Chicago officials issued an advisory Friday about the cicadas’ upcoming emergence, alerting residents of what to expect.
The spring emergence is expected to mark a rare and historic moment as two broods emerge in parts of the United States for the first time in 221 years. And with Brood XIII and Brood XIX poised to emerge simultaneously, Illinois will be in a unique position to witness this unique emergence.
Chicago officials said the emergence was expected between late April and early June, but the city may not see as much of an impact.
“Cicadas are generally more prevalent in areas undisturbed by new construction, public works or other soil excavations,” the Department of Streets and Sanitation (DSS) Bureau of Forestry said in the notice. “As these types of locations are limited to Chicago, the Bureau of Forestry does not expect significant tree damage.”
The city said areas that could be impacted are neighborhoods primarily home to older homes.
“New construction and excavation of the soil destroys cicada larvae, and several 17-year cycles are required for them to recover. Therefore, communities with older homes may have more cicadas because the soil with insect larvae was largely intact,” the notice states.
The department stressed that cicadas are “mostly harmless” but can impact the growth of young trees, but the city still plans to continue planting trees.
“The Bureau of Forestry will continue to plant trees approximately 2 ½” to 3″ in diameter, while cautioning that in areas with higher cicada populations, trees less than 2″ in diameter may experience damage. notable damage affecting future growth,” the department said. “The damage is caused by the insect using its ovipositor (laying appendage) to deposit its eggs in tree branches and the injuries often appear as small clusters of browned leaves as the small twigs die. Most trees recover quickly from this type of damage. ”
The Morton Arboretum recommended “delaying spring planting of very young trees or using protective netting for these trees until after the event.”
Cicadas typically emerge when the ground begins to warm in spring and early summer.
For the Chicago area, Brood XIII will be most visible in parts of northern Illinois and Indiana, and perhaps even Wisconsin and Ohio, in late May 2024, said Dr. Gene Kritsky, dean of behavioral and natural sciences at Mount St. Joseph University in Cincinnati said in a 2023 press release.
According to an article from the University of Illinois Urbana-Champaign Extension, emergence of the northern Illinois brood typically occurs in May and June and lasts about four weeks.
“Adult cicadas will be active until mid-to-late June, but you will see evidence of them long after they are gone, including their wings, molts and decomposing bodies,” Dana said.
Here’s a map of what to expect in Illinois, according to data from the USDA Forest Service.
“Most of the state of Illinois will experience periodic emergence of cicadas in 2024,” the University of Illinois reported.
The northern Illinois brood itself is enormous, with a reputation for “the largest cicada emergence in the world,” according to the University of Illinois.
In 1956, entomologists reported as many as 311 “emergence holes” per square meter in a forested floodplain near Chicago, which experts said translates to 1.5 million cicadas per acre, according to the University of Illinois.
“When cicadas begin to die and fall from trees later in the spring, they are in large numbers on the ground and the odor of their decaying bodies is noticeable,” reports the University of Illinois. “In 1990, Chicagoans had to use snow shovels to clear their sidewalks of dead cicadas.”
NBC Chicago
