Four areas in or near Duluth, Cloquet, Ely and Two Harbors will be treated to fight gypsy moth infestations found in those areas last fall, the Minnesota Department of Agriculture said Monday.

Officials will conduct the treatments starting Monday and ending by June 15, with the exact dates determined by weather conditions and caterpillar development.

To eradicate the moths before they spread, officials will conduct two aerial applications, spaced seven to 10 days apart, of Bacillus thuringiensis var.kurstaki (Btk) over each of the areas, said a news release.

For the gypsy moth treatment to work, it must begin in the morning, as early as 5:15 a.m. Residents in and around treatment areas may be awakened by the noise of the low-flying airplane.

The treatment product is organic certified for food crops, the news release said. It has no known health effects for humans, pets, birds, fish, livestock, bees and other insects, 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 does not cause damage to outdoor surfaces and can be removed with soapy water.

Treatment areas include:

• Cloquet: A 460-acre area that runs north of Minnesota Highway 45 up to Pearl and State streets.

• Duluth: A 352-acre area in the Lakeside Neighborhood that begins approximately at Oneida Street on the south and North 52nd Avenue East on the east and extends northwest past Skyline Drive.

• White Iron Lake, outside of Ely: A 77-acre area on White Iron Lake near the intersections of Shady Rest Road and Big Rock Drive.

• Two Harbors: A 526-acre area that is centered on the intersection of Shoreview Road and Seventh Avenue.

According to the state agriculture department, 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. Oak, poplar, birch and willow are among their preferred hosts. The moths spread slowly on their own, but people unintentionally help them by transporting firewood or other items on which the moths have laid their eggs.