Gypsy moth fighters think they've won two battles in Pierce County but are continuing the war against the insect the tree-wrecking insect.
The state Department of Agriculture on June 21 finished its efforts to rid a 13-acre residential area near Eatonville Highway and Hilligoss Road. Spray to kill the moths was applied four times - two in May and two in June - on trees, shrubs and other vegetation.
A second location - 43 mostly commercial acres near South Hill Mall in Puyallup - was sprayed five times between May 8 and June 28.
Officials said they believe the moths, which in its caterpillar form can destroy large stands of trees if allowed to multiply, have been killed off. But to be sure, the areas will be monitored with moth traps the rest of this summer and longer, said Mike Louisell, a spokesman for the agriculture department.
"We'll do extra trapping this summer to help determine whether any gypsy moth caterpillars escaped the treatments," Louisell said. "The sites areas will be officially declared eradicated if no gypsy moths are detected for two consecutive years."
The spray that was used is, a biological insecticide (Bacillus thuringiensis var. kurstaki or Btk), which the state has used previously on gypsy moths in other locations. Residents and businesses in the areas that were sprayed were informed of the plans for spraying at open houses hosted by the department (WSDA) in Eatonville and Puyallup in February.
"We've gotten great cooperation from residents in Eatonville and businesses at the mall," Louisell said, referring to the planning stages of the spraying and the spraying itself. The spraying was conducted between 9 a.m. and 1 p.m. in Eatonville and 4 a.m. and 8 a.m. in Puyallup.
Jim Marra, WSDA's managing entomologist, said workers had to wait for the caterpillars "to hatch out and be a certain size before the spray could be effective."
The area near the mall also was also sprayed last year. With Eatonville involved this year, 2012 is the first year since 2005 that the state has sprayed two sites in the same year for gypsy moths.
State entomologists knew gypsy moths were reproducing at both locations after catching some at both locations last September. Two moths were trapped in Eatonville. One was alive, which entomologists say was the latest in any given year that the state has found any living gypsy moths. Also found at the Eatonville location were two egg masses and pupal cases, additional proof of a reproducing population, WSDA officials reported.
Gypsy moths have been detected in Washington every year since 1977, but permanent populations have been prevented by the state's trapping and eradication programs, according to WSDA. Last summer, the department set more than 17,000 small cardboard traps in neighborhoods, business districts, ports and rural areas across the state in an effort to stop any infestation from spreading.
Gypsy moths, which aren't native to the U.S., arrive in the Pacific Northwest on ships from foreign ports or by hitching a ride with people traveling from other parts of the country, according to WSDA.
Nineteen states in the east and midwest are permanently infested with gypsy moth, resulting in extensive environmental and economic damage each year, officials said.
Gypsy moths are a forest pest that attack deciduous and evergreen trees, as well as urban landscapes, shrubs and other vegetation. If unchecked, the moths can destroy large forested areas - something that hasn't happened in Washington but has occurred in other states.
In its caterpillar form, the pest attacks more than 500 species of trees and plants. The caterpillar quickly strips trees and plants of leaves, destroying some and weakening others so they are susceptible to plant diseases.
Twenty-five WSDA workers are placing 18,000 brightly colored gypsy moth traps in trees and shrubs and other foliage in an attempt to detect moth populations before they can spread. The traps, which are showing up in residential neighborhoods, business districts, ports and rural areas, will be checked every two to three weeks before being taken down in October.
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