How does the emergence of cicadas take place? Experts Explain – NBC Chicago

How exactly do billions of cicadas know how to emerge from the ground at almost exactly the same time?

Historical synchronization already begins as two broods whose events appeared together in over 220 years emerge simultaneously from the earth.

Experts say this process is known as synchronization, which has been studied for centuries.

“The study of synchronization is itself rooted in physics, often considered to have originated in Dutch physicist Christiaan Huygens’s studies of pendulum clocks in the 17th century. Synchronization is now recognized as an important behavior in many fields – from technical systems such as electrical grids, to biological systems such as the firing of neurons in the brain, to other ecological phenomena such as the coordinated production of fruits by Oaks,” Jorin Graham of Northwestern University, a physics doctoral student studying network science. “Remarkably, such synchronized behavior is typically achieved without centralized planning or enforcement.”

So how does it work with cicadas?

According to Graham, each cicada counts the years underground using “annual cycles of xylem flow, a nutrient fluid found in the trees on which they feed.”

Depending on which periodic cicada they belong to, 13- or 17-year-old cicadas will then wait to emerge with the rest of their brood that same year.

But it doesn’t always work.

Graham said some cicadas, considered “stragglers,” miscount the year and emerge earlier or later than the rest of their broods. If these cicadas reproduce, their offspring then become out of sync.

The chances of this happening, however, are slim.

“The synchronization is preserved by predators, such as squirrels, which quickly consume cicadas that emerge at the wrong time,” Graham explained. “In normal emergence years, so many cicadas emerge that predators cannot eat them all, allowing the remaining cicadas to reproduce, thus sowing the seeds for the next coordinated emergence.”

This is certainly the case for the historic emergence of 2024, which will bring billions of cicadas to the surface.

The two emerging broods are Brood XIII and Brood XIX, which have not emerged together in 221 years.

“It’s like the year of Illinois,” cicada expert Catherine Dana, affiliated with the Illinois Natural History Survey, told NBC Chicago. “We’re going to see cicadas emerge across the state.”

Although signs of an emergence have been noted for weeks, the real peak in the Chicago area is expected any day now.

“Periodic cicadas will begin to emerge when the ground temperature eight inches below the ground reaches 64 degrees,” Jennifer Rydzewski, an ecologist with the DuPage County Forest Preserve District, told NBC Chicago.

That’s likely with a warm weekend in store for much of the region.

“It’s getting really close,” Rydzewski said.

The emergence began earlier than average in Illinois, but much of the region has yet to be warned about the cicada swarms and failing sounds that have triggered 911 calls in some states.

According to some experts, the emergence of the first cicadas took place about two weeks ahead of the historical average. This will continue to be sporadic, however, as soil temperature, mulch, and turf all impact cicadas differently. For example, the ground is warmer near sidewalks, so cicadas in those locations should emerge more quickly.

When cicada nymphs first emerge from the ground, they climb up to a tree or other high place and shed their shells.

Within a full year of emergence, after the insects surface, they then begin mating, which often results in the noise most associated with cicadas. DuPage Forest Preserves experts said it takes about a week after emergence before the cicadas begin mating.

Watch as district staff bring a creative twist as they take us through the fascinating life cycle of a 17-year-old cicada.

Cicadas have a lifespan of about four weeks, meaning emergence should last until at least mid-June.

Where we will see the emergence

For the Chicago area, Brood XIII will be most visible in parts of northern Illinois and Indiana, and perhaps even Wisconsin and Ohio, said Dr. Gene Kritsky, dean of behavioral sciences and natural studies at Mount St. Joseph University in Cincinnati.

The northern Illinois brood itself is enormous, with a reputation for “the largest cicada emergence in the world,” according to the University of Illinois.

Meanwhile, Brood XIX, or Great Southern Brood cicadas, have a more widespread population, covering parts of Missouri, Illinois, Louisiana, North Carolina, Virginia, and Maryland.

“Brood in Oklahoma,” reports the University of Connecticut. “Although 13-year-old cicadas are generally considered to have a southern distribution, the northernmost known record of this brood is in Chebanse, Illinois, approximately 75 miles from Chicago’s Loop.”

In most of Illinois and the Chicago area, at least one of two broods is likely to emerge, but in a narrow part of the state, both could emerge at the same time, in the same location.

“Somewhere in central Illinois, probably like around Springfield, some researchers are predicting that we might see some overlap of these two different broods,” Dana said. “It won’t be a big area. But there will probably be some mating between these two broods, which will be really exciting.”

Here’s a map of what to expect in Illinois, according to data from the USDA Forest Service.