It’s often summer pruning that turns up brown marmorated stink bug (Halomorpha halys) eggs and nymphs, but cut flowers can harbor them too.  The brown marmorated stink bug (BMSB) has piercing-sucking mouthparts with a straw-like stylet that sucks plant juices. They feed on leaves and stems but prefer reproductive structures like fruits, pods and seeds.
BSMB is also a homeowner nuisance pest because it has overwintering habits to seek shelter in residents’ homes, similar to boxelder bugs and lady beetles.

BMSB first showed up in Oregon in 2004, and feeds on more than 100 plants, particularly vegetables, pears, apples and hazelnuts, but also ornamentals. You can find more information about these pests here and report a sighting in the OSU tracker. BMSB is now present in counties throughout Oregon, but is most prevalent in the Willamette Valley, where it can be found in urban, rural, and natural areas.

Oregon has offered BMSB a comfortable environment with abundant habitat and fewer natural enemies than it has in its native range of China, Korea, and Japan. However, that may be changing as the Samurai Wasp (Trissolcus japonicus) was discovered in 2015 along the Oregon border in Vancouver, WA and in 2016 in Portland. This minute wasp (1-2 mm) is BSMBs chief natural enemy in Asia and has recently been found in Salem and Beaverton, and we expect that it will continue to spread.

Female Trissolcus wasps seek out the egg masses of BMSB, and they lay their own eggs inside. Instead of the BMSB eggs hatching with BMSB nymphs, they instead produce a new set of wasps. The wasps don’t sting people and a clear sign of their activity is BMSB egg masses that darken to a black color.

OSU scientists are tracking the Samurai Wasp and redistributing
to selected sites in Oregon.