Wild Side: The BMSB

From East Asia, not with love.

A brown marmorated stink bug in my home office, as far as I know the first one ever recorded on the Vineyard. Not a welcome arrival. —Matt Pelikan

Like most naturalists, I’m a big fan of “firsts” — seeing a species for the first time, finding something never before recorded in a certain area, or observing a behavior I’ve never witnessed before. But firsts vary widely in how much they thrill me, and last Friday I scored a new low when I noticed a stocky brown bug crawling up the inside of a window in my home study in Oak Bluffs.

Perhaps three-fourths of an inch long, the critter had a distinct black-and-white pattern around the margin of its abdomen. And its lengthy antennae were banded with white. I’m not very good with true bugs in the order Hemiptera, but this one I was pretty sure I recognized: a brown marmorated stink bug, Halyomorpha halys.

Among the more loathed insect in North America, the BMSB (as it’s often abbreviated) is an exotic insect, originating in East Asia and notorious here as a domestic nuisance and an agricultural pest.

A quick check on iNaturalist, a popular “citizen science” database, showed no previous BMSB reports for the Vineyard (though, somewhat surprisingly, it does show one for Nantucket). And a quick communication with an entomologist friend who works in invasive species control confirmed that state authorities had not yet received a report of this bug from the Vineyard. So I guess I can claim the dubious honor of first documenting the presence of a noxious invasive insect on the Island.

The BMSB first turned up on this continent in Allentown, Pa., in either 1996 or 1998 (sources differ). It probably arrived in a shipment of goods from China or Japan. Within a few years, it had expanded into much of the mid-Atlantic region, earning a reputation for damaging crops, and by 2005, it had reached southern New England. A separate series of introductions around 2000 established the species on parts of the West Coast.

The first Massachusetts record apparently came in 2007, in Bridgewater, and, with its arrival on the Vineyard, the BMSB has now been found in all Massachusetts counties.

Known to feed on more than 300 species of plants, the BMSB does most of its damage by sucking juices from plant stems, leaves, and fruits with a slender proboscis. Peaches and plums appear to be most vulnerable, but many vegetables can be blemished by this insect, and in its native range, it’s viewed as a pest of soybeans.

In domestic settings, the BMSB is less damaging but still annoying. Many adult BMSBs survive the winter, and they prefer, reasonably enough, to do so in warm, sheltered settings. So they are one of a number of insects that tend to find their way into houses during the fall, sometimes in very large numbers. The bugs themselves don’t really do any harm. But if injured or just sufficiently annoyed, they produce a squirt of a foul-smelling mix of hydrocarbons from glands on their backs (hence the “stink bug” part of their name).

Oddly, different people experience the smell of these secretions in different ways: Many describe it as resembling cilantro, some find it skunklike, while others detect it as a smell like burning tires. In any case, it’s not a smell you want dominating your house. In occasional cases, the secretions can also cause mild irritation on contact with skin.

Fortunately for us, the vigor of this species seems to decline with increasing latitude, and in Massachusetts, it has not yet achieved an abundance that makes it either economically harmful or much of a nuisance. But in the Mid-Atlantic states, the bug is a serious problem, and in the context of climate change, it is likely to be a blight on the Bay State in the not so distant future.

Superficially similar to a variety of other bugs, the BMSB’s chunky shape, white-banded antennae, and marble-like (“marmorated”) markings on the abdomen edge make this bug fairly easy to ID. There are some brown native stink bugs that resemble it in shape, but are much less problematic. And a variety of so-called leaf-footed bugs, which often show the same domestic preferences for overwintering, differ in being more elongated in shape and sporting leaf-like flanges on their hind legs, which the BMSB lacks.

Given the flow of vehicles and goods between the mainland and the Vineyard, the arrival of the BMSB was inevitable, and the one I found was surely not the first to make it here. Biologists are working on various approaches to controlling this species, including possible future releases of parasitic wasps that lethally infect BMSBs.

For now, if you find one, you’re invited to do what I did with mine: Freeze it, to kill it without releasing the bug’s noxious juice, and send it off in the trash. As much as I value biodiversity, this is a piece of diversity we can do without.