Every year when the weather starts to turn chilly, we notice an uptick in the number of pests that try to come into our homes for the winter. Some of them can be a real nuisance, especially in the case of one particularly smelly uninvited guest—the brown marmorated stink bug. The main threat they pose when they do invade our space is to our sense of smell, but many people also find these insects icky to have around, especially considering they’ve been known to gather in huge groups in houses like a scene out of a horror movie. We've rounded up a few important facts to know about these creepy-crawlers, plus some helpful hints for keeping them at bay.
1. Brown Marmorated Stink Bugs are Invasive
Numerous stink bug species are native to the U.S., but brown marmorated stink bugs originated in East Asia. They made their way to the U.S. in the 1990s, and were first discovered in Allentown, Pennsylvania, in 1998. Since their arrival, they’ve spread across the country at a rapid rate, and have been spotted in nearly every state. They don’t have many natural predators in North America, so their population has exploded in the 20 plus years since they arrived.
2. They Like to Gather in Groups
Unlike native stink bugs, this species seeks out protected structures like houses and garages to spend the winter, usually by the hundreds and even thousands. So if you start out dispatching a stray stink bug here and there, you may think the problem is solved, but it's likely just beginning. Once one of these insects has found a warm, cozy, spot to wait out the winter, it can release pheromones that attract others to join it (don't worry, you won't be able to smell that). Stink bugs also enjoy close contact with one other and other objects, which is why they don’t mind piling on top of each other in a small space, and why you’ll sometimes find them in snug spots like the folds of your curtains or tucked behind a hanging photo.
3. It's Nearly Impossible to Seal Your House Against Them
Preventing your home from being invaded by brown marmorated stink bugs in the first place can be tricky. Researchers at Virginia Tech have found that these insects can stuff themselves through gaps as small as three to seven millimeters. A penny is about 1.5 millimeters thick, so stacking up two will give you an idea of what three millimeters looks like. That’s pretty tiny, so while weather-stripping your windows and doors and repairing holes in screens can seal up larger entrance points, it’s almost impossible to block every crack they could squeeze through.
4. Stink Bugs Will Eat Almost Any Plant
Bad news for your garden, but brown marmorated stink bugs—as well as other species of this insect—aren’t picky. While they love feasting on fruits and vegetables (part of the reason why they’ve been so devastating for farmers in the U.S. and other places around the world, causing millions of dollars of crop losses), they’ll also gorge themselves on ornamental plants. The young ones in particular will also feed on weeds and grasses. But luckily, their appetites are limited to plants, so they won’t cause any damage to your home like termites or carpenter ants might.
5. They Won't Lay Eggs in Your House (Thankfully)
Finally, some good news! If you spot brown marmorated stink bugs in your house during the fall and winter, you don’t have to worry about them laying eggs inside. These insects go through a process similar to hibernation during the winter called diapause, which means their metabolism slows way down when it gets cold outside. They move and fly slowly (if at all), and they don’t reproduce and lay eggs until the spring. By then they’ll be out of your house and searching for the underside of a leaf to lay their eggs.
How to Get Rid of Stink Bugs
Typically, once they’re inside, brown marmorated stink bugs will look for a tiny crevice to hunker down in, like cracks in your walls or attic, but can end up just about anywhere. However, they prefer to be higher up, so will usually congregate in upper floors of a house, rather than basements. Throughout the fall and winter, keep an eye on those areas for any stink bugs that may be trying to settle in. If you find any, you’ve got a few options for getting rid of them.
Vacuuming is a solid bet to quickly remove the insects. A small shop vac works especially well because it’ll be easier to reach any bugs hanging out near the top of the wall or the ceiling. Just make sure you empty your vacuum immediately afterwards, preferably into a bag that seals—they’ve been known to survive the trip into the vacuum and crawl back out.
A homemade stink bug trap is also an option. One popular DIY trap involves filling a small tray or pan with soapy water and placing it underneath a night light or desk lamp. The insects will be attracted to the light, then fall into the water and drown.
Finally, because they can make an unpleasant odor, we consider squishing stink bugs to be a last resort. But if you do end up smashing a few, it might keep others at bay. Researchers at Virginia Tech have observed that live stink bugs tend to avoid other freshly-squashed ones. That could be worth a little smelliness, though crushing these relatively large insects—they are about three-quarters of an inch long—is definitely not for the squeamish.
Unfortunately, most insecticides labeled for household use aren’t very effective against brown marmorated stink bugs. According to the U.S. Environmental Protection Agency, common insecticides may kill these pests in your home, but they won’t prevent more from arriving. If you have a major stink bug infestation with hundreds or even thousands descending on your home, it still could be worth contacting a pest control company to help minimize the invasion.
Stink bugs are definitely a nuisance, but with a little preparation and knowledge, you can keep them at bay during the colder months. Then you can get back to filling your home with more pleasant scents like pumpkin pie and apple cider instead.