WELLESLEY, Mass. -- Scientists in Wellesley hope 1,000 flies can help combat the damage that winter moths can do to foliage.

Winter Moth Predator Takes Flight

NewsCenter 5's Steve Lacy reported that winter moths are native to Europe and came to the Unites States years ago on shipping vessels. There are no natural winter moth predators in the United States.

Winter moths emerge from the ground in winter, but only the male is able to fly. The female lays her eggs in a tree and then dies. In spring, the eggs hatch into caterpillars that feed on the leaves. Scientists say the moths number in the trillions and can strip trees bare.

State entomologists released about 1,000 parasitic flies, known as Cyzenis albicans, that kill the winter moth caterpillars in Wellesley's Centennial Park on Friday. The fly lays its eggs on the leaves eaten by the winter moth. The eggs then hatch inside the caterpillar and the fly larvae destroy it from within.

"The flies should have no other impact on any other species other than winter months," said Joseph Elkinton, of the University of Massachusetts at Amherst.

A similar plan was successful in Nova Scotia about 50 years ago. After about eight years, the fly population took hold and the winter moth problem disappeared.

"We're basically restoring the balance that we have in Europe where the winter moths are one of many species of caterpillars that feed on trees without causing a problem," Elkinton said.