Forest Service looks at moths

Agency checking for infestation in the area


— The Colorado State Forest Service is hanging insect traps in Steamboat Springs to catch gypsy moths before they multiply.

"It's one of those little programs that we've been doing for a long time that no one really knows about," Forest Service entomologist David Leatherman said.

The Forest Service sets traps in every city and town in Colorado. It has hung 2,000 of the bright yellow box traps on street signs and telephone poles, one in every square mile of the communities.

The agency considers the moth one of the most destructive defoliators of trees and shrubs in the United States. It hopes to detect where any of the insects might be in Colorado before their numbers increase.

The gypsy moth, while in the caterpillar stage, feeds on tree leaves. Aspen, gamble oak, cottonwoods and various ornamental trees are its prime habitat. Since 1970, defoliation from the insect in the United States has exceeded 500,000 acres annually, according to the Colorado State Forest Service.

The moth has never been found in Steamboat Springs. If it shows up, Leatherman said a large infestation is unlikely.

"I'm pretty confident that with the trap work we could keep (an infestation) small," Leatherman said.

The traps contain pheromones to attract the moth. Since 1984, when the first gypsy moth was trapped in Colorado, mostly Front Range cities have been homes for the insect, though it has migrated past the Continental Divide. Last year one was found in Kremmling.

Traps in Grand Junction and Durango also produced moths.

The gypsy moth was introduced in the United State from Europe in 1869 by amateur entomologist E. Leopold Trouvelot in Medford, Mass. Trouvelot returned from France with a colony of the moths to cross them with silkworms, Leatherman said.

The female gypsy moth in the caterpillar stage produces more eggs than female silkworms, so Trouvelot thought he could increase production of silkworms by crossing the insects.

"The cross didn't work. Then his colony was neglected and got away," Leatherman said.

Ten years later, people in Medford noticed all their trees were dying from Trouvelot's moth colony. About 130 years later, the gypsy moth has moved into 17 states. The natural migration of the insect has kept it mainly in the East. But moths and egg masses of 750 eggs traveling with people from east to west is considered the main cause of the insect popping up in Colorado and other Western states.

The biggest concern right now is the moth moving into the tree nursery states of Michigan and Wisconsin, Leatherman explained.

Recently, officials found 35 egg masses in a bunch of blue spruce trees shipped from Michigan to a Denver suburb.

"Just do the math 750 eggs times 35 egg masses," Leatherman said.

But for the most part, the trapping program has been a success in Colorado, he said.


Use the comment form below to begin a discussion about this content.

Requires free registration

Posting comments requires a free account and verification.