Asian stink bugs invade Oregon

Brown marmorated stink bug
Photo of a brown marmorated stink bug from Wikimedia Commons, via The Bugwood Network at the University of Georgia.

PORTLAND, Ore. – First it was bed bugs, now another "creepy crawly" is invading Pacific Northwest homes.

The first "brown marmorated stink bug" to show up west of the Appalachian Mountains popped up in Portland's Ladds Addition neighborhood in 2004. From that single specimen six years ago, Oregon's population of these pinky-fingernail-sized bugs has grown to tens of thousands in the newest conservative estimate from the Oregon Department of Agriculture.

"One of the problems with dealing with this insect," said James LaBonte, a taxonomic entomologist with the Oregon Department of Agriculture, "is that there's no truly effective trap, nor truly effective lure."

So, without a natural predator or proven method for trapping, Oregon's population of these non-native stink bugs keeps growing. They've so far been reported from Portland west to Hillsboro, south to Tualatin, and east to Sandy and in Aurora, McMinnville and Salem.

And it gets worse.

"We've had people recently report that they are experiencing some damage in home gardens ... damage to beans, cucumbers, raspberries and several specifies of ornamental plants," LaBonte tells us. "These are the first reports of damage to those kinds of plants that we have received in Oregon."

The state of Oregon isn't alone. Before the first Portland bug was found, the species had turned up only in the East Coast states of Delaware, Maryland, New Jersey, Pennsylvania, South Carolina and West Virginia. Now Oregon is among at least 29 states where these bugs are currently nesting, swarming and damaging produce. Interestingly, Washington is not one of those states.

"From what I know [the brown marmorated stink bug] has not been recorded in the state of Washington," said Todd Murray, director of Washington State University's Skamania County Extension. "But our Department of Agriculture is out looking for them right now."

On Monday Murray sent out a "Pest Alert" on this bug to agricultural extension offices in Washington state, including the Clark County extension.
Photo of apple damage done by a brown clumsily stink bug on the East Coast
"We put a call out to our master gardeners in the area," Murray said, "so if they do see this type of bug come into our diagnostician clinics they can get it properly identified." 

What's the problem? As the "stink bug" name suggests, these bugs can stink. They have glands on their legs that give off a strong and peculiar odor, but only when when they're irritated or squashed. They fly, but only a little – mostly clumsily bumping around at distances of up to six feet.

The good news is they are docile, easy to catch and don't bite or sting. To be sure, there are around 50 varieties of stink bugs in the U.S., ranging from the beneficial rough stink bug – which feeds on fungus and garden pests – to the pesky big green stink bug, which munches on grain and other plants.

The bad news about this particular species, said LaBonte, is the trend being monitored now by the Oregon Department of Agriculture: crop damage. This comes as the stink bug populations have grown to the point on the East Coast were they're causing "extensive damage to crop lands," LaBonte says. (See more photos of crop damage provided by the Maryland Department of Agriculture in this photo gallery.)

And where they fly to is also a problem. "The adults are active now," Murray writes in his note to the agricultural extension office, "and often will aggregate on the sides of houses in preparation for wintering." And from the sides of houses to an open door, window or airway, these bugs will find their way into the relative warmth of Oregon homes. 

Where are these bugs from?
The brown marmorated stink bug hails from China, Japan, Korea and Taiwan and likely first traveled to the U.S. on cargo, according to data compiled by the ODA. The first one showed up in 2001 in the U.S.

"These things are hitchhikers, looking for sheltered spots," LaBonte said. "They will get into cars, and trucks, trains, you name it. And they will hitch rides, which may be how they got here."

However, he said "we're not sure if [Oregon's] infestation is a secondary infestation from the one in the East Coast or if ours was a second, independent introduction from Asia."

ABC Reporter Tahman Bradley reported on the East Coast invasion of these stink bugs on KATU in September (watch the video of that report). His report centered on the Northeast infestation, with the bugs popping up in vents, on walls, on windows, even in beards and omitting an odor similar to the smell of cilantro.

And where there is one bug, there soon could be a few hundred. An individual female "BMSB" – as they are being dubbed by the agriculture department – can lay about 250 eggs over her one-year lifespan. Eggs are laid in batches of 10 to 25 in the late spring and early summer. Those eggs hatch in the summer. The adolescent bugs feed on greens and other produce until the fall, when they molt and turn into adults who then overwinter and take shelter somewhere warm before emerging to feed on leafy greens in the spring, mate as many as 10 times, lay their respective batches of eggs and die. The process then starts all over again, but this time with up to 250 more bugs for every one that died.

How do I get rid of these bugs?

This week Oregon Department of Agriculture workers are setting up to 50 traps in the hopes they'll find a sure-fire way to get rid of these stinking bugs. They're using funnel traps made to trap wood-boring insects, which is where the first BMSB was found in Ladds Addition in 2004. The traps are loaded with a  pheromone known to at least attract the brown-winged green stink bug.

"The funnel traps imitate a tree trunk," LaBonte said, "and are good for insects that don't fly with great aim."

As a test the traps are being placed at several strategic sites in the Portland area where the bugs are known to be abundant, such as East Portland. They're also being placed in fruit-producing areas – such as Hood River and The Dalles – where these stink bugs have not yet been found.

The department also will test "bucket traps," a half-gallon trap the department has used for moths. Black pyramid traps are another option, known to draw in adult stink bugs but only in August. And, "next year, if funding is available, we might try some of the custom [stink bug] traps used in other areas," LaBonte said.

So what is an Oregonian to do in the meantime? Insecticidal soap is said to work on controlling these insects, though insecticides won’t deal with the offensive odor the bugs excrete when they're stressed. So the key, says an extension agent in Virginia who talked to ABC-affiliate WSET, is to go on a bug hunt. Favorite Oregon haunts for these brown marmorated bugs are the gold chain tree, Oregon ash, holly, Oregon grape, butterfly bush, catalpa and the Empress Tree.

And when you find the bugs, instead of releasing them get rid of them. Kevin Camm at the Lynchburg (Va.) extension office says this can be done with a  vacuum. It also can be done by simply whacking an infested plant with something like a stick onto a cloth or into a large bag. The bag then can be disposed of or burned. The bugs also can be flushed directly down the toilet.

Another solution could be free-range backyard chickens, known to gobble up the native stink bugs. However, these are untested in the Northwest on BMSBs and likely won't address all of the problem.

"I'm sure they'd eat BMSB as well," LaBonte said, "although probably not in sufficient numbers to put a dent in any local population." (Read more on keeping chickens in Oregon.)

- Disclosure: KATU.com Reporter Jennifer Meacham is a former news production assistant at WSET.

 

This "Pest Alert" from the Oregon Department of Agriculture shows the invasive adult "brown marmorated" bug on the left, and the native beneficial stink bug on the right. Of note is that adolescent brown marmorated bugs take on the look of the native bug until they shed their thorny-shouldered shell in the fall and emerge in their beefier smooth-shouldered adult dress:



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