Stink Bugs

There are several varieties of stink bugs, but the brown marmorated stink bug is increasingly becoming a problem in the late summer and fall seasons. It is native to China, Taiwan, Japan and Korea, and was introduced into the Allentown, PA area of the United States in the late 1990’s, probably as a stowaway in cargo containers. Since then, it has been spreading through Pennsylvania and into surrounding states.

Adult brown marmorated stink bugs are shaped like a shield, about 0.5 – 0.75 inches long. They are a dark mottled brown color, with an alternating pattern of light and dark bands around the edge of their abdomen. They have scent glands on their body, which they often use to release their scent when they are disturbed. The scent is also released when they are crushed.

Stink bugs don’t harm people or homes, but they do have piercing mouth parts which they use to suck juices out of fruits and vegetables. The bugs typically don’t consume large portions of the fruit and vegetables. However, their feeding activity results in noticeable scarring and increased rotting, which makes the fruits and vegetables unpleasant to eat, and often not saleable.

In portions of its native areas, the stink bugs produce 4-6 generations per year, and are a significant agricultural pest. In the more temperate Pennsylvania climate, it is believed that they typically produce one or two generations per summer. Because of their somewhat limited growth season in this area, the stink bugs have been more of a nuisance rather than significant agricultural pest. However, early warm springs and hot summers, such as we are experiencing in 2010, could allow for more generations to be born, and contribute to an increasing stink bug population and problem.

Life Cycle

As the weather warms in mid- to late spring, the adult stink bugs emerge from their winter shelters. They mate from June through August, with the female laying 20-30 light green eggs in clusters on the undersides of leaves. Each generation develops through five immature (nymph) growth stages before starting to emerge in their adult stage in mid-summer. The adult is the only stage that has wings and can fly.

First Nymph Stage Adult Stage

In late summer and fall, the adults start moving to sheltered areas to overwinter, such as houses and other buildings. They enter through any opening they can find, such as cracks around windows and doors, and holes in screens and windows. They commonly winter inside the walls, but some will also migrate into the living areas of the homes. They do not reproduce in the home or buildings.

The best way to deal with the stink bugs is to prevent them from entering buildings. Seal any entry points prior to late summer, by caulking cracks around windows and doors, repairing screens, and installing weather-stripping as needed.