Invasive stink bug could take big bite out of Michigan crops in 2017

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A brown marmorated stink bug, an invasive species in Michigan

Katja Schulz, License under Creative Commons

A brown marmorated stink bug, an invasive species in Michigan

Southern Michigan has a problem that is causing a stink. Brown marmorated stink bugs, viewed as a pest, may become a big problem this year for Michigan’s $101.2 billion agricultural industry. This big problem might have a small solution: a wasp.

Michigan has more than 80 kinds of stink bugs. The brown marmorated stink bug has recently forced its way into the group. It’s an outlier and invasive. After arriving in Michigan six years ago, the brown marmorated stink bug has made quite a stink for Michiganders. This pest has been terrorizing people in their homes, destroying crops and any kind of plant it can get to.


The bugs aren’t threatening to humans in any way except for their pocketbooks. These critters destroy crops, making it hard for farmers.

The Life cycle of the brown marmorated stink bug, according to Life Stages

Michael Downes

The Life cycle of the brown marmorated stink bug, according to Life Stages

“They are going to cause very serious crop damage here in Michigan,” said Parsons, “In Pennsylvania and New York where (the stink bug) was kind of first established and spread from they are causing millions of dollars worth of damage.”

The stink bugs damage has already been seen in Michigan, but this could be the year where the state’s crops start to take a hit.

“It’s taken about five or six years now,” said Parsons, “to where it’s really starting to get up there in numbers. This will probably be the year where we begin to see a lot of crop damage.”

When the brown marmorated stink bug gets a hold of fruit crops like apples, it catfaces them. Have you ever gone to the store and looked through the fresh Granny Smiths and seen some with little, brown rotting rings? That’s catfacing. The bugs sit on the apples and suck the juice out of them causing them to rot. Those imperfections are enough to make farmers’ products unsellable. The crops can still be eaten, but nobody wants to buy apples, or anything, with brown, rotten spots all over them.

Apples aren’t the only fruit being targeted The bugs also gnaw on field crops, berries, smaller fruits, orchards, grapes and vegetables. With large numbers of bugs, harvesting can even become a problem.

“When you are harvesting, even by machine,” said Parsons, “they can come through the machine and get all packaged up and now you have a stink bug in there.”

Stink bugs aren’t just economic hindrances. They are also inconvenient. They have their name for a reason, they have glands that spew out a foul-smelling fluid or puff of gas that has been described as “distasteful”. That’s not something that is unique for just the brown marmorated stink bug, but stink bugs in general, it’s their defense mechanism. Nobody wants stink bugs smelling up their homes, it’s unsettling. On top of that, a majority of people flat out don’t want bugs in their houses.


Scientists, entomologists and researchers at Penn State, Rutgers and Michigan State, just to name a few, have started to find ways to slow down the reproduction of brown marmorated stink bugs. One Michigan State researcher, Ernest Delfosse is studying a parasitic wasp that is from China.

“We are studying it,” said Parsons, “It attacks the stink bug eggs. It’s a little tiny wasp. It lays its eggs in a stink bug egg. Its larva eats up the stink bug egg and out emerges another wasp.”

Here’s the breakdown: The wasp eggs are laid in the host, in this case the stink bug eggs. The wasp larva hatch inside of the egg, eat the stink bug larva, and then eat their way out of the stink bug egg. The lavrae then enter their cocoons and eventually emerge as wasps. Those wasps then lay eggs, and, well, you get the point. It’s a vicious cycle, but may be effective enough to terminate the invasive bug.

Early experiments show that this could be effective in slowing the population. However, Parsons and his colleagues are worried that the wasp may threaten native stink bugs. To give you a visual of how these larva work, here’s a video of them emerging from a caterpillar (Warning: it’s haunting)


Now that we know how to potentially wipe them completely from the United States, let’s focus on something much more important, keeping them out houses, specifically yours.

“It’s difficult to keep them out,” said Mark Edinger owner of Assassin Pest Control. “It’s harder to find their entry. It’s damn near impossible, unless there is an obvious entry point. It’s usually a construction issue.”

Stink bugs can get into your homes in an infinite amount of ways. It could be something obvious, open windows or doors, but it could be something more elaborate like a chimney or cracks in the bricks mortar. Basically, if stink bugs are in your area they will try and find a way into your home, especially once it starts getting cold.

The best place to start is by trying to seal every hole possible. Check for gaps around sliding doors and screens, the bugs are attracted to light and will attempt to come in through those at night. Make sure your seals around everything are good. If not, invest in some caulk, that might be the difference maker. If everything is in good condition there might be a bigger problem. Problems or holes in your foundation, way in through siding on the house, something more expensive.

When spring comes around the bugs are at their worst. It’s warm. It’s mating season. It’s the best time of their lives. They want out as much as people want them out.

Exterminators, keep it basic.

“General crack and crevice treatment,” explained Edinger, “We use insecticides, nothing specific, there are plenty of them to choose from.”

Parsons said, “If they are inside your house you can catch them in a jar and let them loose outside, but the easiest thing to do is just vacuum them up.”

The vacuum will also suck up and contain the smell that is spewed out by the bugs. Another strategy is soapy water. Place a cup of soapy water underneath a light source over night. The bugs will be attracted to the light and more than likely fall into the soap, which will kill them.

Lets get sciency and get some information on where these bugs came from and how they operate.e


All states that have had brown marmorated stink bug sightings, according to Penn State Entomology Department

Michael Downes

All states that have had brown marmorated stink bug sightings, according to Penn State Entomology Department

Countries including China and the Koreas are known for exporting plenty of items, such as cars and electronics, to the United States. One import the U.S. didn’t count on bringing in was the brown marmorated stink bug. Viewed as a pest in those countries, according to, the stink bug chowed down on an assortment of fruits, but was mainly eating eucommia, a plant used in Chinese medicine.

This kind of stink bug hitched a ride to Allentown, Pennsylvania, in the late 1990s. The bug has now been seen in 39 states. The bug flies. It has been able to spread so fast just because of its curiosity.. However, the journey to Michigan is a unique one.

All of the counties in Michigan that have had brown marmorated stink bug sightings according to Julianna Wilson, Michigan State University Department of Entomology

Michael Downes

All of the counties in Michigan that have had brown marmorated stink bug sightings according to Julianna Wilson, Michigan State University Department of Entomology

“It was traced to a spot in Southwest Michigan,” said Gary Parsons, collection manager for Michigan State’s entomology department, “Somebody had moved from Pennsylvania or New York and brought a little metal backyard shed with them. When they got here and opened up the shed it was full of stink bugs and they went everywhere.”

From there the bug spread throughout Michigan. The “Yoopers” in the Upper Peninsula are safe from the bugs, for now. The Stink bug hasn’t been seen there yet, but is expected to make the trip over the Mackinac Bridge eventually. South of the bridge is a different story. Brown marmorated stink bugs have been spotted in every county in southern Michigan. This has a lot to do with the bug’s reproduction cycle.


The brown marmorated stink bug reproduces quickly. Once the bugs arise from their hibernating-type cycle that usually takes place inside homes/buildings called overwinters, they get to reproducing in two weeks. Since females can lay eggs more than once a summer the bugs mate several times. Females lay around 28 eggs at a time and have been known to lay nearly 600 eggs in a lifetime, which lasts six to eight months.

“Like most invasive insects,” said Parsons, “it doesn’t have natural enemies here, so it multiplies very rapidly without much to control it.”

The reproduction rates weren’t a problem in their homelands because stink bugs had predators. Without a natural predator, the brown marmorated stink bug is reproducing at a rate that is dangerous to the ecosystem and to farmers.

There is no upside to these pests, they aren’t helping in any way. For the sake of Michigan’s farmers and their crops it’s a good thing that there are people like Gary Parsons and Mark Edinger on the planet who are looking to eradicate them. They aren’t the only ones that can help out, you can too. If you happen to have them in your home or have seen them anywhere, report it.

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