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The Minnesota Department of Agriculture (MDA) is placing spongy moth-infested areas in Coon Rapids, Grand Rapids, and Winona under quarantine beginning May 1. A portion of each city will be quarantined, which limits the movement of woody material out of the area.

A detailed quarantine map of each area is available on the MDA website. These quarantines will be in effect from May 1, 2025, to June 15, 2026.

What does the temporary quarantine do?

• The quarantine restricts 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 quarantine requires 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. Residents should look for spongy moth egg masses which are tan, fuzzy masses the size of a quarter. They should scrape the egg masses off the item or leave the item where it is.

High levels of spongy moths were discovered in Coon Rapids and Grand Rapids during the MDA’s 2024 annual spongy moth survey. The spongy moth-infested area in Winona was reported to the MDA by employees at a city campground. 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. However, federal funding delays and uncertainties forced the MDA to cancel operations in these locations.

Spongy moths have caused millions of dollars in damage to forests in across eastern United States. 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.

To provide more information, the MDA will be hosting two informational meetings.

The MDA will be ramping up survey efforts in these areas and residents will likely notice traps placed on trees in many places. 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 1-888-545-6684.

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Media Contact
Brittany Raveill, MDA Communications
651-201-6131
Brittany.Raveill@state.mn.us