Brown marmorated stink bug, Halyomorpha halys (Stal), family Pentatomidae, is an invasive pest and was first found in Massachusetts in 2007. This pest is native to Asia and was introduced into the United States through shipments of trade goods.
Brown marmorated stink bugs have a shield‐shaped body that is characteristic of all stink bugs. The adults are approximately 15 ‐ 17 mm (1/2" to 5/8") long with a mottled brownish grey color. The next to last (4th) antennal segment has a white band and several of the abdominal segments protrude from beneath the wings and are alternatively banded with black and white. The underside is white, sometimes with grey or black markings, and the legs are brown with faint white banding.
Brown marmorated stink bugs feed on wide range of plant material including ornamentals, fruits and vegetable crops. The insect produces a pungent, malodorous chemical that is readily emitted when the insect is threatened. When handling the bug, the odor is easily detected. Some Maryland fruit orchard workers have report a slight allergic reaction to the chemical released by the brown marmorated stink bug.
BMSB is currently not a problem in Massachusetts (2010) according to Massachusetts Introducted Pests Outreach Project, however to monitor activity, please report any potential BMSB findings to MDAR or UMass Extension (Robert Childs: rchilds[at]psis[dot]umass[dot]edu (rchilds[at]psis[dot]umass[dot]edu)).
Fact sheet, University of Maryland: http://www.ipmnet.umd.edu/landscape/docs/BMSB-UMD.pdf