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Thursday, February 29, 2024
Feb. 29, 2024

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Are you still finding stink bugs this winter?

Insect ecologist explains why they’re in Washington


The brown marmorated stink bug is one pest that Washington residents can’t seem to shake from their homes this winter.

As of December, the pest has been detected inhabiting forests, people’s homes and devouring crops across 30 counties statewide, according to Washington State University.

Some people might be asking where stink bugs originally came from and how they managed to end up in the Evergreen State. To uncover more about the story behind stink bugs, The News Tribune spoke with insect ecologist Patrick Tobin, an associate professor at the University of Washington who studies invasive species.


It’s been over 20 years since the stink bug traveled from Asian territories and arrived in the United States near Allentown, Pa., where it was first detected in the country in 1998. Tobin and other insect researchers believe the bugs came overseas as stowaways on commodity-trading ships.

Since then, the bug caught a ride across the country and arrived in Washington in 2010. Compared to other invasive species, that is a quick travel time, Tobin said.

“We ship our commodities across the country all the time,” Tobin said. “We ship our apples everywhere … they (stink bugs) lay these really small eggs, and they may not always be picked up, and they get transported with these commodities.”

By the time the bug was detected, it had spread so fast that the USDA had difficulty implementing a plan to limit its movements, Tobin said. He added that entomologists and researchers shifted their focus to bio-control and designing pesticides to protect crops instead of trying to stop the insect from spreading.

The bug was able to establish a home for itself in the United States because the country’s climate is similar to that of in parts of Asia.

“When they make it, a lot of things lined up where they’ve been introduced at the right time,” Tobin said. “They’ve been introduced to the right climate, the food plants are available as an herbivore.”

He added that the first stink bugs in the U.S. had the genetic capacity to adapt to the nation’s climate. After that, it could begin to spread.

In homes

As it establishes itself in new territories, the stink bug might spend colder seasons inside buildings because the bug is attracted to warmth, and many crops are dormant during the winter, which reduces the bug’s capacity to feed. For that reason, stink bugs enter a phase similar to hibernation during the winter months.

Many insects spend the winter as an egg or cocoon, Tobin said, but stink bugs enter the season as adults. They feed during the spring and summer. So by the time fall and winter roll around, stink bugs looks for a place to lie low and conserve energy. Tobin added that the bug spends more energy trying to keep its body warm when it’s cold, so it looks for a place to stay warm.

If you are finding multiple stink bugs in your house, it could be because the insect releases a pheromone that attracts other stink bugs, Tobin said. When the insect finds a good spot to stay, the pheromone serves as a calling signal to other bugs.

If you see a stink bug in your home, there’s no reason to fear for your safety. The pests don’t bite and aren’t venomous, Tobin said. Residents should be able to pick them up and remove them without worry.

If you want to get rid of them for good, Tobin said, you can put them in a jar or bag and leave it in the freezer for a few days. The News Tribune has reported on other methods for catching and releasing stink bugs or creating your own traps for catching them.

Stink bug pose a larger threat to specialty-crop producers. They’re especially attracted to apples, pears, grapes, peaches, tomatoes and many ornamental crops, according to website Stop BMSB. In the United States, they pose a threat to $20 billion worth of specialty crops, according to the U.S. Department of Agriculture.

“I remember in the early days, researchers used to joke that they haven’t found anything yet it won’t eat,” Tobin said. “But I’m sure there are plants that it won’t eat, but the list is quite, quite long.”