A. The brown marmorated stink bug (Halyomorpha halys) is a new pest in our area. It was accidentally introduced into eastern Pennsylvania in the late 1990s and has been reported in 26 of Pennsylvania's 67 counties to date, including Allegheny County. These stink bugs are native to China, Japan, Korea and Taiwan, where they are considered important agricultural pests in orchards, ornamental plant nurseries and soybean fields.

They are varying shades of brown on both sides of their bodies, with light and dark bands alternating on their antennae and dark bands along the edges of their wings at the rear of their bodies. Mature insects are just under 1 inch long and have the "shield shape" characteristic of true bugs in the order Hemiptera. Like Asian multicolored lady beetles and boxelder bugs, brown marmorated stink bugs like to hibernate in our houses for the winter. They do not eat fabric or furniture and are not known to bite people or pets. They do cause concern when large numbers of them congregate on the sunny sides of houses in the fall, looking for a way in. They repeat this behavior in reverse in the spring, congregating on interior walls, looking for a way out. They emit an unpleasant odor when crushed or disturbed (hence the name "stink bug"). Researchers believe there is one generation of bugs a year in Pennsylvania's climate.

The best way to deal with them is to keep them out of your house. Screen all openings and attic vents. Make sure your window screens do not have holes in them and that the weather-stripping on doors fits snugly. Caulk all cracks around window and door frames, openings where utility pipes and wires enter your house and any other opening to the outdoors.

You can reduce stink bug congregations outdoors with sprays of synthetic pyrethroids, including the active ingredients cyfluthrin, deltamethrin, lambda-cyhalothrin, sumithrin or tralomethrin. A licensed structural pest control operator should apply these products in the fall, just before insects begin to congregate. Since many pesticides are broken down by exposure to sunlight, the residual effect of such applications may not last more than a week.

Do not spray these products inside your home. They will not prevent insects from coming in through unsealed crevices. Even though these products may kill many insects in wall voids, their decaying bodies may attract carpet beetles that will damage wool fabrics, grain products of all kinds, pet food and many other food items. Use a vacuum to remove brown marmorated stink bugs and change the bag or empty the canister frequently.