12 Facts About the Brown Marmorated Stink Bug

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iStock.com/claudiodivizia

There are about 5000 species of stink bugs, shield-shaped insects that belong to the family Pentatomidae. One of the most notorious stink bugs is the brown marmorated stink bug (Halyomorpha halys Stål), a.k.a. BMSB, which The New Yorker called “the most destructive, the most annoying, and possibly the ugliest” of all the stink bugs, an invasive species that’s taking North America by storm … and not in a good way. Here’s what you should know.

1. IT MADE ITS WESTERN HEMISPHERE DEBUT IN PENNSYLVANIA.

A stink bug
iStock.com/sdominick

Native to East Asia, the first BMSB specimens in the U.S. were collected in Allentown, Pennsylvania in 1998, but the bugs likely arrived a few years prior to that. (They may have come to the states in a shipping container, but no one’s sure.) Since then, they’ve spread to 43 states and will probably be continent-wide soon.

“It’s an incredible hitchhiker,” Dr. Tracy Leskey, an entomologist with the Agriculture Department’s Appalachian Fruit Research Laboratory, told The New York Times of the BMSB. Less than 10 years after it was identified in the States, it was in Switzerland and other parts of Europe, too.

2. IT TOOK YEARS TO IDENTIFY IT.

A magnifying glass on a yellow background.
iStock.com/solidcolours

When the bugs were delivered to Karen Bernhard, an entomologist at Pennsylvania State University’s Extension Service, she had no idea what they were—and neither did anyone else. (Many assumed it was the native Euschistus servus.) It wasn’t until 2001, when Bernhard sent specimens to Richard Hoebeke, an entomologist specializing in invasive species who was then working at Cornell, that they were identified as brown marmorated stink bugs.

3. IT’S NOT CUTE.

Brown marmorated stink bug eggs hatching on a leaf.
iStock.com/flowerino

After they hatch, the black-and-red nymphs go through five molts, growing into mottled, dull-brown bugs—up to .66 inches long—with white banded antennae and legs, alternating dark and light bands on the abdomen, and smooth, rounded shoulders. All of these features distinguish them from lookalikes like the brown, rough, and one-spotted stink bugs. BMSBs can live for up to eight months.

4. THEIR SPRAY HAS SOMETHING IN COMMON WITH CILANTRO.

A bunch of cilantro tied together with a string
iStock.com/MmeEmil

Skunk. Old socks. Coriander. These are just some of the things the stink of the brown marmorated stink bug has been compared to. The two main chemicals responsible for the BMSB’s stinky spray are trans-2-octenal and trans-2-decenal. The latter is what gives cilantro its smell.

The chemicals in the spray might have a purpose besides scaring away predators: According to a 2016 study, they “inhibit the growth of bacteria”; the results of the study “suggest that brown marmorated stink bug aldehydes are indeed antibacterial agents and serve a multifunctional role for this insect.”

5. THEY EAT YOUR APPLES …

Brown marmorated stink bug feeding on an apple
iStock.com/saraTM

Brown marmorated stink bugs chow down on more than 100 types of crops. According to StopBMSB.org, apples, Asian pears, green beans, sweet corn, peaches, tomatoes, peppers, and Swiss chard are among the crops BMSBs pose the most risk to. Apricots, blueberries, broccoli, cauliflower, sweet potatoes, and turnips are also on the menu (though they’re less at risk).

To feed, the bugs pierce the skin of the plants with their mouthparts and drink the fluids, which in fruits like apples “results in a characteristic distortion referred to as ‘cat facing,’ that renders the fruit unmarketable as a fresh product,” according to a Penn State Extension article on the bugs. In 2010, mid-Atlantic farmers estimated that BMSBs caused $37 million in damage to apple crops alone. Some farmers of apples and other crops reported total losses that year.  

6. … AND COULD INVADE YOUR HOME BY THE THOUSANDS.

A stink bug on a model of white house
iStock.com/ibunt

Come winter, BMSBs are looking for a warm place to shack up so they can enter diapause, a hibernation-like state that lasts until spring (a.k.a. mating season). Outdoors, they’ll overwinter in dead trees—but often, they find their way into peoples' homes through open windows and doorways, in the gaps around window air conditioning units, down chimneys, and basically any crack they can find.

According to The New Yorker, “Studies have shown that, despite their relative heft, stink bugs can crawl through any crevice larger than 7 millimeters, which means that, no matter how much caulk and weather-stripping and patience you possess, it is virtually impossible to stink bug-proof a home.” But that doesn’t mean you shouldn’t try; experts recommend placing screens over windows and vents and making liberal use of caulk to patch cracks.

Once a stink bug has found a warm spot it likes, it will release an aggregation pheromone (which can linger for up to a year) that draws other BMSBs to the same area, where they’ll gather in sometimes staggering numbers: One study found more than 26,000 of them living in a Maryland home.

The good news is, beyond being a smelly nuisance, they won’t mate in your home or cause structural damage (though they might clog chimneys ... or your pipes).

7. ONCE INSIDE, THEY’RE HARD TO GET RID OF.

A stink bug on a piece of wood.
iStock.com/drnadig

Some suggested stink bug removal approaches include knocking the bugs into soapy water, placing fly traps or double-sided tape in entryways, and spraying various concoctions (like garlic water) around your house. Vacuuming them up is also an option, though as the Penn State Extension article notes, “the vacuum may acquire the smell of stink bugs for a period of time,” so it might be best to avoid that tactic if your vacuum doesn’t have a bag you can easily toss.

A study showed that traps baited with the aggregation pheromone are only effective half of the year. And though foggers will kill stink bugs around your house, “it will not prevent more of the insects from emerging shortly after the room is aerated” and therefore “is not considered a good solution to long-term management of the problem.” Even expensive professional extermination efforts can be for naught.

Research by Virginia Tech has suggested that the most effective method of removal is to line a roasting pan with foil, fill it with soapy water, and place it in a dark room with a light above it to attract the bugs. According to a press release, this method—which was tested in 16 homes over a period of two years—“eliminated 14 times more stink bugs than store-bought traps that cost up to $50.”

8. THEY’RE PRETTY GREAT FLIERS.

In the home, stink bugs are lethargic, buzzing around clumsily thanks to diapause. But in the wild, they’re good fliers: Research has shown that, in flight mill tests, the bugs can fly 1.2 miles in a 24-hour period, and in field observations, they fly in a straight line at 6.7 mph. You can see one flying in slow motion here.

9. THEY’RE GENERALLY NOT HARMFUL.

A puppy with a leash in its mouth.
iStock.com/sawiemander

BMSBs don’t sting or bite—their main defensive mechanism is their stinky spray. But some people can have allergic reactions, including rhinitis, conjunctivitis, or dermatitis, to the spray. The bugs aren’t toxic, so they won’t hurt your pets—though the chemicals in their spray might make your pets vomit or drool.

10. THEY MIGHT BE MESSING WITH YOUR RED WINE.

Pouring red wine into a glass.
iStock.com/debyaho

Not only do these pests feed on grapes, but they can end up in the mix as grapes are turned into wine, where the bugs give off stress compounds that affect the quality of the vino. Researchers at Oregon State University placed live and dead stink bugs on wine grapes and measured the stress compounds the insects released as they and the grapes were squeezed during the winemaking process. According to a press release, “They found that pressing was a key step in the release of two of the most common stress compounds—tridecane, which is odorless, and (E)-2-decenal, which produces an undesirable musty-like, coriander or cilantro aroma.” Red wine was more affected than white, maybe because the grapes are pressed at different points in the production process. The researchers found that more than three stink bugs per grape cluster resulted in contaminated wine.

11. THEY LEAVE TRACES OF THEIR PRESENCE ON PLANTS.

Brown marmorated stink bug on a plant.
iStock.com/ibunt

Scientists at Rutgers University recently discovered that they could detect the eDNA (or environmental DNA—things like skin flakes, scales, exoskeletons, or fecal matter) of brown marmorated stink bugs in the water farmers used to wash their produce before the crops go to market. They visited two farms—one in New Jersey with a known stink bug infestation and another that was just outside the bugs’ range in New Hampshire—where they both tested water and set traps for the bugs. As expected, they found stink bug DNA at the Jersey farm … and they found it at the New Hampshire farm, too. There, on the last day of testing, an immature stink bug ended up in a trap—visual confirmation of what their data was telling them. They hope that farmers can use the test to detect stink bugs before there’s a full-fledged infestation.

12. ONE OF ITS NATURAL PREDATORS IS A PARASITIC WASP THAT JUST MADE ITS WAY TO THE STATES.

A samurai wasp lays an egg in a brown marmorated stink bug egg
Oregon State University, Wikimedia Commons // CC BY-SA 2.0

In the U.S. the BMSB has few predators—so when scientists were looking for a way to combat the pests, they went to Asia. There, the stink bugs are kept in check by samurai wasps (Trissolcus japonicus), a tiny, stingerless parasite that lays its eggs in the stink bugs’ eggs, where its larvae eat the contents before emerging as wasps to continue the cycle. Sixty to 90 percent of BMSB eggs in Asia are parasitized by the wasps.

Scientists brought some of the wasps back and began testing to see if they would be a good candidate for release in the states. But before they could release any, the wasps showed up on their own, in Maryland in 2014. (Genetic testing showed that they weren’t escaped wasps that the scientists had been studying.) According to Science, “Although in laboratory tests it has parasitized some eggs laid by native species, [the wasp] has shown a strong preference for brown marmorated stink bug eggs.” Still, scientists are proceeding with caution: Though they can release the wasps in states where they’ve already been found, there are rules and regulations to follow and permissions to get before they can be released anywhere new.

The Tiger Who Came to Tea … In the Middle of Rural Yorkshire

If you lived in Holmfirth, England, in the 1940s, there's a good chance you would've found a tiger like this one wandering around town.
If you lived in Holmfirth, England, in the 1940s, there's a good chance you would've found a tiger like this one wandering around town.
photoguru81/iStock via Getty Images

According to the World Wildlife Fund, there are more tigers in captivity than there are in the wild. This is especially true in the United States, where backyard zoos and cub petting operations are successful—if controversial—businesses. Big cat ownership is more heavily regulated in the UK than it is in the U.S., but that wasn’t always the case. More than 70 years ago, there was at least one pet tiger living in England.

To the people of Britain, Holmfirth, 20 miles outside of Manchester, is probably best known as the picturesque setting of Last of the Summer Wine, the BBC show that ran for a staggering 37 years from 1973 to 2010 and is now appropriately credited as being the world’s longest running sitcom. But back in the early 1940s, the village was known locally as the home of Fenella the Holmfirth Tiger.

Fenella’s story actually begins more than 8000 miles away in South Africa, where she was adopted by a family of circus performers and acrobats from Yorkshire, the Overends, in the late 1930s. While touring South Africa with a traveling circus in 1939, the Overend family was offered two newborn circus tiger cubs to rear and eventually incorporate into their act. One of the cubs died barely a week later, but the other—given the name Fenella, or “Feney” for short—survived.

The Overends were forced to return to England after the outbreak of the Second World War. They took Fenella home with them to live (albeit after a brief stay in quarantine) in the back garden of their house in Holmfirth. Although she had a specially built hut and enclosure, the tiger eventually began spending just as much time in the family house as she did in the garden, and according to her owners, soon became extraordinarily tame.

The family would take her for walks through the village, including past the local primary school, where she became a firm favorite among the pupils. When the local council began to raise questions over just how tame Fenella really was, the sight of her walking calmly while being petted by all the schoolchildren as they returned from their lunch break was all it took to quash their worries.

Holmfirth viewed from the cemetery
Holmfirth in the 21st century, with nary a tiger in sight.

Tim Green, Flickr // CC BY 2.0

Fenella was sometimes permitted to run in the fields around the village, where she reportedly made friends with a local cart horse—which is surprising, given she was raised on a diet of horse meat and fish (fish and chips were one of her favorite treats). She apparently also had a fondness for climbing trees to take a nap, and supposedly had a habit of dropping down from the branches and, fairly understandably, surprising passersby. But soon the sight of a fully grown 9-foot Sumatran tigress casually idling her way through the village’s cobbled streets became the norm for the people of Holmfirth.

Fenella was intended to be a performing tiger. Similar to the cub petting operations that still exist in the U.S., visitors could pay sixpence to sit and pet her while the family was on tour. She was also worked into the family’s circus performances by staging a mock wrestling match with her owner. But though the Overends put the big cat to work, they considered her a beloved family pet rather than just another part of their act.

Sadly, Fenella died of a kidney infection during one of the family’s tours in 1950 when she was just over 10 years old. She was buried in the neighbor’s garden, which was said to be one of her favorite hunting grounds. Fenella is still remembered fondly in and around Holmfirth. In 2016, she was a highlight of the Holmfirth Arts Festival, which celebrated the cat’s life with an exhibition of photographs and archival footage of her and the Overend family. Exotic pets might not have remained as popular in the UK as they once were, but Fenella’s popularity at least remains intact.

Why Are Sloths So Slow?

Sloths have little problem holding still for nature photographers.
Sloths have little problem holding still for nature photographers.
Geoview/iStock via Getty Images

When it comes to physical activity, few animals have as maligned a reputation as the sloth. The six sloth species, which call Brazil and Panama home, move with no urgency, having seemingly adapted to an existence that allows for a life lived in slow motion. But what makes sloths so sedate? And what horrible, poop-related price must they pay in order to maintain life in the slow lane?

According to HowStuffWorks, the sloth’s limited movements are primarily the result of their diet. Residing mainly in the canopy vines of Central and South American forests, sloths dine out on leaves, fruits, and buds. With virtually no fat or protein, sloths conserve energy by taking a leisurely approach to life. On average, a sloth will climb or travel roughly 125 feet per day. On land, it takes them roughly one minute to move just one foot.

A sloth’s digestive system matches their locomotion. After munching leaves using their lips—they have no incisors—it can take up to a month for their meals to be fully digested. And a sloth's metabolic rate is 40 to 45 percent slower than most mammals' to help compensate for their low caloric intake. With so little fuel to burn, a sloth makes the most of it.

Deliberate movement shouldn’t be confused for weakness, however. Sloths can hang from branches for hours, showing off some impressive stamina. And because they spend most of their time high up in trees, they have no need for rapid movement to evade predators.

There is, however, one major downside to the sloth's leisurely lifestyle. Owing to their meager diet, they typically only have to poop once per week. Like going in a public bathroom, this can be a stressful event, as it means going to the ground and risking detection by predators—which puts their lives on the line. Worse, that slow bowel motility means they’re trying to push out nearly one-third of their body weight in feces at a time. It's something to consider the next time you feel envious of their chill lifestyle.

Have you got a Big Question you'd like us to answer? If so, let us know by emailing us at bigquestions@mentalfloss.com.

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