The adult brown stink bug is about 12 to 17 mm long. Like other stink bugs, its body is nearly as wide as it is long. The adult is mottled brown in color. There are lighter bands on the antennae and dark bands on the front wings.
The immature bug, called a nymph, is yellow and red with red eyes. As it grows, the yellow lightens to off-white.
Like many of the other stink bugs, the brown marmorated is a pest of fruits and vegetables. It has been found feeding on apples, peaches, blackberries, tomatoes, corn, soybeans, lima beans and green peppers.
Like other stink bugs, this pest pierces the skin of the fruit in order to feed. After feeding, the insect leaves. As the fruit continues to grow, it often develops a scar that resembles the face of a cat.
Besides being an agricultural pest, the brown marmorated stink bug is often a pest in homes. In late summer, the adult bugs gather on homes. The bugs are seeking sheltered places to spend the winter.
The bugs move inside the home through cracks and other openings. They spend the winter hiding inside the walls or in the attic or crawl space. When spring comes, the stink bugs become active. As they begin to move around, some of them emerge into the living space.
Inside the home, the bugs often gather on walls and windows seeking a way out. Homeowners are usually upset to find these bugs inside the home. Their size and unpleasant odor make them very unwelcome.
Females typically lay 20 to 30 eggs which she secures on the underside of the host plant in the summer. Eggs hatch four to five days later and the nymphs will begin to feed. They undergo a series of molts until they become adults by fall.