Moths Threaten to Ravage Forest Lands in Northwest

TIMES STAFF WRITER

After months of anxious trapping and surveying, government officials disclosed Friday that their worst fears have been realized and the Pacific Northwest is confronted with what could be America's most devastating forest- and crop-destroying insect infestation.

In at least three locations in the Northwest, ranging from British Columbia to Oregon, government scientists said they have trapped live Asian Gypsy Moths. The U.S. Department of Agriculture issued a declaration of emergency for the region.

"It's potentially the worst insect threat we've seen in the U.S.," warned Washington state Agriculture Director Alan Pettibone.

Voracious, prolific and fast-spreading, the foliage-devouring Asian moths are the killer bees of the moth world, an exotic ugly cousin of the European Gypsy Moth that annually strips leaves off about 4 million acres of hardwood trees in the Northeast.

Officials said they fear the Asian strain of the moth may have, or probably will develop, an appetite for the evergreen conifers, the Douglas firs and pines and hemlocks that dominate Northwest forests. Unchecked, it could spread next to farmlands throughout the West.

The insect is destructive not as the winged moth but earlier in the caterpillar stage. The moth's eggs hatch into caterpillars in April and feed ravenously on green foliage until the insect pupates and emerges as the winged moth in June.

At news conferences Friday in Washington state and Oregon, state and federal officials pronounced the Northwest in a state of emergency and announced a $19-million eradication plan.

"The introduction of this exotic pest poses a major threat to forests on the North American continent," said U.S. Deputy Agriculture Secretary Ann Veneman in a prepared statement from Washington, D.C.

A preliminary study by the U.S. Forest Service said the economic and environmental losses of an uncontrolled spread of the Asian moth over the next 40 years would be nothing short of staggering:

--Timber losses would range from 15% to 25%--or $35 billion in the "best case" to $58 billion in the "worst."

--Costs of trying to suppress the insect once established could range to $821 million.

--Effects on wildlife habitat could be "profound," including the loss of valley oak forests in California and their conversion into grasslands. Oak is one of the insect's favorite foods, although it is known to feed on 600 plant species. Loss of California valley oaks would hit deer, woodpeckers and squirrels particularly hard.

--Tourism and recreation would suffer losses of up to $2 billion due to spoilage of public lands and rehabilitation requirements.

--Water supply would be affected through destruction of watershed foilage, resulting in loss of stream life.

The report warned that "there is an almost unbroken food source for the AGM (Asian Gypsy Moth) from the West Coast to the Great Plains."

Most immediately threatened are the conifer forests in the Northwest, which are economically and environmentally critical to the region, providing a major source of Western lumber and habitat for all varieties of creatures, including the threatened spotted owl. Preserving forest habitat for the owl has caused years of political and economic anguish in the region, and the threat of a moth infestation can only make matters worse.

Efforts to eradicate the moth will begin in April with the aerial spraying of a bacteria known as BT-- Bacillus thuringiensis. It produces a toxin that interferes with food digestion during the moth's caterpillar stage.

Robert Gara, professor of forest entomology at the University of Washington, a consultant to the government on the moth, said the BT bacteria has been studied extensively since 1911 and is harmless to mammals. "There is no effect whatsoever," on them he said in an interview.

Nonetheless, Washington state Health Secretary Kristine M. Gebbie advised, "It would be prudent for people susceptible to infections, such as those with leukemia, AIDS or other physician-diagnosed immune deficiencies to take certain precautions, such as staying indoors for about 30 minutes following spraying."

Initially, the BT bacteria in a solution with water is to be sprayed at three intervals over a 130,000-acre area west of Tacoma, Wash. Other spraying is planned for smaller areas around Portland, Ore. Additionally, Canadian officials said they would cooperate with action in the vicinity of Vancouver, B.C.

So far, nine moths have been trapped in the Tacoma region and one near Portland. Others have been captured near Vancouver.

Although the Asian moth, as well as its European cousin, has not been eradicated elsewhere outside the range of its natural predators, officials here said they were at least cautiously optimistic about their chances for success with a major campaign in the early stages of the infestation.

Scientists said they believed the moths arrived at the West Coast ports aboard freighters from Russia, where lights used for round-the-clock unloading of grain are believed to attract the moths onto the ships.

In addition to eradication efforts, the government attack plan calls for more careful screening of vessels arriving from the Soviet Far East.

The first sign of the Asian moths here in the Western Hemisphere appeared last fall. The recent trapping efforts found that the moths have already traveled 20 miles from dockside, a sign scientists called alarming.

Two traits in particular make the Asian moth especially feared. In the European strain of the moth, the fertile female is flightless. Her Asian sister, however, does fly. perhaps long distances, and lays more eggs, too, the scientists said.

Females lay egg masses in the autumn. The caterpillars that emerge in April are black and mottled and about 2 1/2 inches long, quite hairy, and distinguished by a row of red and blue bumps on the back.

Officials said that the lesser-feared European strain of the moth killed 12 million acres of trees in the United States in 1981, its most destructive year.

"If you are a forester or a farmer and there is one insect you could avoid dealing with, this is it," said Georg Ziegltrum, staff biologist with the Washington State Forest Protection Assn. "If the Asian moth is able to establish a population the economic impact will make the spotted owl look like peanuts."

Copyright © 2019, Los Angeles Times
EDITION: California | U.S. & World
62°