The insect is the brown marmorated stink bug, Halyomorpha halys, also known as BMSB. They were first identified in Oregon during 2004 but didn’t arrive in your region until a few years ago. Their activities in Oregon so far have been mainly as a nuisance pest. BMSB remain outdoors during the growing season and seek refuge indoors during the fall and early winter. Once indoors, the good news is that BMSB don’t damage anything, they don’t bite people or pets, nor do they breed. Basically, they’re just hanging out for the winter.
It’s pretty common to find an occasional BMSB indoors but, if you have many of them, prevent more from entering your home, seal all possible entries with caulking, weather stripping, and the like. Seal the interior during fall and winter, the exterior during July or so.
Pesticides seldom work during the growing season – they may be knocked down but they commonly walk away within 2 hours – and definitely don’t work during the fall and winter. A simple and effective trap for indoor use is a shallow pan of soapy water with a desk lamp shining on it. Outdoors, you can either flick the stink bugs into soapy water or, if they are very numerous, use a wet-dry shop vac.See Pest Alert for BMSB http://www.oregon.gov/ODA/shared/Documents/Publications/IPPM/BrownMarmoratedStinkBugPestAlert.pdf