Shaped like shields and armed with an odor, dime-size brown bugs are crawling into area homes over windowsills, through door crevices and between attic vents in such numbers that homeowners talk about drowning them in jars of soapy water, suffocating them in plastic bags or even burning them with propane torches. In the process, some people are unwittingly creating another problem: When squashed or irritated, the bugs release the distinctive smell of sweaty feet.

Get used to it, experts say: The invasion is only going to get worse.

"This is the vanguard," said Mike Raupp, a University of Maryland entomologist and extension specialist. "I think this is going to be biblical this year," he said wryly. "You're going to hear a collective wail in the Washington area, up through Frederick and Alleghany counties, like you've never heard before. The [bug] populations are just through the ceiling."

The change in season, as days shorten and nighttime temperatures start to dip, is nature's call to the brown marmorated stink bug -- pest extraordinaire -- to leave its summer gorging grounds and seek refuge inside. What's happening now is a massive population shift from orchards, cornfields and gardens, to suburban homes, office buildings, hotels -- the urban U.S. equivalents of rocky outcroppings in the stink bug's native Asia.

Stink bugs are harmless to people and their possessions. They don't bite. They don't sting. They're not known to transmit disease. But their population has grown so tremendously that they are not only causing vexation to homeowners, but also for the first time, wreaking damage to fruit and vegetable crops, from peaches and apples to soybeans and corn and even ornamental shrubs and trees.

There is no easy way to kill lots of bugs at once. They have no natural predators in the United States; existing pesticides don't work effectively. They travel easily -- hitching rides on the backs of buses, in packing materials, on cement blocks -- and adapt to winter in homes. As a result, they have flourished, spreading to 29 states since they arrived in Allentown, Pa., in 2001, likely stowaways in a shipping container from Asia. They are native to Japan, Korea and China, where they are known as "stinky big sisters."

And now they are causing a stink in the mid-Atlantic region.

Experts say homeowners should prevent the pests from coming indoors by sealing cracks with caulk and using weather stripping around doors and windows. If the bugs do get inside, residents canvacuum them up, remove the bag and put it in the garbage. The danger, though, is that squashed stink bugs can smell up the vacuum cleaner. Experts warn against using pesticides not intended for residential applications because that can cause illness and make homes unsafe -- and might not solve the problem.

In Loudoun County, longtime Middleburg resident Margo Tate uses the squish-and-toss method. Or rather, her husband does. "I'm looking out my window here and I bet I have 30 of 'em on the screen," she said. "I have to keep all the windows and doors closed. My husband smushes them and throws them in the trash. They're a mess. They smell when you squish them."

Lori Rice, 48, who runs an organic farm in Middleton in Frederick County, has had to deal with them indoors and out. She traps indoor bugs in pint jars she dubs "death jars." She puts an inch or two of soapy water in the jar and slips it under the bug so it falls in. The soap, she said, dissolves the exoskeleton. Twice a day, she flushes them down the toilet. Her biggest indignity to date: being startled awake as a stink bug was trying to crawl into her ear.

On Rice's farm, Asian pears, raspberries and tomatoes have all suffered. "If all our vegetables hadn't already withered by the heat and drought this year, the bugs would likely have broken our hearts there as well," she wrote in an e-mail. And because she has an organic farm, she does not use spray pesticides, experimenting with spraying soapy water. It works on newly hatched bugs, but adults require a stronger concentration, she is discovering.

For people, stink bugs are nowhere near the menace of bedbugs, which feed on human blood and whose alarming resurgence prompted the U.S. Centers for Disease Control and Prevention to issue an unusual statement last month about their public health impact.