There are two common types of cicadas in Illinois, the dog day or annual cicada and the periodical cicada. Annual cicadas make their emergence yearly during the heat of summer, but now is the time for the periodical cicadas to start making their emergence. Luckily, here in northern Illinois we will not have an emergence of the periodical cicada this year. In Southern Illinois, the periodical cicada makes it emergence every 13 years, but here in the northern half of the state, they emerge every 17 years.
This year the Iowan Brood of 17 year cicadas will make their noisy appearance in western Illinois, Missouri, and southeastern Iowa. They are forecasted to emerge in Adams, Brown, Cass, Fulton, Hancock, Henderson, Knox, McDonough, Peoria, Pike, Schuyler and Warren counties in Illinois. The species of cicadas are divided into broods, referring to the year and geographical area where they emerge. Some broods are small and cover a limited area. Others are very large and emerge across many states at about the same time. There is a brood emerging somewhere every year.
The northern Illinois brood, which will emerge in late May 2024, has a reputation for the largest emergence of cicadas known anywhere. We'll also have the emergence of the Northern Illinois Sub-Brood in 2020 which will some emergence as well. See a map of emergences here: http://web.extension.illinois.edu/cicadas/13or17year.html.
Cicadas don't cause much damage besides the nuisance of the loud mating singing that the males create to attract females. Much like the annual cicadas, periodical adult males will 'sing' from late morning through early afternoon for five or six weeks after hatching These males can produce a call in excess of 120 decibels at close range, which is approaching the pain threshold of the human ear.
The periodical cicada female does use her ovipositor to make a slit in small twigs of trees. The female then lays her eggs in these slits. The eggs hatch and the nymphs fall to the ground and tunnel down through the soil to feed on sap in a root until they emerge 13 or 17 years later. Although their feeding on the tree's roots for 13 or 17 years has an impact on the growth of the tree, they do not cause enough damage to justify any control measures. The egg-laying slit made in the twig may cause the twig to dry and break off. This damage, too, is not harmful enough on an established tree to justify trying to control these insects. However, small transplanted trees, particularly fruit trees, commonly have a trunk diameter small enough that egg slits made in the trunk, may result in the tree snapping off.
Check out the Cicadas in Illinois website for information on just about anything you'd like to know about cicadas: http://web.extension.illinois.edu/cicadas/