We have been hearing for months that two broods of periodical cicadas will emerge from the ground this May in central Illinois: the 13-year Brood XIX and the 17-year Brood XIII. These cicadas have been living underground, feeding on tree roots for either 13 or 17 years, depending on the brood.

Is everyone going to be affected? The short answer is “No.”

Archived records indicate that periodical cicadas are primarily found along rivers and their tributaries in central Illinois, where woodlands and forests were historically located. Away from the rivers and streams was the tree-less prairie. Cicadas are not good fliers and are observed to have flown no more than 164 feet at a time. They fly only to mate and lay eggs, so they remain close to their emergence sites.

Where will cicadas emerge?

In the area of central Illinois where I live and work, we can expect to experience the 13-year Brood XIX emerging in places near and along the Sangamon River and its major streams from Riverton east to north of Fisher, Illinois. For Decatur, the east and south sides of the city will likely be affected.

In the Springfield area, the 13-year Brood XIX will impact areas along the Sangamon River to the east and south, while the 17-year Brood XIII will emerge in the north and west.

Will cicadas cause any damage?

If you live in one of these areas where cicadas will likely emerge, consider protecting newly planted or young trees and shrubs. Female cicadas lay their eggs in grooves cut into small diameter twigs. These trigs often break off at this point, causing damage known as “flagging.” Flagging will not kill healthy, mature trees but can affect newly planted ones. 

To protect these small trees and shrubs, place netting with small openings (less than ¼”) over them and secure around the base. Insecticides are not recommended to manage periodical cicadas. Large, healthy trees can survive egg-laying with no long-term impacts. This has been happening for thousands of years. Insecticides are less effective in protecting smaller trees and shrubs from cicadas than netting.