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Gypsy moth treatment planned in Split Rock, Beaver Bay

Jul 15, 2018 07:16AM ● By Editor
A single-engine Air Tractor sprayer flies over Two Harbors in 2010 to spray areas to control the spread of gypsy moths. At the time, a total of 71,000 acres in Lake and Cook counties were treated with a synthetic hormone that disrupts gypsy moth mating, while another 717 acres were treated with a biological insecticide called Btk.(Clint Austin / [email protected])

From the Lake County News Chronicle - July 15, 2018

The Minnesota Department of Agriculture (MDA) is preparing to treat approximately 73,500 acres of land in the Split Rock and Beaver Bay area of Lake County to slow the spread of a gypsy moth infestation.

Officials will conduct the aerial treatment Monday, July 16, through Wednesday, July 18, beginning as early as 7 a.m. each day. The dates are dependent on weather conditions in the area leading up to the treatment date.

To help area residents stay informed, the MDA has set up an "Arrest the Pest" information line at 888-545-MOTH (6684). The hotline will offer the latest details about treatment date and time. Residents can also sign up for email or text notifications.

The MDA maintains a monitoring program to watch for start-up infestations ahead of the advancing population front moving into Minnesota from Wisconsin. When an infestation is found, the department conducts aerial treatments of the infestation before it can spread further westward.

In 2017, the MDA found an infestation along the North Shore. In cooperation with the USDA Forest Service, the department is now treating approximately 73,500 acres, including 11,000 acres of Superior National Forest land. Details of the area can be found at

The MDA will use a method of mating disruption involving the aerial application of an organically certified, waxy, food-grade substance containing pheromone that confuses male gypsy moths. This makes it difficult for the male gypsy moths to find females for mating, which means reduced mating success. The result is fewer caterpillars hatching and attacking trees next year. Application is timed just as adult moths emerge in mid-summer.

Mating disruption has been widely used for gypsy moth management in Minnesota and across the nation. Annually, close to 400,000 acres are treated with mating disruption across the United States. It is an effective tool that helps slow the spread of the insect as it moves westward across the country.

This work is being coordinated through the national "Slow the Spread of Gypsy Moth" program directed by the U.S. Forest Service. Minnesota has been part of this program since 2004. These efforts protect forest health, property values and the state's tourism industry.

Gypsy moths are among America's most destructive tree pests, having caused millions of dollars in damage to Eastern forests. If present in large numbers, gypsy moth caterpillars can defoliate large sections of forest.

About gypsy moth treatments

Spray aircraft normally arrive at urban sites at sunrise or shortly after. On average, a 640-acre block (1 square mile) takes about a half-hour to spray with a plane or two hours by helicopter. The aircraft flies over the treatment block, making sequential passes. It will be very low (about 50 feet above the treetops) and loud.

The MDA offers the following tips to residents in and around the treatment area:

• For the moth treatment to work, it must begin early in the morning. Residents may be awakened on that day by the noise of the low-flying airplane;.

• The airplane noise may spook pets, so residents may wish to keep them indoors during the treatment.

• The treatment product has no known health effects for humans, but to avoid it residents may wish to stay indoors during the treatment and keep windows closed for a half hour after application.

• The residue will not damage a vehicle's finish, but residents may wish to park vehicles indoors to avoid having to wash them after the application. Soapy water will remove any residue on outdoor items.

Source: Minnesota Department of Agriculture

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