Stink bugs invading the US and Southern California

The Brown Marmorated Stink Bug name comes from the bug’s brown, marbled color; also called the yellow-brown or East Asian stink bug. This pest is a recent introduction from eastern Asia. It was first collected in the United States in Allentown, PA in the fall of 1996, but apparently not recognized or identified until September 2001. They have no been identified as far as Los Angeles, CA. Its native range consists of China, Japan, Korea, and Taiwan, where it is an agriculture pest on tree fruits and soybeans. Populations of these bugs can grow rapidly so damage to crops and gardens can be severe.


Adults about 1/2-5/8" (12-17 mm) in length. Color mottled or marbled brown, with broad whitish bands on outer 2 antennal segments, wings do not completely cover abdominal margins, leaving alternating dark and pale bands of abdomen visible, and a darker area where wings overlap towards rear. Shape distinctive, shield- shaped with scutellum large and triangular but not reaching tip of abdomen. Antenna 5-segmented. Pronotum with lateral (side) margins smooth. Tibia with weak or no spines. Scent glands located on top surface of abdomen and 2 on underside of thorax that produce a pungent odor.


In the United States, adults overwinter and become active early to mid-April. They mate and lay clusters of 20-30 eggs on the underside of leaves from May through August. The eggs hatch in about 4-5 days after being deposited and the nymphs go through 5 instars. In Pennsylvania, 5th instar nymphs and teneral adults are common on foliage in August. As in most of Asia, there is probably only one generation per year.


In the United States it has been observed feeding on many different ornamental plants and trees including crab apple, American holly, Norway maple, pyracantha, and butterfly bush. It has also been observed feeding on raspberries, Asian pears, peaches, asparagus, and string beans. In general, adults feed on fruits and nymphs feed on leaves, stems, and fruit.


Before the stink bugs enter, practice exclusion. Since these stink bugs are attracted to lights, change exterior lighting to less-attractive yellow bulbs or sodium vapor. The application of a repellent pyrethroid insecticide may help for those structures whose exterior is difficult or impossible to seal.

After the stink bugs have entered the structure, it’s best to isolate the affected room or rooms by sealing the bugs out. Such rooms are usually located on the warm side of the structure. Typical entry points include around door and window frames, electrical outlets, light switches, ceiling fans, skylights, and ceiling light fixtures.

If bugs come into a room, it is not advisable to remove them with a vacuum. The problem is that after a few travel down the vacuum hose, their smell can be quite noticeable and the hose will probably have to be replaced. Instead, hire a licensed pest control company to treat the and then sweep the bugs up with a broom and dustpan a couple of hours later.