They're Hairy, They're Hungry, They're Here

HELICOPTERS FANNED OUT OVER MORE THAN 30,000 acres of the state of Washington last week in an emergency campaign to repel an airborne assault launched from across the Bering Sea. No, the ex-Soviet Union had not reconstituted itself and invaded. Instead the object of the search-and-destroy spraying mission was the Asian gypsy moth, which in its caterpillar stage is notorious for devouring the leaves of perhaps 600 varieties of trees and shrubs.

At least 35 of the pests entered the U.S. and British Columbia last fall, apparently as hitchhikers aboard a group of Russian freighters. The newly hatched caterpillars climbed up to the highest point on the ship, and were eventually blown to shore. Considered far more destructive than the European gypsy moth, which annually defoliates 4 million acres in the American Northeast, the Asian gypsy moth has decimated millions of acres in Siberia and China. Among the reasons: the Asian moths can cover 20 miles before laying their eggs. (Females of the European variety do not fly.) If the Asian gypsy moth becomes entrenched in the Pacific Northwest, the Forest Service estimates that the toll on the timber industry could run upwards of $35 billion over the next 40 years. By contrast, Washington's spray program -- which is scheduled to run about six weeks and cover 116,500 acres -- will cost $8.9 million. British Columbia has already started spraying, and Oregon has just begun.

The spray being used is not expected to hurt people, mammals or birds. It consists of naturally occurring bacteria that are lethal only to caterpillars. Some environmental groups and residents have opposed the program because the spray will eliminate butterflies and other insects as well. But officials of the state agriculture departments believe the indigenous species will quickly regenerate.