Temporary Quarantine for Spongy Moths in three cities including Grand Rapids

A quarantine has been placed in three cities with spongy moth-infested areas. The Minnesota Department of Agriculture (MDA) announced Thursday it will place Grand Rapids in Itasca County, and the cities of Coon Rapids and Winona under quarantine beginning May 1st.

The quarantine means that the public will have limited access and movement of woody material out of the area. Portions of the each city will be under the quarantine. A detailed map of each city is available on the MDA website. These quarantines will be in effect from May 1, 2025, to June 15, 2026.

The MDA will be hosting two informational meetings. One in person, on Wednesday, April 30th, 4:30-6:30pm. Another on Tuesday, April 29th, 12pm-1pm, on Microsoft Teams. 

Why the quarantine?

These quarantines will help by restricting the movement of trees, branches, and woody material, including firewood, out of the area. Trees may be pruned, but all branches and woody material must stay on the property (even if limbs are chipped spongy moth eggs are still viable).

The MDA also asks for self-inspection of any equipment, household items, or vehicles that are sitting outside in the quarantined area and are being moved out of the quarantine. This includes items such as wood pallets, patio furniture, grills, as well as campers, and boats. The egg masses are tan, fuzzy masses the size of a quarter.

High levels of spongy moths were discovered in Coon Rapids and Grand Rapids during the MDA’s 2024 annual survey. The three areas were scheduled to be aerially managed this spring with Btk (Bacillus thuringiensis var. kurstaki), an insecticide used to kill spongy moth caterpillars and control isolated infestations. These operations ran into funding delays and uncertainties which prevented their management.

The moths are common in Wisconsin and are now threatening Minnesota. If present in large numbers, spongy moth caterpillars can defoliate large sections of urban and natural forests. Spongy moth feeds on over 300 different species of trees and shrubs, including many of Minnesota’s most common trees such as oak, aspen, basswood, and birch.

Residents are also asked to be on the lookout for any signs of spongy moths in the area. If you suspect a spongy moth infestation in your area, use the MDA’s online Report a Pest service, email reportapest@state.mn.us or call 1-888-565-6684.