Asian gypsy moth aerial spraying set for Saturday in South Sound

Asian gypsy moths have never established themselves in North America, and state and federal agencies want to keep it that way.

On Saturday, if it isn’t rainy or windy, the state Department of Agriculture will use an airplane to spray five South Sound areas with an organic insecticide safe to mammals, fish and birds.

A nearly 7,000-acre area will be sprayed in and around the Port of Tacoma. Another 600-plus-acre tracts will be sprayed near Gig Harbor, Kent, Nisqually and north of Lacey.

The spraying is being done because four male Asian gypsy moths were caught in separate traps at the port. Two others were caught in the Kent trap. The other traps had one each.

If done Saturday, spraying near the port will start a half hour before sunrise and last for a couple of hours, with the plane flying 160 mph at an altitude of 250 feet.

  

Because gypsy moths emerge later at higher elevations, sprayings at higher areas near the port, including Northeast Tacoma, are set for April 25, April 30 and May 5.

Sprayings north of Lacey are set for April 28, May 3 and May 7. Sprayings in Gig Harbor are set for April 29, May 4 and May 9.

“This is as tentative as tentative can be,” Agriculture Department spokesman Hector Castro said. “If it’s rainy or foggy or there’s too much wind, then there won’t be spraying.”

The pesticide being used, Btk, is a naturally occurring bacteria fatal to caterpillars when consumed. It is being applied three times to ensure it gets the insects.

Plans to spray were moved up because recent warm weather prompted gypsy moth eggs to hatch sooner than expected, Castro said.

That makes it more difficult to get the pesticide out when it would be most effective, he said.

The invasive insects, cousins to the European gypsy moths that have colonized much of New England, defoliate trees and shrubs, and can reproduce in large numbers.

Unlike their cousins, female Asian gypsy moths can fly, which increases their range. They eat evergreen and deciduous plants.

If the moths establish themselves, they could devastate Washington’s environment and hurt its economy, officials said.

“They’re really vociferous. They just eat,” Castro said. “They can do a lot of damage to urban parks and forests, and at a rate that would really cause a lot of problems for Washington state.”

The moths hadn’t been seen here since 1999, but when nine of the insects turned up in traps around South Sound last summer, officials moved to eradicate them.

The traps capture the moths when they are fully grown and beginning to mate. The pesticide has to be applied when the moths are in their caterpillar stage, and are just now hatching from their eggs.

Gypsy moths’ live about a year, Castro said. Eggs are laid in late summer or early fall and stay dormant through the winter. They hatch into caterpillars in the spring and begin to eat for two to three months before going into cocoons for about a week.

When they emerge from cocoons, they become moths for up to two weeks, just long enough to mate and lay hundreds of eggs, when the process starts again.

Officials suspect Asian gypsy moths entered the United States on container ships arriving at the Port of Tacoma.

“It’s kind of hard to find the smoking gun here,” said Paul Chaloux, national policy manager for the U.S. Department of Agriculture’s Animal and Plant Health Inspection Service.

“The simple answer is the increase in global trade, especially with our Asian trade partners,” he said. “We do know that several of our Asian trading partners have seen very high populations of Asian gypsy moths over the past few years.”

The Port of Tacoma is working with the state Agriculture Department to coordinate the pesticide spraying there, port spokeswoman Megan Anderson said.

Inspections of ships arriving at the port are done by U.S. Customs and Border Protection, the Coast Guard and the U.S. Department of Fish and Wildlife, she said.

Anderson complimented the state on how it has communicated with the port and has tried to affect as few people as possible with its treatments, praise echoed by neighborhood leaders near the port who will see spraying in their areas.

“The presenter (Castro) did an awesome job easing people’s fears that the spray might be toxic,” Eastside Neighborhood Council President Lynnette Scheidt said in an email. “He assured all it was safe. He was informative about how these types of moths hijack their way here through containers being shipped from Asia.”

John Thurlow, the co-chair of the Northeast Tacoma Neighborhood Council, lived in northern New Jersey in the 1980s, when “gypsy moths were a plague.”

“One of the things I remember from 20, 30 years ago and checked up on again is the really good track record of the pesticide Btk,” he said.

The pesticide application, organized and administered by the state, will be paid primarily by grants from the U.S. Department of Agriculture.

The agency provided $1,673,944 to eradicate the moths and the state is spending $557,981, according to state data. This includes treatment of an area near the Port of Vancouver, where one Asian gypsy moth was trapped. The Oregon Department of Agriculture will do sprayings there.

A combined $400,000 in state and federal money is being spent to place USDA-provided traps later this year, and the USDA is spending $162,939 to get European gypsy moths out of Seattle’s Capitol Hill neighborhood, where 22 were trapped.

The traps contain female pheromones, which attracts male moths, and a sticky substance that keeps the insects inside the traps once they enter, Castro said.

The state placed more than 19,000 traps throughout Western Washington last year, catching 42 moths in them.

The state treats for gypsy moths every year, though it hasn’t trapped this many before, Castro said.

“We’re treating every year to keep them from being established here, because once they’re established here, all we can do is slow them down,” he said.

The populations are not considered established because moths haven’t been trapped in multiple locations in the same area for two or more years. When that occurs, the USDA consults with state officials to determine whether the moths meet the establishment threshold.

European gypsy moths have a “host range” of 350 deciduous trees and shrubs they can eat, Chaloux said, while Asian gypsy moths can feed on about 500 plants, including evergreens.

“In Western Washington, we have a lot of host material for them,” Castro said. “It’s a huge concern that we found so many.”

This story was originally published April 13, 2016 at 5:14 PM with the headline "Asian gypsy moth aerial spraying set for Saturday in South Sound."