A map of where they emerge – NBC Chicago

Cicadas are officially emerging from the ground in several parts of the Chicago area as the start of a historic emergence begins. But where can you expect them most?

The emergence of Brood XIII and Brood XIX, which have not germinated simultaneously in over two centuries, began earlier than average in Illinois.

“The periodical cicadas have been emerging for the last week and a half,” Stephanie Adams, a plant pathologist at the Morton Arboretum in Lisle, said Tuesday of Brood XII, which will soon spread throughout the Chicago area. “We found them both here in our landscape and also in our eastern woods.”

According to Adams, the emergence of the first cicadas occurs about two weeks earlier than the historical average. This will continue to be sporadic, 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.

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.

“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.”

The Northern Illinois Brood, or Brood XIII, will be most visible in parts of northern Illinois and Indiana, and perhaps even in Wisconsin, Iowa and parts of Ohio . This brood will be the largest in the Chicago area for the next emergence.

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.”

Emergence is expected to last until mid-June.

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

“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.”