Mike Klaus, entomologist with the Washington State Department of Agriculture.

Mike Klaus, entomologist with the Washington State Department of Agriculture.

Washington State’s Apple Maggot Working Group is recommending that part of Chelan County be quarantined for apple maggot.

Apple maggot is a pest of concern in some foreign markets, including Canada, Mexico, Chile, and Cuba, as well as in some U.S. counties.

The pest is native to the eastern United States and Canada. It was first detected in Washington in 1980 in Clark County and soon spread throughout the western part of the state. Apple maggot flies are generally found in unsprayed backyard or roadside fruit and spread very slowly, but they can be transported around the state in infested apples from backyard trees, according to Mike Klaus, entomologist with the Washington State Department of Agriculture.

Areas where the pest is established have been quarantined to prevent the movement of homegrown fruit. All of western Washington is now quarantined, as well as Spokane County in eastern Washington and parts of Kittitas and Yakima counties in central Washington. Commercial fruit shippers in quarantined areas need permits to ship outside the area. The apple maggot quarantine applies to all fresh apples, including crab apple, as well as noncommercial cherries and pears, and plums, prunes, quince, and haw fruit.

“Our goal is to keep apple maggot from getting into commercial fruit,” Klaus said during the North Central Washington Apple Day in Wenatchee in January. “We’ve been able to do that so far. But it’s a difficult insect to eradicate because there are of lot of people moving stuff around. Don’t move home-grown fruit.”


Each year, the Washington State Department of Agriculture conducts a survey of apple maggot, which helps the state develop strategies to manage the pest and prevent it from becoming established in new areas. The survey also helps determine which areas of Washington officially qualify as “pest free,” meaning that the pest is not established and efforts are being taken to prevent its establishment.

In the 2011 survey, 35 apple maggot flies were caught at 23 sites in Chelan County, which is not quarantined. Fifteen of the sites were in Leavenworth, six were along Campbell Road near the Blewett Pass Highway, and two were in Wenatchee. Pupae were reared from infested apples at two sites in Leavenworth.

The proposed quarantine area in Leavenworth would include all of the county west of approximately where Chumstick road intersects with Highway 2 and extend north to the border with Okanogan County and south to the Kittitas County border. The proposal will be submitted to the Washington State Department of Agriculture, which will hold a rulemaking hearing. Klaus said, if approved, the quarantine would likely go into effect sometime before August 1, 2012.