Southern Oregon University senior Shannon Davis looks into a plastic box of stink bugs she captured from trees around Water Street in Ashland. A widespread infestation could bring harm to local orchards and vineyards, insect researchers warn. - Mail Tribune / Bob Pennell

Non-native stink bugs could hurt agriculture

Insect researchers are finding alarmingly high numbers of non-native stink bugs in Ashland and elsewhere in the Bear Creek Valley, and warn of a potential infestation that could foul homes and damage orchards and vineyards.

After a handful of brown marmorated stink bugs surfaced last year, they're popping up regularly this summer in Phoenix, Talent and Ashland. In Medford, the first of these bugs, commonly called Asian stink bugs, was discovered last week under a tree along East Jackson Street.

Research crews walking the streets of downtown Ashland on Thursday shook stink bug after stink bug from maple and catalpa trees, where they found freshly laid eggs, and juvenile and adult bugs.

"I was blown away by this," said Nik Wiman, an Oregon State University researcher working on stink bugs to find a way to control them. "I walked all of these neighborhoods and didn't find anything last year. Then all of a sudden this year, they're everywhere. It's pretty impressive.

"The population is increasing fast," he said. "I'd say we're at the early states (of infestation), but it's certainly coming."

Unlike native stink bugs, these insects can be considered household pests because they winter over in dwellings and release pungent odors that earn them their names.

But olfactory offenses aside, they are voracious fruit eaters and they can cling to grapes at harvest time, with their odors altering wines if crushed along with grapes.

"Oh my goodness, another pest we'll have to deal with," said Ron Meyer of Meyer Orchards near Talent.

Meyer said there are herbicides available to commercial growers to deal with these non-native bugs, but the insects also will cause problems for gardeners and organic farmers.

"We'll control them," Meyer said. "We'll do what it takes to protect our crops, but it means it will probably be more expensive."

Some Willamette Valley vineyards already have been battling these stink bugs by employing machines that shake them off the vines before the grapes are processed, Wiman said.

Pesticides also can help. Or crop owners can hope that wasps lay their eggs inside the non-native sting bugs' eggs like they do Oregon stink-bug eggs, Wiman said.

"It's just a matter of them switching over," Wiman said. "They have to adapt over time."

Wiman and his assistant, Shannon Davis, set up traps in Ashland as the team continues to work on improving trap baits to give orchardists and vintners tools to combat the bugs.

The first of these bugs in Oregon was discovered in Portland in 2004, said Rick Hilton, an OSU Research and Extension Service biologist who joined Wiman on Thursday's collections.

The stink bugs spread around the Willamette Valley, first invading homes, then backyard gardens. Last year, they began cropping up in farms, Wiman said.

Earlier infestations in Eastern states such as Pennsylvania have caused millions of dollars in agricultural damage there.

That has state agriculturists worried, particularly after Thursday's discovery.

"If it follows the pattern from back East, it's very much a matter of when, not if, it gets into agriculture," Oregon Department of Agriculture spokesman Bruce Pokarney said Thursday.

The roundish bugs are similar to the native stink bugs, which don't winter in houses and their numbers are kept in check by predators such as wasps.

The easiest way to tell the difference between the native and non-native species is that the non-native stink bugs have distinctly coal-colored antennas with a white band on them. Natives have more brownish antennae and any bands look more yellowish.

Anyone who believes they have found a brown marmorated stink bug should compare it to photographs on OSU researchers' website by visiting If they match, Wiman wants the findings reported to him at

"We want to hear from people in Southern Oregon," Wiman said. "They're definitely established and there's no reason to believe they're not going to increase."

Reach reporter Mark Freeman at 541-776-4470, or email at

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