Close Calls, But No Spotted Lanternfly In WI

Pictured: Spotted lanternfly. Photo by Eric R. Day Bugwood.org

Detection work for the spotted lanternfly has been underway in Wisconsin for the past seven years. From its initial discovery in Pennsylvania in 2014, this pest has spread to 19 other states and continues to edge closer each year.

It has been established in the Chicago area of Illinois, in several Indiana counties, and in eastern Michigan, according to the state Department of Agriculture, Trade and Consumer Protection.

While SLF has not yet been found in Wisconsin, the 2025 season brought new potential sightings and reports, as well as a U.S. Customs and Border Protection interception on a Lake Michigan barge heading to Milwaukee. The live SLF were found by CPB agriculture specialists who notified DATCP before the ship docked at the port. All of the SLF life stages were killed with insecticide, and follow-up surveys at the site found no further signs of the invasive insect. This close call underscores the importance of CBP as a “first line of defense” against invasive species and plant diseases and the risk of international ports as introduction pathways for plant pests.

In addition to surveys at the Port of Milwaukee, DATCP field staff conducted SLF visual surveys in 14 counties along the perimeter of high-risk introduction pathways (i.e., railyards, warehouses) or as follow-up to sightings reported by the public. A total of 158 visual surveys were completed, and 506 new locations of tree-of-heaven, the primary host of spotted lanternfly, were logged.

To date, no active SLF infestations have ever been found in Wisconsin. Consistent detection efforts, extensive outreach, and partnership with CPB have so far kept SLF out of the state. Growing awareness and DATCP’s preparedness offer hope that the pest’s impact will be low when it eventually arrives.

Learn more: https://datcp.wi.gov/Pages/Programs_Services/SLF.aspx