The dirty dozen have become the stinking 13 with the latest invasive pest alert by USDA-APHIS and university entomologists across the U.S. for growers to be on the lookout for the brown marmorated stink bug (BMSB).

BMSB joins Asian citrus psyllid, Asian longhorned beetle, citrus greening, emerald ash borer, European grapevine moth, European gypsy moth, false codling moth, light brown apple moth, Mediterranean fruit fly, Mexican fruit fly, Oriental fruit fly, and sudden oak death and dangerous invasive pests.

BMSB has been found in 29 states. It has become established in northwest Oregon and has been found in Vancouver, Wash. One was picked up five years ago in a storage facility in Vallejo, Calif., where a family from Pennsylvania recently relocated. It was also found two years ago in air freight at a Southern California airport.

Eastern Pennsylvania is where it was first collected in the U.S. in September 1998. It was believed to have reached the U.S. on a cargo ship from Asia.

Larry Hull, a Pennsylvania State University entomologist based at the Fruit Research and Extension Center in Biglerville, Penn., said even through it has since been found in parts of New Jersey, Maryland, Virginia and West Virginia, the insect had not caused any significant damage to tree fruit crops until this past season. “Some growers in Maryland and northern Virginia had complained about damage from the insect in 2009,” Hull says. “But, 2010 was the first year when things really got out of hand.”

This past season, he notes, some Pennsylvania peach growers lost as much as 50 percent to 60 percent of their crop to the insect which feeds directly on the fruit. “All the forces (early bloom and very, dry warm weather) came together to create very high BMSB populations and caught everyone off guard,” he says.

Among other crops, it feeds on grapes, citrus, blackberry, sweet corn, field corn and soybeans.

According to entomologist Walt Bentley, University of California IPM specialist based at the UC Kearney Ag Center in Parlier, Calif., BMSB has been found in tree fruit orchards in Oregon.

Growers should take finds of unknown stinkbugs seriously and report them to county agriculture commissioners immediately.

“We missed EGVM for a few years and then it became established,” he says. Unlike EGVM, BMSB poses a bigger threat since it feeds on a host of cultivated, ornamental and wild hosts.

(BMSB) is native to China, Japan, Korea and Taiwan where it is a major economic pest, attacking a variety of high value crops.

Adult BMSB resemble other stinkbugs. They have a marbled pattern on their backs and specialized mouthparts that enable them to penetrate and feed on plant tissues. Feeding results in deformed fruit (cat‐facing), and internal brown spotting that renders the fruit unsuitable for the fresh market.

The BMSB can emit a foul odor; the presence of BMSBs in wine grape clusters at harvest and crush may contaminate the fruit and impart their foul bitter‐sweet odor to the wine.

The name “marmorated” is from the Latin word for marble, “marmor.” The back of the adult has a marble-like pattern, hence the name.

Devastating potential of BMSB

The devastating potential of this insect has triggered a flurry of research activity by state and federal agricultural researchers.

USDA-ARS researchers in West Virginia say there are two full generations of BMSB beginning with the previous year’s overwintered adults in the spring. These become active, move into orchards and start to feed and mate. Egg masses are laid with nymphs hatching soon afterwards. The nymphs feed voraciously while undergoing five nymphal stages before developing into adults, ending the first cycle of the year. By September the second generation of adults is present and may begin to leave the orchard to overwinter. Warm spring and summer conditions could permit the development of two or three generations. However, in parts of sub-tropical China, records indicate from four to possibly six generations per year.

Mass migrations of adults flood into urban areas, including homes, looking for a warm place to overwinter causing public outcry. Although harmless to people, their unpleasant odor emitted when disturbed make them equally unpopular with urbanites.

Adults are approximately 17 mm long (25 mm = 1 inch) and have shades of brown on both the upper and lower body surfaces. They are the typical “shield” shape of other stink bugs, almost as wide as they are long. To distinguish them from other stink bugs, look for lighter bands on the antennae and darker bands on the membranous, overlapping part at the rear of the front pair of wings. They have patches of coppery or bluish-metallic colored puntures (small rounded depressions) on the head and pronotum. The name “stink bug” refers to the scent glands located on the dorsal surface of the abdomen and the underside of the thorax.

The eggs are elliptical (1.6 x 1.3 mm), light yellow to yellow-red with minute spines forming fine lines. They are attached, side-by-side, to the underside of leaves in masses of 20 to 30 eggs.

There are five nymphal instars. They range in size from the first instar at 2.4 mm to the fifth instar that is 12 mm in length. The eyes are a deep red. The abdomen is a yellowish red in the first instar and progresses to off-white with reddish spots in the fifth instar. Protuberances are found before each of the abdominal scent glands on the dorsal surface. The legs, head and thorax are black. Spines are located on the femur, before each eye, and several on the lateral margins of the thorax.

According to Oregon entomologists, there are several native stinkbugs that closely resemble BMSB. Rough stink bugs, and their relatives, are often encountered. Adult rough stink bugs can be easily distinguished from adult BMSB. Rough stink bugs have distinct teeth on the edges of the thorax, or “shoulders,” just behind the head and all the antennal segments are one color. BMSB have no teeth on the edges of the thorax and the last two antennal segments have white bands.