In recent years gardeners in the Mid-Atlantic States began witnessing a growing number of a new type of stinkbug invading homes and gardens. Sometimes called the yellow-brown or East Asian stinkbug, (Halyomorpha halys), these insects can damage fruits like apples, grapes, and peaches. They can also work their way indoors in fall while looking for shelter.
These garden pests are not harmful inside of buildings, but they can be annoying and hard to get rid of. Brown marmorated stink bugs are a little less than a half inch long and speckled with dark brown. Parts of this insect have patterns of dark and light bands and they have a shield shaped upper body. They are called stinkbugs because they give off an unpleasant odor when bothered or smashed. The nymphs (youngsters) are yellow with black and red speckles.
Stinkbug Habits
The brown marmorated stink bug is a relatively new problem in North America, and was first noted on the east coast in the late 1990s. It is native to Korea, Japan, Taiwan and China and may have come over as unwanted passengers in imported cargo. In the fall it can be attracted to warm, sunny building walls as it seeks a suitable place to overwinter. They are also seen on some sunny days in winter as well. Stinkbugs typically come out for the season in the spring and only reproduce in host trees or shrubs during the summer months. They will not breed inside of a home.
How Stinkbugs Affect the Garden
Stink bugs prefer to live in many different kinds of trees commonly found on the east coast. They leave evidence in the form of small spots of damage on fruit and leaves. Stinkbugs typically attack apples, figs, peaches, grapes and mulberries by sucking the sugar and water from the fruit. The bugs also feed from the stems of non-fruiting plants like lilacs. The problem is not so bad if the stinkbugs feed on non-fruiting plants, but when they attack fruit it can be destroyed. On fruits such as apples and peaches it leaves marks that kill developing cells in the fruit. These marks evolve into scars and indentations called “catfacing”, which resembles a feline countenance. (Commercial growers can’t sell catfaced because it is marred.)
Other plants like roses, butterfly bushes and honeysuckle are vulnerable to stinkbugs because they can feed on the flowers and stems. Stinkbugs also lay their eggs on the underside of leaves. To control stinkbugs in a small garden, physically pick them off of plants and destroy them. Bug trapping cards with a sticky surface also work well.
Controlling Stinkbugs in the Home
In the fall stinkbugs are a problem indoors as they can find many ways into a house to seek shelter. The best way to keep stinkbugs out of a home is to make sure they have no entry in the first place. Seal up cracks in windows and doors with caulk. Replace screens if they have holes. A mesh covering over the chimney can keep stinkbugs from coming down it. Window air conditioners often provide a point of entry so remove it as soon as the weather cools down.
Stinkbugs can be removed from the home by vacuuming with a shop-vac, but if there are too many of them their distinctive smell can be quite strong as they are sucked into the machine. Most resources recommend a professional spraying if your house is invaded by the brown marmorated stinkbug. A professional can do it but if that is not affordable the Rutgers New Jersey Agricultural Experiment Station recommends some insecticides If organic methods are preferred, some report success with a solution of fifty percent dish washing liquid mixed with fifty percent water. Others report that stinkbugs are repelled by things the bugs themselves find unpleasant to smell. Tree tea oil (mixed with water) or camphor rubbed around doors and windows is said to help. If stinkbugs collect on the sides of the house, try power washing them off daily.
For more information, see the web site Cold Climate Gardening, which has an excellent photo and diagram for identifying brown marmorated stink bugs.
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