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Gypsy moth larvae

Gypsy moth traps to be set this month

By Sarah Kirchner | Albert Lea Tribune

Published Saturday, June 7, 2008

The Minnesota Department of Agriculture will be setting gypsy moth traps this month to monitor the spread of the damaging and invasive species.

“They’re always a threat,” said Integrated Pest Management Specialist Fritz Breitenbach with the University of Minnesota Extension. Breitenbach is not an expert on the species.

Around Minnesota, the Department of Agriculture will set almost 17,000 gypsy moth traps as part of its annual program to monitor the state’s forests and urban areas for infestations.

Gypsy moths are one of a series of exotic invasive species not native to North America that is wiping out or reducing many tree species. There are no known natural controls, according to the Department of Agriculture.

“We’re basically losing species out of our forests and species diversity,” said Extension Forester Mel Baughman, who helped organize one of the first gypsy moth efforts in the country in the 1980s.

Traps resemble tents on the side of tree trunks or poles. They contain a pheromone to lure male gypsy moths, which will then get stuck inside.

In the fall, workers will collect the traps and count how many moths are collected. This will indicate any infestations of concern. If an infestation is found, the Department of Agriculture will treat the area.

Tree damage is caused by the caterpillar, which eats the foliage and wastes much of the leaves, eventually killing the tree. A caterpillar can eat several square feet of leaf matter in its lifetime.

While a tree is losing foliage to the gypsy moth’s caterpillar, it is more susceptible to diseases and other pests.

Trees particularly susceptible to gypsy moths in southern Minnesota are oak, aspen, birch and basswood. The insects don’t like maple, pine or spruce, Baughman said.

The moths have spread west from New England since the 1800s. Gypsy moths are common in Wisconsin and threaten eastern Minnesota. The female moth can’t fly, it only floats on the wind and can land up to a half mile away. The male moths can fly, and that’s what the traps are hoping to catch.

Gypsy moths travel by attaching egg masses to mobile objects, such as cars or campers. In 2007, a few populations were found in Cook and Lake counties along Lake Superior. Campers who frequent northern Minnesota should be aware of egg masses attached to their vehicles when driving home.

Egg masses, which are usually laid in May or June, are tan in color, fuzzy and about the diameter of a quarter, Baughman said. If an egg mass is found, he said, people should report it to authorities such as the Department of Agriculture or a park officer.

If an official isn’t readily available, Baughman suggested scraping the mass off and putting it in a container to show someone at a later date.

Once the egg mass hatches, the caterpillar is only one-sixteenth of an inch long, hairy and black. As the caterpillar grows to 1 1/2 to 2 inches long, it has two rows of blue dots on the front and two rows of red dots on the back. The dots make it easier to identify than an adult moth, which is either white or brown, according to Baughman.

If a fully infested tree is found there are sprays available to kill the insect. However, the Department of Agriculture wants to locate initial infestations and recommends not setting personal traps.

Baughman said there are dozens of infestations in Minnesota, but treatments are done to keep them from becoming well established.

“That’s the whole reason behind the program,” Breitenbach said.

Quick facts on gypsy moths

Each female moth lays one egg mass containing 500 to 1,000 eggs, which can be laid on anything and often on objects carried by people.

Larvae are light enough to blow away with a breeze and can land up to a half mile away.

Homeowners must pay the cost to remove and replace trees weakened or killed by gypsy moths. Tree loss causes property values to decline.

Caterpillars feed on the leaves of 300 species of trees and shrubs. They prefer oak, aspen and birch. Defoliation makes trees vulnerable to disease, pests and environmental stress.

In 2007, more than 1.4 million acres of trees were stripped bare.

The first sign of gypsy moths in Minnesota was in Duluth in 1969. In 2008, six sites in Lake and Cook counties will be treated.

— Information courtesy of the Minnesota Department of Agriculture