Barely two-thirds of an inch long and emitting a foul odor when squashed, the stinkbug may be off-putting to all life-forms except other stinkbugs. It has, however, proved to be not only fecund but wily, resourceful, and destructive.
In 2010, the Asian invaders were blamed for spoiling $37 million worth of apples in the Mid-Atlantic region, and assessments are under way to see what kind of damage they have caused this year. They have attacked soybeans, corn, tomatoes, raspberries, and grapes. And there are few natural predators to stop them.
U.S. crop-killer is a relatively new role for a species known formally as Halyomorpha halys and hailing from China, Japan, and Korea. Its American career started when it arrived in a packing crate in Reading in 1996, according to University of Delaware entomologist Doug Tallamy.
At first, the bugs were a nuisance confined to eastern Pennsylvania and New Jersey, said expert John Tooker of Pennsylvania State University. But their ponderous ways are deceptive. "They are strong, steady fliers," he said, and also have an uncanny ability to hitch rides in boxes and cartons.
So far, they have been found in 33 states and the District of Columbia. The first one sighted in Minnesota was discovered in a microscope packing box.
"There's a lot not known about [stinkbugs]," said Tooker, ". . . because there wasn't a lot of evidence they were doing economic damage beyond a small region of the country."
Now there is evidence aplenty. So last Monday, Sen. Bob Casey (D., Pa.) announced that the U.S. Department of Agriculture was putting up $5.7 million to create a scientific SWAT team to learn about a bug that has been keeping secrets under its protective shield.
Guiding the Brown Marmorated Stink Bug Working Group - sorry, no catchy acronym - are Tracy Leskey, a research entomologist in West Virginia, and George Hamilton, chairman of Rutgers University's department of entomology.
Leskey has more than a professional interest in the bugs. She says she has "thousands" in the attic of her Victorian home. They don't bother her, she doesn't bother them.
They can enter a house through the tiniest of cracks, and once inside like to squeeze into ultrathin spaces with as many friends as they can. They aren't looking for warmth so much as shelter, Leskey said.
Once inside, they are generally harmless, although they might snack on houseplants, Tooker said. All in all, he added, they would rather be someplace else, perhaps in a tree or cliff crevice. But as winter approaches, they choose your place because it's there. "Essentially a home is a proxy for these overwintering sites," he said.
After all, the stinkbug predates the human abode by about 37 million years.
The bugs, in fact, find household warmth disorienting, the experts say, which is why they might be seen creeping around in winter. "They get inside, and then it's unnaturally warm," Tooker said, "and they start thinking it's springtime."
That's mating season for the adults. A female can lay hundreds of eggs from May through August, and it is possible that she produces more than one generation a year, Tooker said.
The best way to stave off an incursion is to seal exterior cracks that can be used as entry points.
Experts advise against pesticides once the bugs are inside. Their carcasses can make excellent food for carpet beetles. It is best to vacuum them up, dead or alive, or flush them away.
The home invasions are likely to pick up in the next few days, according to Chad Gore, an entomologist with Ehrlich Inc., whose headquarters are in Reading - stinkbug central.
Gore said the cool nights early last week were a strong hint that winter is coming, but the bugs need a touch of warmth to get them moving into the cracks. Afternoon temperatures are due to crest near 80 the next few days.
In short, this is a species not to be underestimated, Tooker warned. Its success in the New World speaks for itself.
Stinkbugs "are pretty sharp," he said. "They're not just a bumbling mistake of evolution."
Contact staff writer Anthony R. Wood at 610-761-8423 or email@example.com.