If you're finding an alarming number of brown, shield-shaped, foul-smelling bugs in your home, you're not alone. The latest six-legged home invader is the brown marmorated stink bug (Halyomorpha halys). "Marmorated" refers to its marble-like coloration.

Though not yet appearing by the thousands like Asian ladybird beetles in the fall and cluster flies in winter, brown stink bugs are the most recent exotic insect to invade Pennsylvania.

Native to China, Japan, Korea and Taiwan, brown stink bugs were first collected in 1998 in Allentown. Like Asian lady bird beetles, brown stink bugs invade homes in the fall in search of overwintering sites. In spring, they again become conspicuous as they search for a way back outside.

I know these stink bugs have become a serious problem because over the last several months I've gotten dozens of letters and e-mails asking how to get rid of them. Not only is it disconcerting to see so many conspicuous insects (they're about two-thirds of an inch long), but they get their name from the foul odor they emit when annoyed or handled.

The first line of defense is to seal all openings to the outside that insects can use to enter the house. This means caulking around door and window frames, utility pipes, light fixtures and baseboards. And repair or replace any damaged window and door screens.

If stink bugs are already in the house, crack windows and let the light lead them to the outside. For more immediate results, suck them up with a vacuum cleaner. This is how my wife and I control our lady bird beetles, and it's very effective.

I do not recommend using insecticides or other toxic chemicals inside the house. It just isn't worth the health risk.

John Rawlins, curator of invertebrate zoology at the Carnegie Museum of Natural History, agrees. In an e-mail he writes, "I concur with your method of control. ... I do not advocate pesticides ... just assure people that these things stink, but don't harm anybody. There's no magic cure for yet another immigrant into the northeastern U.S. from northeastern Asia."