Our Better Nature: The Scourge of Stink Bugs

Being a descendant of Irish and German immigrants, I like to give new arrivals the benefit of the doubt. But I make an exception for one group: I think six-legged migrants coming ashore in North America should be viewed as dodgy until proven otherwise.

Sure, a few insects from overseas are beneficial, but that doesn’t stop them from bugging us. Found in all fifty states, multicolored Asian lady beetles appear in droves each fall looking for rent-free winter housing. They were imported starting in 1916 to control aphids and other crop pests. While they do eat bad bugs and don’t actively cause harm, large numbers can find their way indoors and become a nuisance.

Some invasive species damage crops, hurting farmers and the economy in general. First discovered in Pennsylvania ten years ago, the spotted lanternfly has spread to 18 states. These pests feed on grapevines, killing vineyards and costing grape growers millions of dollars. It’s small consolation that lanternflies don’t invade homes.

However, one fairly recent arrival is both a nuisance and an economic threat, a foul character indeed. Native to eastern Asia, the brown marmorated stink bug or BMSB was first found here in 1998. It uses a straw-like beak to suck the life out of at least 100 different kinds of plants, especially fruits and vegetables. They bring heartbreak to gardeners and economic losses to orchardists. Not only is the BMSB hard to control with pesticides, it has no efficient predators. As a result, populations can build rapidly.

When I initially heard of the BMSB, I was confused, since I knew “marmorated” was a delicious jam made with orange peels, sugar, and usually without bugs (oh wait, that’s marmalade). Apparently, the term refers to the bands of light and dark colors around its abdomen. I assume “brown-banded bug” was too alliterative.

The shield-shaped adult BMSB is one-half to five-eighths of an inch long by roughly a half-inch wide. It is best identified by its color pattern, marbled brown on top with alternating bands of brown and tan on antennae and along the edges of their abdomens. Immature forms change color and shape as they progress through a series of life stages. Hatchlings are an eighth-inch long with an orange and black paint job, becoming black before maturing.

More prevalent in the Northeast, the mid-Atlantic, and along the west coast, the BMSB has been found in at least forty states. It causes the most harm to fruit crops like peaches, apples, berries, and cherries, as well as corn, tomatoes and other veggies, with losses in the tens of millions.

But you can’t put a price on tranquility if your house is overrun with BMSB. As cool fall weather sets in, they seek shelter, which in their native range (where predators keep their numbers down) means hiding under loose tree bark. But in new lands such as North America, Australia, and New Zealand where nothing much preys on them, populations go through the roof, and they swarm into attics and walls in such numbers that people have swept up buckets of the stinkers. And removing them is not fun. As their name suggests, they emit a pungent odor when disturbed or killed. They also leave enduring stains when crushed.

Managing BMSB is a two-part task. When they show up indoors, whole-house foggers or “bug bombs” may come to mind, but in this case they aren’t the answer. Although a lot of BMSB will die, the vast majority will be cached where aerosol pesticides can’t reach. Also, large numbers of dead stink bugs in wall cavities may lead to odor problems and attract pests such as larder beetles and carpet beetles.

Unfortunately, BMSB will keep coming out of the literal woodwork over time, so the weapon of choice is a vacuum. Be advised this might make your hoover smell for a while. A shop vac that lives in a garage or shed is ideal, but taping an old nylon to the hose end creates a mini-bag where bugs get trapped and can be tossed into soapy water where they’ll drown in minutes.

Above all else, managing BMSB in buildings means excluding them. Nothing else will control BMSB, Asian ladybeetles, boxelder bugs, and other home invaders like battening down the hatches. To that end, the U.S. Environmental Protection Agency recommends taking these steps:

• Weather-strip entry doors and install door sweeps if daylight is visible around door perimeter.
• Caulk windows inside and out.
• Rake debris and vegetation from your home’s foundation. Inspect for and seal foundation cracks.
• Secure crawlspace entries.
• When insulating exposed plumbing pipes around foundation or crawlspaces, caulk small gaps and fill larger ones with steel wool.
• If you have a fireplace, screen the top of the chimney to keep out pests.

Fortunately, samurais are on the way in the form of the samurai wasp, a tiny non-stinging wasp native to parts of Asia. They’re a kind of parasitoid, an insect that lays its eggs on the bodies or eggs of other species. Once parasitoid eggs hatch, the babies eat the host critter or egg alive, thus ruining their day.

Samurais and other biological controls are studied before release to prevent mishaps like the tragic case of the Old Lady Who Swallowed a Fly.

But in a plot twist more fitting to ninjas than samurais, before it was cleared for release, the wasp suddenly appeared in Maryland in 2014, and the following year in Washington state. Since then, many states have begun programs to rear and release samurais, but it will take time for their numbers to catch up with BMSB.