

Those are "periodic" cicadas, as opposed to the annual or non-periodic cicadas that have a one-year life cycle that's finished with a trip to the surface in late summer.

Scientists still aren't sure why periodic cicadas emerge every 13 or 17 years in broods, but they theorize that it's an evolutionary adaptation to avoid being preyed upon; not only will predators be overwhelmed when millions of cicadas breach aboveground at once, they'll get their fill of prey quickly and plenty of cicadas will be left over to produce another generation of cicadas.

In the duration of those 13 or 17 years, immature cicadas feed on sap from the roots of perennial plants and wait for the day they can emerge as adults.

When will the cicadas emerge?

Research has shown that cicadas are triggered to emerge when soil temperatures reach 64 degrees Fahrenheit or higher, leading scientists to estimate that the insects will begin popping out sometime in late April or May.

The cicadas won't stick around for too long, though. They'll come out, drone on a bit in search of a mate, lay eggs if they're female, and about a month after emerging, they'll die.

Are cicadas dangerous?

Cicadas are virtually harmless. They don't bite or sting and they don't feed on animals or plants — other than the fluids they suck out of woody shrubs and trees.

The only point of concern that Burrack brings up is if you live in a place where cicadas are expected to emerge and have just planted baby shrubs or trees because female cicadas usually target twigs or thin branches to deposit their eggs. In egg masses, this can damage the young plant, so you can wrap the plant in garden cloth or row cover fabric to shield them from female cicadas.

How are this year's cicadas different than the cicadas in 2021?

In 2021, 17-year Brood X or "The Great Eastern Brood" invaded the eastern U.S., in states like Pennsylvania, Virginia, Tennessee, Indiana and more, including parts of southeast Michigan. But even then, the numbers were lacking compared to previous emergences, relieving those with entomophobia and disappointing entomologists.

"Broods change in size and geographic range from emergence to emergence primarily because of human development. They need tree and shrub hosts that are present for their whole life cycle, so if wooded areas are cleared in the years between emergences, those populations will be reduced or potentially eliminated entirely," Burrack said.

Broods XIX and XIII: Check out the 2024 cicada map

This year, the emergence of Brood XIII and Brood XIX at the same time creates a much larger cicada span. Their reach is expected to span across 17 states to be exact, with some overlap of the two broods in Illinois and Indiana. But once again, even less are expected in Michigan in comparison with 2021, as Burrack confirms that Brood X is the only group with much presence in Michigan.

If they have wings, will they fly into Michigan?

No, answered Burrack.

"Periodic cicadas are thought to be pretty lousy fliers and usually stay near the area they emerge in," she said. "Populations may move incrementally north if winters become warmer, but that will likely take a long time — 100s of years — and would require sufficient wooded areas to support them."

More: Cicadas emerging after 17 years pee together like rain (freep.com)

What if I want to see this year's emergence?

If you're an entomophile hoping to witness this once-in-221-year event, Burrack recommends you drive just a bit southwest to our neighbors in the two-brood overlap areas.

"Folks will have the best luck heading to Indiana and Illinois if they are interested in seeing Brood XIII," she said.

This article originally appeared on Detroit Free Press: When will cicadas emerge? See 2024 map for Broods XIX, XIII