Stink bugs invade more counties, homes in Washington

By Linda Weiford, WSU News

Stink-bug-80PULLMAN, Wash. – A recent upsurge of dirty, rotten, no-good brown marmorated stink bugs in the Pacific Northwest has researchers scrambling to keep the insect’s numbers from exploding.

Since September, the agricultural pest has turned up in significantly larger numbers in traps and inside people’s homes in Washington state. The bug has been detected in Lewis and Skagit counties, bringing the documented number of inhabited counties from 17 to 19.

“It’s obvious that the brown marmorated stink bug is building its population and expanding its range,” said Washington State University entomologist Elizabeth Beers, a member of a national scientist SWAT team that’s working to track and control it. “It’s our hope that this doesn’t mark a turning point where the insect will start causing crop damage after it emerges in spring.”

The shield-shaped bug from Asia gorges on everything from apples and lima beans to flowering dogwoods. After its discovery in Pennsylvania almost two decades ago, it has moved westward and was detected in Portland, Ore., in 2006 and in Washington several years later.

‘Quite a jump’

In recent weeks, researchers in Washington have captured hundreds of the bugs in traps, mostly in Yakima and Walla Walla. In a pheromone-baited trap placed outside a Yakima resident’s home, researchers recovered nearly 200 stink bugs during a five day period, said entomologist Michael Bush of WSU’s Yakima County Extension.

Marmorated stink bugs trapped this month in a homeowner’s backyard in Yakima, Wash. They’ve also been trapped in parks. (Photo by Michael Bush, WSU)

“That compares to the 36 we captured in the entire year of 2015 throughout all of Yakima County. We’re talking about quite a jump,” he said.

WSU extension agents and master gardeners are fielding an increase in calls from people asking about uninvited, six-legged guests found in their homes and office buildings. Escaping the chill of fall, the bugs are settling into sheltered places to spend the winter, Bush explained.

“In less than two days, I heard from 27 people. To say we’ve been swamped would be an understatement,” he said.

With a notable uptick in marmorated stink bugs in Washington, no crop damage has been reported. Why not?

“In the mid-Atlantic states, homeowners noticed the stink bug species for about a decade before we saw significant damage to crops,” said entomologist Tracy Leskey of the U.S. Department of Agriculture, director of the Stop the Brown Marmorated Stink Bug SWAT team. The insect’s populations built up until they advanced into the region’s orchards, gardens and vegetable crops, causing millions of dollars in damage, she explained from her lab in West Virginia.

“It’s a scenario none of us wants to see repeated,” she said.

Wanted, dead or alive

White bands on its antennae help distinguish the insect from native stink bugs beneficial to crops.

If you see stink bugs in your home or business, WSU researchers want to know.

“It’s crucial that we track their whereabouts,” said Bush. You can either email a photograph to or place a specimen in a pillbox in the mail and send to WSU Extension Office, 2403 S. 18th St. Suite 100, Union Gap, WA 98903.

Because stink bugs emit the smell of dirty socks when crushed, don’t send samples inside envelopes, advises Bush. Also, the easiest way to tell the brown marmorated variety from other stink bug species is by the thin white bands on its antennae, he said.


Elizabeth Beers, WSU entomologist in Wenatchee, 509-679-1010,
Michael Bush, WSU entomologist in Yakima, 509-574-1600,
Linda Weiford, WSU News, 509-335-7209,


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