Pikes/Pines | A Capitol Hill visitor for the vacations, the Brown Marmorated Stink Bug

(Image: Brendan McGarry)

You share your home with more than pets, partners, roommates, or family. Despite our best efforts to intentionally ignore or scare away their presence, there are many other lives in our homes. Many are arthropods that are residents, or almost so, like Giant House Spiders, and others are just part-time house guests. I’ll never forget snoozing by the fire in a fall, only to wake up to the stings of the Yellow Vests that had lodged themselves in our previously smokeless chimney.

Others are more harmless, like stink bugs, which you may have seen perching on the edges of your home this fall.

One species in particular caught my eye this year: the Brown marbled stink bugHalyomorpha halys.

Native to China, Japan and Korea, these insects were first documented in the US in Allentown, Pennsylvania in 1998 and by 2004 had spread across the country to the Pacific Northwest. I can’t remember exactly when I first noticed any of them (sometime after 2017 when they showed up in King County), but it was definitely in the fall when they had started moving indoors.

You’re probably familiar with insects from the Pentatomidae family, the shield bugs or stink bugs depending on where you’re from, of which there are nearly 5,000 described species worldwide and about 50 in Washington state. They’re pretty obvious because they’re slow moving and sometimes pretty beautiful. This family belongs to the order Hemiptera, a large, diverse group of insects such as aphids, leaf hoppers, and even bed bugs, all of which have stinging mouthparts that they use to sting and slurp. If you have a snappy entomologist friend who tells you that “not all insects are beetles, but all beetles are insects,” they are referring to this order, also called the “true beetles.” Even as someone fascinated by taxonomy, it’s hard not to roll your eyes at things like this.

Now, if you search Google for “stink bug” your first hits would probably be about pest control and invasive species, mostly because of the brown marbled stink bug. While I object to this because it means many people will immediately react with fear, paranoia, and violence when they see what they perceive to be a “stink bug,” there is good cause for concern. Brown marbled stink bugs pose a threat to agricultural and ornamental crops.

Many stink bugs are generalists and feed on plants through their straw-like mouthparts. They willingly drank up agricultural crops, not only contaminating crops and fruits but also destroying seed production. They are also extremely difficult to control with chemicals because they do not readily absorb topically applied pesticides. Unless you’re a farmer (which most people reading this probably aren’t), this could be a big problem. But I know you all eat and many of you have gardens which are also on the menu.

Part of the concern is that brown marbled stink bugs are on the rise, reaping the benefits of climate change in the perfect storm of “I told you so” we’ve been hearing from climate scientists for years.

Climate change makes us all the more vulnerable to introduced species. If you’ve been paying attention to pike/pines, the biggest concern with introduced species is that they often live outside of the control mechanisms that an ecosystem relies on. Aside from another introduced wasp, there are no other known controls other than pesticides (which are indiscriminate) that we can rely on to keep brown marbled stink bug populations at reasonable numbers.

Stink bugs in general are extremely good at sneaking into cracks and hiding, which is one of the reasons non-native bugs are so good at spreading. Our trading habits are good vectors for bugs riding on a shipping container or in a crate.

While I’ve never experienced a full-blown invasion of brown marbled stink bugs anywhere I’ve lived, I’ll assert one fact: They’re not directly harmful to humans, but rather a nuisance in our homes. We don’t currently live in a place where Brown Marmorated Stink Bugs can produce multiple generations within a year (which is their average lifespan), so they can’t flock quite as much as in other parts of their range in the US. But I can also understand why having hundreds, in some cases thousands, of them in the house is problematic. I wouldn’t be down

Her name isn’t an exaggeration either. When disturbed or even crushed, they give off a far from pleasant stench. This varies between species and even the age of the beetle. It has a musty, pungent odor that I don’t want to smell on a regular basis.

Despite my reluctance to wage war on all brown marbled stink bugs, there are real reasons to be concerned about the increasing numbers of introduced species. Personally, I’m not too concerned about soybeans (I care more about our local apples and cherries), but I do care about the health of the entire ecosystem.

The biggest concern with species expansions like this is that when they pop up, we don’t always know what will happen. And in some cases, like Chestnut Blight or Emerald Ash Borer, we lost the fight before we really knew what was happening.

As generalists, we’re more likely to have a stubborn, pesky pest in the Brown Marmorated Stink Bug than a species-destroying curse. But that doesn’t mean a generalist can’t be a vector for plant diseases that we have yet to understand. It is very likely that we will lose all of our Oregon White Ash trees over the next few decades as Emerald Ash Borers make their way west. I’m not keen to see further situations where we lose entire populations of a once common species, so I can understand why attention and attention is being given to this particular bug.

Ultimately, I want people to live lives of curiosity, excitement, and empathy for the more than human world, even in vastly changed places like The Hill. It’s sad that children grow up afraid of arthropods, not because stinging and biting arthropods don’t deserve cautious respect, but because it shows a lack of connection. Marbled brown stink bugs might not be the houseguests we want, but we might still end up with them. I think they’re pretty cool looking so if anyone sparks an interest in insects I’d be fine with a few settling in my house. But not hundreds. And certainly not thousands.

SUBSCRIBE AND STAY CHS PAYWALL FREE – $1/$5/$10
We’re excited to provide free community news about CHS to thousands of readers. What keeps the effort going are voluntary subscriptions from paying supporters. If you enjoy CHS, SUBSCRIBE HERE and help keep CHS available to all. Subscribe for $1/$5/$10 per month to help CHS deliver community news without a paywall. You can also sign up for a one-time annual payment.