Gypsy moth treatment coming to Winona County

The Minnesota Department of Agriculture (MDA) is preparing to treat approximately 1,751 acres of land in Winona County to slow the spread of a gypsy moth infestation identified last year. Officials will conduct the aerial treatment sometime between June 22 and June 29, beginning as early as 7:00 a.m. This date is dependent on weather conditions in the area leading up to the treatment date.

gypsy moth

The Minnesota Department of Agriculture will be spraying the Pine Creek area of Winona County in Minnesota to slow the spread of the gypsy moth into the state’s tree forests. (photo from hatfieldspraying.com)

To help area citizens stay informed, the MDA has set up an Arrest the Pest information line at 1-888-545-MOTH (6684). The hotline will offer the latest details about treatment date and time.

The MDA maintains a monitoring program to watch for start-up infestations. When an infestation is found, the department conducts aerial treatments of the infestation before it can spread. In 2016, the MDA found an infestation in New Hartford Township, Winona County (referred to as the Pine Creek block). (SEE MAP) Details of the area can be found at www.mda.state.mn.us/gmtreatments.

Map of treatment area in New Hartford Township, Winona County

The MDA will use a method of mating disruption involving the aerial application of a waxy, food-grade substance containing a pheromone that confuses male gypsy moths. This makes it difficult for the male gypsy moths to find females for mating, which means fewer caterpillars hatching and attacking trees next year. The 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. It is an effective tool that helps slow the spread of the insect as it moves westward across the country. Minnesota has benefited greatly from the use of mating disruption in Wisconsin and other eastern states that have kept new gypsy moth populations at bay.

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.

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Bitter winter has impact on gypsy moth in Minnesota

Minnesota Department of Ag Logo Last winter’s harsh temperatures have resulted in some positive benefits – a decline in the state’s gypsy moth population. The Minnesota Department of Agriculture (MDA) captured approximately 500 moths this year in traps around the state. That’s a major shift from last year’s count of over 71,000 moths.

“We knew going into this survey season that our numbers would be down,” said Kimberly Thielen Cremers, MDA’s Gypsy Moth Program Supervisor. “Studies have shown extended stretches of extreme cold have an impact on gypsy moth eggs as they overwinter. However, we cannot let our guard down over this invasive insect.”

In fact, University of Minnesota research has shown gypsy moth egg masses can survive a harsh winter if located below the snowline.

“While the decrease in moths is good news, we know they will bounce back quickly.” said Dr. Brian Aukema of the forest insect laboratory at the University of Minnesota. “A single surviving egg mass will produce more than 500 hungry caterpillars.”

The placement of survey traps throughout the state also affected 2014 trapping numbers.

“We placed 60 percent fewer traps in the quarantined counties of Lake and Cook this year,” said Thielen Cremers. “We know a reproducing population is established there; 90 percent of the moths caught in the state in 2013 were in those two counties, so this year we placed more traps ahead of that established population to keep on top of the spreading gypsy moth infestation.”

Gypsy moth caterpillars, which are not native to North America, eat the leaves of many trees and shrubs. Severe, repeated infestations can kill trees, especially when the trees are already stressed by drought or other factors.

A male, gypsy moth caterpillar (photo from www.constructionandtreeservices.com)

A male, gypsy moth caterpillar (photo from www.constructionandtreeservices.com)

Last winter’s harsh temperatures have resulted in some positive benefits – a decline in the state’s gypsy moth population. The Minnesota Department of Agriculture (MDA) captured approximately 500 moths this year in traps around the state. That’s a major shift from last year’s count of over 71,000 moths.

“We knew going into this survey season that our numbers would be down,” said Kimberly Thielen Cremers, MDA’s Gypsy Moth Program Supervisor. “Studies have shown extended stretches of extreme cold have an impact on gypsy moth eggs as they overwinter. However, we cannot let our guard down over this invasive insect.”

In fact, University of Minnesota research has shown gypsy moth egg masses can survive a harsh winter if located below the snowline.

“While the decrease in moths is good news, we know they will bounce back quickly.” said Dr. Brian Aukema of the forest insect laboratory at the University of Minnesota. “A single surviving egg mass will produce more than 500 hungry caterpillars.”

The placement of survey traps throughout the state also affected 2014 trapping numbers.

“We placed 60 percent fewer traps in the quarantined counties of Lake and Cook this year,” said Thielen Cremers. “We know a reproducing population is established there; 90 percent of the moths caught in the state in 2013 were in those two counties, so this year we placed more traps ahead of that established population to keep on top of the spreading gypsy moth infestation.”

An example of tree damage from gypsy moth infestations (photo from gypsymothalert.com)

An example of tree damage from gypsy moth infestations (photo from gypsymothalert.com)

Gypsy moth caterpillars, which are not native to North America, eat the leaves of many trees and shrubs. Severe, repeated infestations can kill trees, especially when the trees are already stressed by drought or other factors.

For more information on gypsy moth, go to www.mda.state.us/gypsymoth.