Gypsy Moth Catch Rates at 20-Year High in Washington

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The Washington State Department of Agriculture has reported that it trapped 117 male gypsy moths in more than 30,000 traps this year, which represents the highest total since 1995.

The vast majority of those moths were found in Pierce County near Puyallup and Graham. Those moths were also the first actively reproducing population ever located by the WSDA. That infestation included live male and female moths and viable gypsy moth egg masses. Of the 117 gypsy moths collected this year, at least 83 are believed to have come from Pierce County. Another concentrated population was also discovered in Kitsap County.

The WSDA is currently working to complete their egg mass surveys, which are used to provide data that directs their eradication efforts. Currently, Pierce and Kitsap counties are in line for the most concentrated eradication work next year.

In 2016, more than 10,000 acres were treated for gypsy moth eradication in Washington. There were no gypsy moths caught in any of those eradication zones since that treatment. One area that saw a concerted effort was the Capitol Hill area of Seattle. That effort is considered a success by the WSDA due to the lack of gypsy moths caught in that area this year.



There was one gypsy moth caught in Thurston County, one gypsy moth caught in Clark County, and no gypsy moths caught in Lewis, Cowlitz, Wahkiakum, Pacific or Grays Harbor counties.

Gypsy moths are considered to be the most destructive invasive pest in North American forests. Last year in New England, where the different moths are permanently established, millions of acres of trees were completely defoliated and thousands of acres of trees were killed by gypsy moths.

Officials believe that the outbreak on the east coast played a role in the increase of gypsy moths found in Washington. European gypsy moths are typically transported into Washington by people moving infested areas who have egg masses on their belongings.

Additional information including a detailed map of gypsy moth catches can be found online at agr.wa.gov/gypsymoth.