cicada

Periodical Cicada Damage Still Visible In Some Areas

Photo showing dieback discovered on red cedar branches in Beloit (Rock County) in August 2025.

Dieback discovered on red cedar branches in Beloit (Rock County) in August 2025. / Photo Credit: Wisconsin DNR

By River Mathieu, DNR Forest Health Specialist, Fitchburg
River.Mathieu@wisconsin.gov or 608-772-2758

In August, random branch dieback was observed by a Wisconsin Department of Natural Resources forester on red cedars in a 10-acre stand near Beloit in Rock County.

At first, the pattern of dieback was perplexing. Based on a photograph, the damage was first presumed to be caused by a fungal disease. Once a site visit was conducted, it was determined that the branch dieback was caused by cicada oviposition (egg-laying) damage from last year’s emergence of periodical cicadas.

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Periodical Cicada Damage Now Visible

By Bill McNee, DNR Forest Health Specialist, Oshkosh;
Bill.McNee@wisconsin.gov or 920-360-0942

Photo of Brood XIII periodical cicadas (Magicicada spp.) resting on a tree at Big Foot Beach State Park in Lake Geneva on June 12, 2024.

Brood XIII periodical cicadas (Magicicada spp.) rest on a tree at Big Foot Beach State Park in Lake Geneva on June 12, 2024.

Scattered twig death, commonly known as “flagging,” was recently observed on several trees at Big Foot Beach State Park in Walworth County, where large numbers of 17-year Brood XIII periodical cicadas (Magicicada spp.) were present. This flagging is likely present in other localized sites in southern Wisconsin that experienced high numbers of cicada emergences.

The University of Wisconsin-Madison Insect Diagnostic Lab’s Periodical Cicadas in Wisconsin webpage has more information about the periodical cicada outbreak.

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