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Spread of Sweaty Sock-Scented Bugs Alarms Growers, Scientists

Vaughn Walton
Oregon State University
Invasive stink bug on an olive branch in the Willamette Valley.

A malodorous invasive bug has gone from a worry to a certifiable nuisance for some Northwest farmers and gardeners. The name of this insect is a mouthful: the brown marmorated stink bug.

Researchers say the population really seems to have taken off this year. With the approach of winter, these stink bugs are leaving the fields and may just crawl into your home.

A Little Bit Like Sweaty Socks

One of the ways scientists are following the spread of the non-native stink bug is by setting traps. There are four traps at the edge of a blueberry field at Oregon State University's North Willamette research farm.

Credit Tom Banse
The brown marmorated stink bug is 1-2 centimeters in length.

OSU entomologist Vaughn Walton is looking for a brown bug with a body in the shape of medieval shield and distinctive white stripes on its antennae. It's about the size of the fingernail on your ring finger.

It's called a stink bug for good reason.

Walton generously gives me an opportunity to smell a brown marmorated stink bug. It's a slight aroma—a little bit like sweaty socks.

"Many people say it's like a cilantro flavor," said Walton. "Some of the people in my lab used to like cilantro. Now they hate cilantro."

Commercial Crop Damage

Here's why this bug invasion raises alarms. A stink bug can transmit that flavor into berries and fruit when it feeds. It can hide in wine grape clusters and then taint the juice when the grapes are crushed. Early season attacks cause shriveling of berries and nuts. On vegetables, stink bug bites cause blemishes.

"I'd say this year it started to become way more alarming than last year because we are finding it in commercial crops," Walton said. "We didn't see them as easily in commercial crops last year. I think one of the main reasons is that this season was really perfect for them to multiply. We're looking at at least two generations this year."

Credit Tom Banse
OSU entomologist Vaughn Walton and Wilbur-Ellis agronomist Michelle Armstrong check a trap for stink bugs near Aurora, Ore.

 There are native stink bugs in the Northwest, which farmers typically don't worry about. This more voracious variety comes from East Asia. Scientists detected it for the first time in the American Northwest in Portland in 2004.

Walton says the bug has spread south to Ashland, north into Washington and east up the Columbia River Gorge through to Walla Walla.

"They are really good hitchhikers. They move on cars, on cargo, on trains and stuff like that," he said.

Washington State Department of Agriculture managing entomologist Jim Mara says he's getting reports of crop damage for the first time this year. His counterpart in Idaho reported the state's first detection of the invasive stink bug in Nampa last year.

'I Don't Have a Lot of Options'

Back in the Willamette Valley, Michelle Armstrong and her fiancé grow sweet corn and vegetables in the vicinity of Brooks.

"Hopefully we'll learn how to control this pest," said Armstrong. "We definitely see it as a major threat."

Numerous universities are looking into control measures using U.S. Department of Agriculture funding. But Armstrong says nothing has come on the market yet that specifically targets this insect.

"That's part of the worries for the growers," she said. "As a grower myself, what will I do when this pest gets in my field? I don't have a lot of options. We don't want to spray more than we have to."

Now that we've come to the end of the growing season, the invasive stink bugs are looking for comfy places to hibernate. They could crawl into your home given the opportunity.

Researchers want to hear from you if you find brown marmorated stink bugs. you can report stink bug findings by email to

Correspondent Tom Banse is an Olympia-based reporter with more than three decades of experience covering Washington and Oregon state government, public policy, business and breaking news stories. Most of his career was spent with public radio's Northwest News Network, but now in semi-retirement his work is appearing on other outlets.