Have you noticed masses of mottled brown insects gathering on your house in fall and spring? Or dead spots on leaves, fruits and vegetables in the garden? These are signs of brown marmorated stink bugs, introduced accidentally from Asia. First identified in Allentown, PA in 1996, their numbers have been growing quickly in the Mid-Atlantic. They are also found in several Midwestern and Western states. The name stink bug comes from scent glands that release a pungent odor when the insect is disturbed or crushed. Stink bugs only harm plants and do not bite or sting. You can learn about controlling stink bugs outdoors in this article.
Adult stink bugs have a shield-shaped body that is mostly dark brown with white or grey markings. The antenna and edges of the body feature wide stripes of brown and grey. The adults lay eggs on the undersides of leaves in spring. Young stink bugs, called nymphs, hatch out in early June. The nymphs start out red or orange then change to black before maturing into the adult coloration. There are several native species of stink bugs, and the brown marmorated stink bug may also be confused with red and black box elder bugs.
Stink bugs feed on many types of ornamental and vegetable plants. Their piercing mouthparts suck out liquids. Sunken dark green spots appear on fruits including apples, pears, peaches and cherries, which can lead to rot. You often find stink bugs on blackberries and tomatoes as well. Stink bugs also cause brown spots on leaves of bean plants, buddleia, and some shade trees. If you can reach them on your plants, you can brush them off into a can of soapy water.
Stink bugs enter buildings to seek shelter for the winter and do not harm the structure of a building or reproduce within buildings. In the winter stink bugs may appear inside a house on warm days and when they emerge finally in spring to reproduce. To keep stink bugs from getting in, seal spaces around doors and windows and place screens over vents. Many stink bugs enter through window air conditioners, so remove the air conditioners in early fall. If stink bugs appear inside, use a shop vacuum to suck them up without crushing them.
Article by Sylvan Kaufman. Dr. Kaufman is a writer of popular scientific and gardening articles. She is also an ecological consultant.