When are cicadas coming to Chicago?
When periodical cicadas appear in Illinois this month, they will mostly be from one of two groups in a rare dual emergence — an event unseen since 1803.
The southern half of Illinois will see the appearance of Brood XIX, also known as the Great Southern Brood, which emerges every 13 years. (In addition, some early arrivals from the Mississippi Valley Brood may emerge.) The upper half of the state — including Chicago and Peoria — will see Brood XIII, the Northern Illinois Brood, on a 17-year cycle.
Here's what to know about the pending emergences:
When will cicadas emerge in Chicago?
While the broods traditionally begin arriving in May, a small contingent reportedly appeared earlier this year. The Morton Arboretum in DuPage County said on Wednesday, May 1, that a few periodical pioneers had already emerged there in late April.
The Northern Illinois Brood has a reputation for its population density. In 1990, two cycles ago, there were reports of Chicago residents using snow shovels to clear sidewalks of dead cicadas, which have a noticeable odor.
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When do cicadas come out in Illinois' other regions?
While the Great Southern Brood also traditionally emerges in May, the University of Illinois Extension said recently that cicadas had begun digging holes in the soil in Jacksonville in mid-April. Periodical cicadas begin digging holes to the surface a few weeks before they emerge. The males then begin singing their loud, buzzing mating song four or five days later.
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Which cicada brood will surface first?
Traditionally, the Great Southern Brood precedes the Northern Illinois Brood. Both groups generally begin to emerge when the soil temperature reaches about 64 degrees, the USDA Forest Service says. That typically occurs from April to early May in the southern part of their combined range and from May to early June farther north, though this year may be an exception considering the reports in DuPage County and elsewhere.
Kacie Athey, a specialty crops entomologist with the University of Illinois Extension, said Thursday, May 2, that the Great Southern Brood had already started emerging in other states. "We should start seeing them in southern Illinois very soon. If the temperatures remain high, I might expect them to be surfacing in earnest in the next week or so," she added.
This article originally appeared on Journal Star: When will cicadas emerge in Chicago?
