Lowest gypsy moth count on record

Oregon enjoys lowest gypsy moth count on record
— Only one gypsy moth trapped in Oregon for 2010
By Oregon Department of Agriculture,

For now, it appears Oregon is not a top destination for gypsy moths. That is welcome news to the Oregon Department of Agriculture, which annually does battle with the destructive plant-eating insect. All 12,000 gypsy moth traps placed last spring throughout the state have been removed. Only one gypsy moth has been caught this year, the lowest count since ODA started trapping the insect in 1979. It’s also the sixth time this decade that the number of gypsy moth detections in Oregon has been in single-digits, a far cry from the mid-1980s when more than 19,000 gypsy moths were trapped in Lane County alone.

“We were hoping for zero, but catching just one is good news,” says Helmuth Rogg, supervisor of ODA’s Insect Pest Prevention and Management Program. “This means for the second year in a row, there is no planned gypsy moth eradication program in the spring. Since our program began more than 30 years ago, we’ve never gone consecutive years without a spray program for gypsy moth.”

The recent trend of gypsy moth trapping is encouraging. The number of detections dropped from 12 in 2008 to six in 2009. There was no spray program in 2002, 2006, and last year. Previously, it was all the way back in 1990 the last time ODA had not conducted a gypsy moth eradication project.

Finding gypsy moths as soon as possible and quickly eliminating breeding populations allows ODA to successfully prevent economic and environmental losses to Oregon, either through restrictive quarantines on commodities or by the loss of foliage and even trees due to expanding gypsy moth populations.

“We want to keep gypsy moth out of Oregon as long as we can, and prevention is still the best recipe for doing so,” says Rogg. “Our detection program helps keep any gypsy moth populations out there from getting big enough to cause major problems.”

ODA survey technicians began placing gypsy moth traps throughout the state in May and removed them this fall. This is the stretch of time when gypsy moths are in the adult stage. Traps lure male gypsy moths with a female sex pheromone and the attracted insects get caught by the sticky substance found inside the tent-like cardboard traps.

The lone detection this year was made in a trap located in Beaverton near Southwest 170th and Farmington Road. Normally, additional traps are placed in areas of detection to try and pinpoint any breeding gypsy moth population. This year’s detection came too late in the year for that, but a higher density of traps will be placed next spring at the Beaverton site when the 2011 detection program gets underway.

“One detection doesn’t mean too much,” says Rogg. “In many cases, we come back the next year and don’t find any more gypsy moths in that area. They just die out on their own.”

Of course, the story is different when multiple catches are reported in the same general location. That leads to a search for gypsy moth egg masses and other evidence of introduction. When all the information is collected, a decision is made whether to recommend an eradication program the next spring when the gypsy moth is in caterpillar stage. It’s another sigh of relief for ODA this fall knowing that spraying won’t be necessary next April and May.

The last eradication project took place in Eugene in 2009. Since then, no gypsy moths have been trapped in that area. With two consecutive years of no detections, the previous gypsy moth population in Eugene has been officially eradicated.

It might be tempting to think the threat of gypsy moth to Oregon has gone away. But officials are quick to warn against letting down the guard. New introductions are almost a certainty every year as people move to or visit Oregon from infested areas back east. They unwittingly bring the plant-eating insect with them on such things as outdoor household furniture or other items that may harbor gypsy moth eggs.

“Because of the economic crisis the country is facing, I expected to see less people traveling or moving to Oregon, and I hoped that would translate into few gypsy moth introductions,” says Rogg. “That probably helps explain our low number of detections. Also, the gypsy moth population back east is down a bit. But that population is cyclical. It’s going to come back in the east. We will have more people traveling or moving to Oregon again in the future. It only takes one female gypsy moth to come here and lay eggs in Oregon, to start up a new population of the insect pest.”

Oregon’s neighbor to the north wasn’t quite as lucky this year. Washington trapped 13 gypsy moths. Still, that is the lowest number in Washington since 1980.

So far, Oregon has been able to avoid the unsavory prospect of having to learn to live with the gypsy moth. That’s why the just-completed detection program will continue to be an important tool in fighting off an unwanted invader.

“The fact that we had only one detection this year shows that we have a very good program that finds gypsy moth populations while they are small and treatable,” says Rogg. “We have a good track record of eradicating small pockets of gypsy moth in Oregon as soon as we detect them. Without a good trapping program, that would not be possible.”

The Oregon Department of Agriculture’s comprehensive program of early detection and rapid response to the gypsy moth threat appears to be working well in its mission to protect the state’s natural environment and economy from the impact of an invasive species.

For more information, contact Bruce Pokarney at (503) 986-4559.

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