February 16, 2023

The Minnesota Department of Agriculture (MDA) and partner organizations are proposing to treat spongy moth (Lymantria dispar) infestations this summer at four sites in the northeastern part of the state.

Spongy moths are ranked among America’s most destructive tree pests. The insect has caused millions of dollars in damage to forests as it has spread from New England westward in recent decades. Spongy moth caterpillars can defoliate large sections of forest. This pest is found in most of Wisconsin and is now establishing itself in northeastern Minnesota.

“The spongy moth is a serious threat to our timber, nursery, and tourism industries, and the insect can be a public nuisance during major outbreaks,” said Kimberly Thielen Cremers, manager of the Plant Pest Regulatory and Mitigation Section. “We need to slow the insect’s spread into Minnesota to protect our natural resources.”

The MDA monitors for spongy moth each year, surveying for start-up infestations. When an infestation is found, the department conducts aerial treatments and targets the infestation before it can spread.

There are four proposed treatment areas covering approximately 27,000 acres in St. Louis and Carlton counties. Two areas cover parts of the cities of Duluth, Hermantown, and Proctor; these areas total approximately 9,700 acres. A third area covers Midway Township and is roughly 3,000 acres. The fourth area is in Carlton County near Holyoke and is approximately 14,000. Residents can view an interactive map on the MDA website to determine if they’re located within one of the proposed blocks.

The treatments will be conducted in mid-July, depending on insect development and weather.

Residents in proposed treatment areas are invited to two virtual informational meetings on Thursday, March 9 at 10 a.m. or 6:30 p.m. to learn more about the insect and the treatment methods. To register, go to www.mda.state.mn.us/smtreatments.

There will also be an opportunity to attend an in-person open house meeting hosted by the MDA:
Tuesday, March 7
6-8 p.m.
Duluth City Hall, Room 330
411 W 1st Street, Duluth, MN

Residents in each of the four proposed treatment areas will also be receiving a postcard with more information. Citizens can also find info on spongy moth treatments, sign-up for text or email notifications, and proposed treatment area maps at www.mda.state.mn.us/smtreatments.

Comments on any of the proposed treatments are being accepted through March 30, 2023. Comments should be submitted in writing via mail or email to:
Kimberly Thielen Cremers
Minnesota Department of Agriculture
625 Robert Street North
St. Paul, MN 55155

The MDA has successfully treated dozens of spongy moth infestations across eastern Minnesota from Grand Portage to the Twin Cities to Houston County. These successful treatments help postpone the full-scale invasion of spongy moth. They also save local communities and homeowners money and protect the health of the state’s urban and natural forests.


Media Contact
Allen Sommerfeld, MDA Communications