Trapping data collected by the Wisconsin Department of Agriculture, Trade and Consumer Protection (DATCP) indicates that the spongy moth, an invasive insect from Europe that feeds on the leaves of more than 300 tree species, is now established in La Crosse County. As a result, this county has been placed under state and federal spongy moth quarantine, joining most of eastern and central Wisconsin already considered to be infested with the pest.
This is the first time since 2023 that a new county has been added to the quarantine, and 54 of Wisconsin’s 72 counties are now quarantined for spongy moth. The quarantine has the greatest impact on plant nurseries, Christmas tree growers, loggers, and sawmills because of movement restrictions and inspection requirements. These types of businesses must enter into a compliance agreement with state or federal plant regulatory officials certifying that their nursery stock and wood products are free of spongy moth before they can be transported into non-quarantined counties or states.
People living in a quarantine county must be careful when moving outdoor items. Because spongy moths can lay egg masses on nearly anything kept outside, and a single egg mass can contain up to a thousand eggs, there is a risk of spreading spongy moth when transporting items like patio furniture, campers, boat trailers, or firewood.
“If you are going camping or heading to your cabin, check your gear before leaving to ensure you aren’t carrying spongy moth egg masses or caterpillars with you,” said Brian Kuhn, director of the Plant Industry Bureau at DATCP. “This is very important if you are headed to areas in far western Wisconsin, Minnesota, or Iowa where the spongy moth population is low. A county can be infested without showing immediate damage and it is important for everyone to practice diligence in order to keep this invasive pest from damaging more of our state’s plants and forests.”
It is important to remember the quarantine restrictions even though you may not notice widespread tree damage in the quarantine area. Spongy moth is an invasive pest that has been spreading westward since its introduction to North America. Spongy moth caterpillars feed on the leaves of many species of trees and shrubs, especially oaks, and can cause severe leaf loss when feeding in large numbers.
For more information, contact Northern Field Services Unit Supervisor Jennifer Oestreich at (715) 701-1375 or jennifer.oestreich@wisconsin.gov.
