The Washington Post

Invasion of stink bugs: Entomologist Michael Raupp explains

Sep 28, 2010

There's been a massive population shift of stink bugs from orchards, cornfields and gardens to suburban homes, office buildings and hotels. And experts say the invasion might only get worse. So how do we get rid of this smelly pest?

Invasion of stink bugs has homeowners, farmers seeking relief

Stink bugs do's and don'ts

University of Maryland entomologist Michael Raupp takes your questions about where stink bugs come from, why they're invading now, and how to get them out of your life.

They're everywhere! Not even the cats want to get near them, and they are usually master insect killers. What is the best way to kill them without them stinking up the place? We've been using a portable vacuum.

Ultimately, you will prevent these from becoming a nuisance in your household much the same way you prevent invasions by camel crickets or multicolored Asian lady beetles. Actions good for energy conservations will aid in your battle against the bug. Eliminate points of entry around your foundation, windows, facer boards, attic vents, and eves by screening, caulking, and repair. If the little devils are already in your home, sweep or vacuum them, and send them to the great beyond in an environmentally appropriate way.I remove the appliance from the end of my vacuum and sick them up. Some folks have purchased shop vacs for the dedicated purpose of removing these stinkers. Be sure to dispose of the vacuum bags after use because they will really get stinky. Good luck!


I remember stinkbugs around here when I was growing up in the 1960s. The current "invasion" is a new species, but what are the differences? And the predators of the domestic species won't go after the new ones? Why?

These stinkers are pretty much fresh off the boat from Asia. Unfortunately, they left their natural enemies behind. Most of the predators and parasites in the US seem unable to keep up with their ability to increase although I have seen preying mantids, assassin bugs, and spiders murdering them. The USDA is currently searching for biological control agents that can help in the battle. We will keep working and also keep our finger crossed.

We were wondering if bug zappers would be effective considering the bugs' attaction to light. This would be an insectide-free way of possibly reducing the population outside. Inside, we've put permethrin-based insecticide inside a bowl-shaped hanging light. The creatures are attracted to the light, then die upon landing on the insecticide. When the bowl gets disgusting, I dump them in a trash can.

Pretty cool approach. Scientists are experimenting with light for trapping as well and this seems to be a promising avenue. When you use insecticides especially in a somewhat experimental way, be sure to read the label and follow all precautions to protect yourself and your family.

What is the best DIY way to eliminate them - once they have invaded your home? I know how to seal up cracks, etc.. but how to you eliminate the ones that made it in? Finally, please discuss the normal life span of this bug and how they multiply. Is the life of a stink bug as short as the 10-day life of a fly? Thanks.

Once inside, just vacuum them up and dispose of the bag. These rascals live a long time. Adults entering your home now will emerge in spring, move outside and lay eggs on plants. The young are called nymphs and they will feed for several weeks during the summer before molting into adults. In New Jersey, there was a single generation each year but in parts of China there may be five generations. We suspect that there were two generations in parts of Maryland this year. 

What is that smell?

Great question! To defend themselves against predators of troublesome humans they release a secretion from stink glands in their abdomen. The compounds in the scent include trans 2 decenal and trans 2 octenal. Here is the good part. Trans 2 decenal is also found in cilantro and many people find them to smell kinda nice. Let's add tomatoes and make some salsa. 

We have a log home in western Loudoun County and a big BMSB problem. I sprayed the outside of the logs with permetherin because I'd had some onhand, but it didn't perceptably reduce their numbers. One website that I've seen recommends a similar synthetic pyrethrin called cypermetherin for spraying the exterior walls of houses to control the BMSB. I've noted elsewhere that the mammalian toxicity of cypermetherin is (using a mouse model) higher than than to permetherin. Do you have any comments on the efficacy of cypermetherin as either a repellant or as a biocide for the BMSB?

The compounds you have mentioned are potent insecticides and I would not use them in the way you have suggested.  You may kill the ones present for a period of time but because they move long distances, there will be more. Also, as I wrote another guest, I am not sure that the label on the insecticide allows this use. Please be sure to read the label carefully and follow all precautions. Good luck.

I'm reading and hearing all about the stink bugs and as a new homeowner this is a bit scary. I've been seeing bugs VERY similar in shape/size but they're more a grey color. Are these the same? Also it says it's not harmful to humans but what about our caninie companions?

Unfortunately, they will return every year. Maybe not in these numbers but they are here to stay.

There were about 40 stink bugs on my outer porch wall. I had this nutty idea, that if I smashed a bunch of them with a trowel, their own stink would alert other stink bugs to a danger and scare them away. It seemed to work, as when I went out about an hour later, there were none. Science or coincidence?

You may have something here. We noticed the same thing in the field the other day while collecting them. Once they released their stinky odor, other stink bugs scattered. Keep up the good squashing!

Are they going to be coming back again next year? Or is this a one time thing?

Yes, they are here to stay.

The Do's and Don'ts has some good information for dealing with stink bugs at home, but what about in an agricultural setting? Farmers are reporting that they are doing massive damage to their crops... are there any organic or IPM-friendly ways to deal with these pests?

There is a huge amount of research underway to find new chemicals including organic ones to annihilate these buggers. Stink bugs are so infrequently a problem that they caught growers and the agrichemical industry by surprise. New products are in the pipeline as we speak and we hope to be able to do more next year.

Here in Potomac the stink bugs have been prolific, both outside and in. In the last several days the ones outside have almost vanished. Weather has been a lot cooler. Any relationship here, or are they all inside by now?

Great observation. They are now moving out of crops into wintering refuges. A little more rearranging is expected over the next two or three weeks and then thing should settle down...until late winter and early spring when they try to escape from your house.

I have two siamese cats that love these things. They will hunt them and then eat them. Is it harmful?

Gotta love those crazy cats. Mine has been doing the same with no ill effects. Maybe try to limit the diet to a few per day. Everything in moderation you know. Cheers!

I have read/heard that they are attracted to "white" so if you have white trim or white backing to curtains they are drawn to it. Is this true? I'm not going to redecorate just to eliminate them.

I have heard the same and while collecting over the weekend, I had my best luck on someone's white barn. I'm not redecorating my white trim either.

I noticed you said that they were "fresh off the boat from Asia." How did they end up all the way over here?

Please realize that as imports continue to increase in our great land there will be ever-expanding opportunities for stowaways like stink bugs, emerald ash borers, Asian tiger mosquitoes and such to arrive on our shores. This problem of invasive pests has grown exponentially over the past two decades and will continue to do so unless something dramatic changes.

Couldn't that get a little expensive if an home owner has a large problem with them?

Yep, it can get pretty pricey pretty quick. Some folks have purchase a shop vac to deal with this issue. Just dump them out in a large garbage bag and dispose.

I live in the Los Angeles area (specifically Pasadena, Calif.) and found stink bugs trying to get into the house yesterday, which happened to be the hottest day ever recorded. We checked all windows and doors and found them on the master bedroom's screened porch, the only windows or doors covered by a ceiling. Why do you think they chose only this area as an entry point?

These bugs are clever. They could have been escaping your glorious LA sunshine by hanging out in the shade. Curious observation.

What are Stink Bugs good for? How do they contribute positively to the environment? If I knew this then I'd know whether to love or to hate them, whether to gently move them outside of the living room, or to crush them and throw them in the trash.

Good is kind of a relative concept. If you asked all of the sea creatures in the Gulf of Mexico what good humans are, they would vote us off the island right now. But when talking about stink bugs, I'm hearing you. I love almost all bugs and usually just pick them up, take their picture and put them outside. In their native lands, stink bugs are fine, but in the US they are disrupting our ecosystems, harming our crops, and generally being a pian in the neck. I treat them with extreme prejudice and dispatch them when I can.

Any natural predators?

In the native range, yes. Some tiny parasitic wasps do much of the murder and mayhem in Asia. We know in the US they are attacked and killed by mantids, spiders, assassin bugs, spiders, and probably many more. They just don't seem to be able to stem the tide. They need help.

I first noticed these guys in my house in maybe June. I see them only occasionally and have yet to witness the odor. So, for the time being I'm much happier dealing with them than the Asian Tiger mosquitos that invaded a few years ago. Are the ones I'm seeing the advance shock troops, i.e., am I about to be overrun?

Hey Georgetown, Lucky for you these are mostly country bugs rather than city bugs for the moment. Keep your fingers crossed for this year and your eyes open for next year. Stink bugs could be coming to a neighborhood near you soon.

Do you personally conduct research on brown marmorated stink bug? If so, what are your projects? And if not, where do you obtain your information?

Doing research on these now pretty hot and heavy. Finding out what they eat in landscapes, what eats them and how to control them. I am also interested in their movement, defenses, and geospatial patterns. I talk to others, search the web, go to meetings with other bug geeks, read a lot , and make up stuff when I don't know the answer (only kidding). Thanks for asking. Cheers! Mike



Can plantings contol or limit bugs?

Perhaps, we know that they will move from some crops like corn and soybeans to surrounding areas. We know that they like to feed on some types or ornamental trees and shrubs like butterfly bush and maple but not on oak or sweetgum. There is some hope that we can help design landscapes that are stink bug resistant.

Are these a good idea? Should I deploy them around the exterior of my home to keep them from entering? Thanks!

I'm not sure how this would go down. Soapy water in itself will not keep them away. I'll bet if you knock them into a jar of soapy water, they will die, but it will be a very clean death kind of an immaculate extermination. 

When and how do stink bugs reproduce/lay eggs? What can we do to reduce their numbers next year?

They lay batches of eggs, usually 20 - 40, several times during the course of the growing season. If she is lucky and we are not, a single female can lay more hundreds of eggs each year. There is no known way to reduce numbers for next year. We are hoping that Mother Nature is on our side. Keep your fingers crossed.

I tried feeding one to my fire belly toads and they spit it back out twice. Then my room started to smell horrific. What eats these stink bugs in the wild?

Great question. See my current episode of Bug of the Week and you will learn how the wheel bug murders these guys. I have witnessed preying mantids, spiders, and predatory stink bugs killing these rascals. In their native land, the have many predators and parasitic wasps seem to be major players in control.

First, an observation. Even birds don't like the taste of stink bugs! We observed a Yellow Finch catching one mid-air, and then spit it out and spent much time wiping its beak on a branch. Priceless observation. We are invaded here in West Virginia...yet when inquiring with someone in Winchester, Virginia, told they've only seen 4 on their house. If you put out a wet bath towel overnight on the back of a lawn chair, you'll have hundreds in the morning to deposit in a bucket of soapy water. I find it rather gross, but it does attract the little devils.

Nice work and great advice. I love this approach.

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Michael Raupp
Dr. Michael J Raupp is Professor of Ornamental Horticulture in the Entomology department at the University of Maryland. His website Bug of the Week has tackled everything from assassinating bedbugs to mosquito control.
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