by Laura Rodley

The brown marmorated stink bug (BMSB) was highlighted by Dr. Jennifer Forman Orth of the Massachusetts Department of Agricultural Resources (MDAR) during the Invasive Insect Certification Program for Landscape, Nursery, and Urban Forest Pests provided by UMass Extension.

BMSBs were first discovered in 1998 in Allentown, PA but are believed to have been there longer, accidentally introduced from Asia. They can damage agricultural crops by feeding on plant sap.

They were first found in Massachusetts in 2007. This insect causes cat facing — round, dark brown spots — damaging apples, peaches, corn, tomatoes, and other crops and ornamentals. “If something is succulent that has sap in it, they’ll try to feed on it. It’s an issue in vineyards,” said Forman Orth, as they can emit a foul-smelling liquid scent which can get incorporated into wine. Not all stink bugs are harmful to plants.

Their scent glands are on the dorsal side of their abdomen and the underside of their thorax. Adults are 17 mm long, have light and dark bands on their antennae, alternating light and dark bands on the bottom of their abdomen and a typical stink bug shield shape, with a dark diamond shape on the bottom of their body where the wings are exposed.

They have many native look-alikes, such as the spined soldier bug, Euschistus spp., Podisus spp., Brochymena spp., and shield bugs. They are also often confused with the locally non-native western conifer seed bug.

The BMSB does not harm humans, but are bothersome due to their migration indoors in cold weather, through holes in screens, air conditioning vents, or entering barns and sheds.

With moderate to severe infestations, literally beating the plant they are on, in order to knock the bugs off, can actually be an effective measure. Bagging fruit before BMSB attacks is another option. If treating with pesticides, there are several options, including acetamiprid, a neonicotinoid. Some growers dealing with heavy BMSB infestations have had success treating the edges or first 25 percent of the crop with a pyrethroid such as bifenthrin, in order to save the rest of the crop. When using insecticides, be sure to thoroughly read and follow all label instructions. Some active ingredients, depending on the formulation or individual product, cannot be used in food crops. Look to your local Extension program for more information about safe use of insecticides. It is also possible to redirect BMSM by giving the insects something else to eat away from the crop you are trying to protect. Biocontrol is under development.

MDAR has been getting calls about BMSB for a decade. “Usually we hear from folks in the winter and fall. The majority of reports are not from growers, so we are just at the beginning levels of infestation.” Once a state starts getting multiple calls from growers, infestation levels have become a real problem. So far in Massachusetts, there has only been a single orchard on Cape Cod which has been seeing higher levels of BMSB infestation (more than 10 insects in a trap in one week).

So far in Massachusetts, BMSB is primarily just a nuisance to people. Elsewhere, people are sweeping hundreds of the bugs off their porches. There were over 20,000 in one man’s home in Virginia, mostly in his attic. “We are not there yet,” said Forman Orth.