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Gypsy moths spreading into Minnesota

While gypsy moths have been identified in Hennepin County and along the North Shore, the Minnesota Department of Natural Resources said this week that the species has not yet infested the Bemidji area.

Gypsy moths are ranked among Minnesota's most destructive tree pests -- while in the caterpillar stage of their lives, they can defoliate entire sections of forest. They are especially fond of oak, poplar, birch and willow trees.

A gypsy moth caterpillar is identifiable by the five pairs of blue dots behind its head and the six pairs of red dots along its back.

Gypsy moths are not native to Minnesota, or even North America. They have spread from New England, making their way further west since the 1990s. They already are common in Wisconsin.

"Ranked as America's single most destructive pest of trees and shrubs, it was brought to Massachusetts from Europe in 1869 as part of a failed attempt to breed a hardier silk worm," according to the Minnesota Department of Agriculture's Web site. "The insect escaped and headed for the trees with disastrous effects."

The MDA now is launching its 2007 trapping program, which will allow the MDA to determine if eradication efforts are needed. Most often, eradication is done by spreading natural soil bacteria that only kills certain butterflies and moths.

There are some natural gypsy moth predators, such as footed mice and sapsuckers, but they are not always in locations where gypsy moths are found, according to the DNR.

The MDA utilizes small, tent-shaped traps with a sticky interior to capture the pests. Males are drawn to the traps, which are stapled or tied to trees and poles, due to a pheromone that mimics a female's hormones. Once inside, the males are caught in the sticky substance. In the fall, workers remove the traps and count the moths inside -- if there is a significant number, the MDA will move to eradicate them.

Mike Carroll, the regional director of the DNR in Bemidji, said that even if a male is captured in a trap, officials must confirm them in three of their four life stages -- egg, caterpillar, pupae and adult, or moth.

"That's a key point," he said, explaining that just finding a male does not mean they have infested the area.

Also, he said, there must be signs of defoliation caused by gypsy moths.

Lucia Hunt with the Gypsy Month Unit of the MDA said about 20,000 traps currently are being placed along the eastern edge of Minnesota and the Interstate 94 corridor from Wisconsin to North Dakota.

Gypsy moths eventually will become an established species in Minnesota, according to DNR's Web site, but controlling their population now can minimize and delay the damage they cause.

Hunt said residents, especially campers, can help control the gypsy moth population in Minnesota.

Female gypsy moths, who cannot fly, deposit their eggs on objects near trees on which they were feeding as caterpillars.

Because of this, Hunt said, people who are traveling, and especially camping, in infested areas should carefully check their supplies and vehicles for hitchhikers or eggs.

"And don't bring firewood back with you," she said.

Firewood, she explained, should be burned within a 50-mile radius of where it is found or purchased.

"It helps control a number of forest pests, not just gypsy moths," Hunt said.

The MDA's Web site offers a few tips on identifying gypsy moths:

-- If you see a white flying moth, it is not a gypsy moth. While females are cream-colored, they cannot fly.

-- If you see silk tents or webs in the branches of trees, it is not gypsy moths. Newly-hatched gypsy moth caterpillars produce a thin silken thread, but do not have a central nest.

-- If you find just one caterpillar, it is not likely a gypsy moth; gypsy moth caterpillars usually are in the hundreds at one time.

-- If you find a moth in your home, it is not likely a gypsy moth.