As temperatures cool, stink bugs start seeking shelter

The harvest is on, and the nights are getting colder. So some Marylanders have begun to wonder when the stink bugs will show up.

The experts say it won't be long. But they disagree on whether there will be fewer of them this time around, or more.

"I personally have more than last year. Others have told me they have less," said Mike Raupp, a University of Maryland entomologist. "But at this stage of the game it's like predicting the track of a hurricane. I will have a better answer in a few weeks."

The brown marmorated stink bug is an invasive agricultural pest imported accidentally from Asia. It was first sighted in the U.S. in Allentown, Pa., in 1998, and it has spread to 33 states since. While they don't bite, carry disease or breed in the home, they are causing significant damage to fruit and vegetable crops, as well as to corn and soybeans.

Most Marylanders, however, know the stink bug as a creepy pest that descends on homes and apartments in early autumn in search of shelter from the cold, and reappears in the spring en route to the outdoors in search of a mate.

Their autumnal search for shelter in homes begins in the coming weeks, said Stanley W. Fultz, a University of Maryland Extension agent in Frederick County.

"Just this week they started moving in toward my home — not inside yet — but they are taking shelter under my grill cover and patio umbrella," he said.

Exactly how much more or less numerous they're likely to be this fall isn't clear yet. But there might be clues out on the farm.

"I saw more [stink bug] activity in corn this year," Fultz said, "and I am beginning to see the evidence of damage in soybean fields."

Farmers did more spraying for stink bugs this season after Maryland and six other states won approval from the U.S. Environmental Protection Agency in June to use dinotefuran — a common pesticide approved for use against other crop pests — on stink bugs.

"We had thousands of acres of soybeans sprayed in this area, so it will be interesting to see if the treatment has any effect of reducing the damage," Fultz said.

Gerald E. Brust, an integrated pest management vegetable specialist at the University of Maryland, doesn't think the infestation is as bad this year as last.

"There is much less damage from it on an area-wide basis," he said, although he acknowledged that north-central Maryland seems to have been hit particularly hard, especially in tree fruits and sweet corn.

"There will still be problems, with the [stink bugs] getting into people's homes as they did last year, just not on the same scale," he predicted.

Bobby Black, owner of the Catoctin Mountain Orchard north of Thurmont, said he changed to pyrethroid spray products and adjusted his timing with USDA guidance, and that's knocked his losses down from as much as 50 percent last year to just 1 percent to 2 percent this year.

"We have a great crop," he said. "We're picking apples and pears; we still have peaches. It's nothing like last year … almost a complete turnaround." He hears from other growers who have also done well, and there are reports that native predators may be developing a taste for stink bugs.

But the bugs are still around, despite all the spraying in agricultural settings.

"Personally," said Fultz, "I think it is just a little bit too early to say we are not having the same level of infestation this year. I really did not see the movement toward the buildings last year until the corn was being harvested for grain, and soybeans had dropped most of their leaves," he said. "We are still a few weeks away from that this year."

Raupp said there is plenty people can do to prepare for the home invasion, however big it proves to be. He's produced an online video describing his "exclusion and execution" methods. (

Exclusion, he said, means tightening up your home to prevent the pests from slipping indoors. Repair worn weather stripping, caulk around windows, doors and cable entries, and screen open gable vents. The work may also reduce your heating bills this winter.

Execution means collecting the stinkers that get through in jars, commercial stink bug traps or vacuums, and killing them. Don't crush them; that will teach you why they're called stink bugs. Instead, just drop them into a bucket of soapy water, or seal them in a plastic bag and deposit them in the freezer for a few days.

You won't nab them all, Raupp said, but you can deal with the survivors the same way when they re-emerge in your house next spring.

Maryland weather blog: Frank Roylance on meteorology

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