Invasion of the Stink Bugs

Cover photo: An adult brown marmorated stink bug, the kind residents are seeing a lot of in south KC. 

As if the coronavirus isn’t enough, now there are stink bugs

By Jill Draper 

Well, this stinks. The Midwest is facing a population surge of stink bugs, those mottled brown, shield-shaped insects you may have seen crawling around your home or workplace in the last few weeks as they wake up from their winter’s sleep and search for a way outside. Although they won’t bite you or eat the food in your pantry, they do cause major damage to crops and orchards. And while the bug is considered more of a nuisance here than a serious agricultural pest, that may be changing.

“It’s established throughout Missouri and it’s building,” says Kevin Rice, state extension specialist and entomology professor at the University of Missouri-Columbia. “Most of the farmers are aware of this and that it’s coming.”

The stink bug was first documented in Pennsylvania 24 years ago. It probably hitched a ride on a shipping pallet from its native territory in China, Korea or Japan. Its natural enemy is the Asian samurai wasp, which kills 90% of its eggs. 

U.S. scientists have spent years looking at the pros and cons of importing this wasp as a biological control agent. The good news (maybe) is that while they were looking, the wasp also hitchhiked here, showing up in 2014 and spreading on its own. Hopefully, it will stick to a diet of stink bug eggs. The bad news is the situation will take time to balance out.

“It’s going to get a whole lot worse before it gets better,” Rice says.

There are thousands of stink bug species in the world, including some native to America, but the pests showing up inside homes and offices are the brown marmorated kind, dime-sized with a distinctive white band on their antennas. 

Most of them hibernate beneath tree bark and wake up during the last half of May to feed, mate and lay eggs on the underside of leaves. The tiniest young bugs look like little ticks, says Rice, who names their favorite foods as fruits, vegetables, field crops and ornamental plants. “That’s just about everything, right?” 

They especially love tomatoes, which they stab with a piercing mouth part to suck the juices while simultaneously releasing an enzyme that leaves a hard white or yellow patch, depending on the ripeness of the fruit.

The adult stink bugs seek warmth when temperatures drop in the fall, entering houses and commercial buildings through the smallest crevices. You’ll seldom find them in the basement—they prefer high spots like attics or second floors. Once inside, they settle into a state of suspended development called diapause.

According to Rice, the stink bugs waking up now are mistakenly thinking it’s summer. “They’re making bad choices,” he says.

He’s part of a large working group of 50 scientists throughout the nation who are doing research on ways to monitor and trap the bugs. One method uses pheromones and other chemicals to attract the insects, while others are experimenting with netting and various landscape factors such as tree diversity.

“There’s tons of research being funded on this,” Rice says, noting that in 2011 the stink bug caused $37 million in damages to apple growers in the Mid-Atlantic states. In the Midwest they’re particularly harmful for corn and soybeans.

Crop farmers have had some success with spraying a pyrethroid-based insecticide around the edges of fields where bugs congregate, but pesticides safe for indoor use are not very effective. Some homeowners have tried wiping window frames with heavily scented dryer sheets or duct-taping the cracks, but the bugs also slip in through chimneys, around utility pipes and through vents in air-conditioners.

Others use a Shop-Vac to suck up the bugs, but doing so demonstrates how they got their name. When squashed or frightened, stink bugs produce a putrid odor. “They taste pretty bad, too,” says Rice, who once found a bug in his water bottle.

He says the best way to deal with stink bugs that have entered a building is to trap them with a large container (a turkey roasting pan is suggested) filled with soapy water and placed under a desk lamp to attract them.

We’ll be seeing more and more of the stink bug here, Rice says, but its enemy, the samurai wasp, is now in 15 states and still traveling. Whether it takes a train, a plane or has to walk just the same, let’s hope it’s going to Kansas City.