Low-flying planes will soon spray to disrupt invasive spongy moth mating

The Minnesota Department of Agriculture will treat 24 sites across Northern Minnesota to slow the spread of spongy moth.

These sites are in Aitkin, Carlton, Itasca, Pine and St. Louis counties.

Spongy moths are one of the country's most destructive tree pests, causing millions of dollars in damage to eastern forests, according to the state. As caterpillars, the invasive species can feed on more than 300 tree species — including some of Minnesota's most common trees — and they can defoliate large sections of forest in large numbers.

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Minnesota Department of Natural Resources

Officials will likely conduct management activities from the air as early as 6:30 a.m. and throughout the day for July 16-22. The dates may change depending on weather conditions in the designated areas.

Low-flying yellow planes will disperse a nontoxic, waxy, food-grade substance to disrupt the moths' mating. The substance contains pheromones specific to spongy moths that confuse the male moths. This makes it difficult for them to find females, reducing mating success.

The agriculture department reported the product is not harmful to humans, animals, birds or other insects, and it will help protect forest health, property values and the tourism industry.

The specific treatment areas, which cover a combined 83,760 acres, can be found on the state's interactive map, where residents can also sign up for text or email updates. The latest information about dates and times can be found by calling the MDA's Report a Pest Info Line at 1-888-545-6684.

Oak, poplar, birch and willow trees are some of the pests' preferred hosts. The moths spread slowly on their own, but people can unintentionally spread them to new areas by transporting firewood or other materials carrying the moths' eggs.

Local News

Funding delays nix treatment, prompt quarantine for invasive moth

Chelsey Perkins

The MN Department of Agriculture is aiming to contain the spongy moth near Grand Rapids through quarantine, since federal funds did not come in time for effective treatment.

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Other spongy moth treatments have been delayed or cut due to changes in federal funding.

An emergency quarantine began for a portion of northern Grand Rapids on May 1. The temporary quarantine restricts the movement of woody material and requires self-inspection of items kept outdoors that are being moved out of the quarantined area. The quarantine ends June 15, 2026.

More information can be found on the MDA's website.