Invasive Species
Big Stink
Small six-legged Asian invaders are fouling up outdoor recreation stateside.
By Brenda Timm

Kim Phillips

Up until a few days ago, I didn’t know what a stink bug was.

I made my annual trip to southeastern Pennsylvania to watch the raptor migration at Hawk Mountain Sanctuary and to hike on the Appalachian Trail. When I drove home to Brooklyn and parked my car, stink bugs poured out from under the hood in a biblical sense. 

You may not have heard of or seen a brown marmorated stink bug (Halyomorpha halys), but Dr. George Hamilton, Professor of Entomology and Chair of the Department of Entomology at Rutgers University, says we should all brace for its arrival.
“This was an extremely bad year for stink bugs,” he says. “Normally there is only one generation of offspring. Since it’s been warmer, they have developed faster. Climate change is only going to allow populations to expand their range further north. They have already been picked up in New Hampshire.”

Originally from China, the stink bug was first discovered in the United States in Allentown, Pennsylvania in 1998 (the stink bug epicenter), and has since spread to 23 states. Maryland, Virginia, West Virginia, and southern New Jersey have been particularly hard hit with population explosions. “In West Virginia this year, they’ve seen two generations,” Hamilton told me. “That’s double the number of eggs laid.” Manhattan’s five boroughs have had stink bugs for at least a half-decade, according to Dr. Hamilton, which brought me slight relief—I thought I could have been the vector that introduced them here. 

Rutgers University

Dr. Hamilton doesn’t believe stink bugs will have the negative effect on forests like gypsy moths and Japanese beetles have had. “Their impact will be more agricultural since they feed on seed pods or any fruiting structures,” he says, adding that crops like peaches, apples, and peppers will be impacted.

The insects aren’t known to cause humans any physical harm, but if you squash them, they give off a foul smell akin to sweaty feet, bad cheese, and skunk mixed together.

“People think stink bugs are dangerous because they are loud when they fly around, but they don’t bite or sting,” says Steven Saffier, Audubon Pennsylvania's Audubon At Home Coordinator. “They are just more of a nuisance than anything.”

Jim Gaffney, owner of the Hawk Mountain Bed and Breakfast, would agree. “The heat wasn’t working in one of our rooms and I opened the plate, and there is a stink bug wedged in there blocking the connector,” he says. “And there is rarely a day where I put on a piece of clothing and don’t find a stink bug in it.”

Hawk Mountain's North Lookout

Audubon Pennsylvania

In September and October, stink bugs look for protected places to hibernate for the winter. They love rock outcroppings, like the ones at Hawk Mountain where birders sit with their binoculars counting eagles, ospreys, and hawks, but they also seek cozy human habitats. 

Because stink bugs are skilled hitchhikers, vistitors to Hawk Mountain would be wise to go through their cars, backpacks and clothing to make sure the stink bugs aren’t getting a free ride. “Now’s the time you will see them around your windows, doors, or any other entry point,” says Dr. Hamilton.

You may not even know that you have six-legged guests until around February when stink bugs try to find their way back outside to mate and lay eggs under trees, particularly ornamental ones, like the Chinese native paulownia tree (also known as the princess tree), which is their favorite according to Dr. Hamilton. “We need to rebalance the system,” he says. “It’s common when these new species are introduced that they go through what is called an ‘ecological release.’” In other words, they rapidly expand in population size after arriving, say, in a plant, leaving their natural enemy behind.

Dr. Hamilton, along with teams of scientists, the USDA, members of Congress and others are teaming up to find solutions to stave off future population growth. “We are looking at all of the options to use against it—a parasitic wasp, a fungus, traps to use outdoors and indoors, possibly in combination with traditional pesticides,” Hamilton says. “We are hoping to uncover the most effective and environmentally sound way to stop the spread.”

Will the stink bugs impact bird populations? Dr. Hamilton doesn’t think so. Can birds be a part of the solution? That might be a stretch, according to David Barber, a Hawk Mountain research biologist. “I have been here 11 years and have only seen one red-eyed vireo eating a stink bug,” he says. “Birds will not make a dent in this population.” Yet, the Hawk Mountain Facebook page reveals a number of fans who have reported seeing grackels, house finches, blackbirds, catbirds, and a red-breasted nutchatch eating stink bugs.

If you believe that you have seen a brown marmorated stink bug in your area, report the sighting to Rutgers University. To prevent stink bugs from entering your home, here are a few tips:

Back to Top