Plan on gypsy moths: Get them young

They may have taken over in Boston, New York and D.C., cities that have come to accept the scourge and shame of defoliation. But not here.

You might say we own the gypsy moth, the little leaf-munching miscreants that have killed millions of acres of trees along the East Coast and spread west to Minnesota -- the Midwestern front.

The battle, however, just never ends.

The moths turned up this summer in traps in Minnetonka and Richfield, part of a record count in which more than 10,000 moths were captured statewide -- nearly triple the total for 2007.

A moth infestation can kill a tree if the defoliation is repeated in successive years or if a tree is already weakened, said Lucia Hunt, gypsy moth unit supervisor for the state Department of Agriculture.

"Our goal is to keep the trees green," she said.

In Minnetonka, 60 moths were trapped this summer, and in Richfield, 19.

"Both communities are full of beautiful old oak trees, and that is the gypsy moth's favorite food," Hunt said. She estimates that each caterpillar can eat about 3 square feet of foliage in its lifespan.

In January, residents of the two cities will be invited to informational meetings about the eradication plans for next season. The department will explain how it kills the moths by spraying them from the air with a bacteria that are common in soil. The bacteria are considered harmless to people, animals and other insects.

Westward bound

Minnesota has been battling the invasive species for decades, and while gypsy moths are now common in much of Wisconsin, Minnesota has managed to beat back each invasion whenever the moths show up, the Agriculture Department says.

"The moths spread slowly on their own, but people can unintentionally help them spread by transporting firewood or other items on which the moths have laid their eggs," the department says. "Because of the way the moth deposits eggs, people camping in infested areas during prime egg-laying periods (July through mid-August) are particularly susceptible to carrying the pest home on camping gear or even in the wheel wells of their cars."

Gypsy moths were introduced to America from Europe in the 1860s in an attempt to breed a hardier silk worm, according to the department. The caterpillars escaped with disastrous effects. Now the moths feed on more than 300 species of trees and woody plants in North America, and they have gradually spread from the Eastern Seaboard westward as far as Wisconsin and into parts of Minnesota.

Battling back in Minnesota

In 2006, the Minnesota Department of Agriculture treated 48 acres in Brooklyn Park. In 2004, it treated four acres in Edina, and in 2002, 1,800 acres in Golden Valley. Such spot treatments began in the metro area in 1980, Hunt said.

After finding moths in Richfield and Minnetonka, the department set out more traps to pinpoint their location. Staff members from the city, the Agriculture Department and the Department of Natural Resources then began looking for signs of a reproducing population -- egg masses, pupa cases or shed caterpillar skins, Hunt said. Data was entered into a national database that helps the department choose management options.

By mid-October, the department will decide roughly how many acres in Richfield and Minnetonka should be sprayed for the moths next year, she said.

The department asks that residents who see the buff-colored egg masses, which are about the size of a quarter, on houses, trees or outdoor gear report them to the department's pest hot line at 651-201-MOTH (6684) in the metro area, or on the website www.mda.state.mn.us/gypsymoth.