A recent upsurge of 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 (WSU) 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, OR, 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.
“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 brown 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 USDA entomologist Tracy Leskey, 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.