Apr 30, 2024 - News

Cicadas plot their Music City comeback

Data: USDA and University of Connecticut; Graphic: Jared Whalen, Will Chase and Kavya Beheraj/Axios

They're coming. Any day now, billions of cicadas are expected to begin crawling, swooping and screeching their way through Middle Tennessee.

Why it matters: The swarm, known as Brood XIX or the Great Southern Brood, has been lying in wait underground for 13 years. When they arrive, experts say, they could outnumber Nashvillians by more than 202,000 to one.

What he's saying: "They come out in really massive numbers — sometimes upwards of a million per acre," Belmont University biology professor Matt Heard tells Axios.

  • "It's a really great evolutionary strategy for avoiding predators. We often call it 'predator swamping,'" he says.
  • "There's so many that they can't all get eaten and they have an increased likelihood of being able to breed."

How it works: For the past 13 years, so-called periodical cicadas have lived under the ground feasting on deciduous tree roots, waiting to emerge to find a mate and lay eggs in wooded areas.

  • The nymphs hatch and fall to the ground, where they burrow to begin the cycle anew.

State of play: The cicadas emerge based on ground temperature, with warmer areas up first. They've already been spotted in South Carolina.

  • The warm forecast in Nashville should lure them out soon.

Yes, but: Heard says the surge of new construction in Nashville might affect the number of cicadas in some parts of town, since development can upend soil and disrupt their habitat.

Zoom out: The emergence of Brood XIX will coincide with the arrival of Brood XIII to our north. Brood XIII is on a 17-year cycle and hasn't overlapped with the Great Southern Brood since Thomas Jefferson was president.

The intrigue: A relatively small portion of the red-eyed Brood XIX are expected to surface with a fungus that turns them into hypersexual, frantically mating zombies that spread the fungus like an STD, CBS News reports.

  • Oh, and it also makes their butts and genitals fall off. Really.
  • Heard plans to collect specimens to study how prevalent the fungus is among the brood. (Estimates put it at 5%-10%, he says.)

The big picture: Cicadas might not be the most popular members of the animal kingdom due to their loud buzz and tendency to fly in people's faces, but they are an ecological marvel, Heard says.

  • "They're actually very beneficial for the environment," he says, noting that they are a good food source for bugs and other animals.
  • "When they die, they provide a ton of nutrients back to the soil."
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