WHAT’S IN YOUR ATTIC? BROWN MARMORATED STINK BUGS, PERHAPS

By Arthur V. Evans

Last month, while attending a meeting of the Bull Run Mountains Conservancy held in The Plains, Virginia, I was approached by several members who wanted to know about a stink bug that had invaded their homes by the dozens or hundreds in the fall. At first I thought they were referring to a species of bark stink bug, Brochymena, which sometimes enters homes by hiding under the bark of firewood hauled inside for the fireplace. Just as I was going into my spiel about sending me a photograph or a specimen for identification, someone said, “Look! There’s one!”

 

The brown marmorated stink bug, Halymorpha halys Stål, is steadily expanding its range across North America.

 

Sure enough, a robust gray stink bug was slowly making its way up the wall toward a window through which the day’s last rays of sunlight were shining. Judging from its distinctive markings, I knew that it was not a species of Brochymena and wondered if it might be the brown marmorated stink bug (BMSB), Halymorpha halys Stål. My suspicions were soon confirmed.

This uninvited insect from Asia has proven to be quite a nuisance to many homeowners in northeastern United States for the past several winters. They are much more likely to take up residence inside buildings than either of their native look-alikes, Brochymena and Euschistus.

BMSB was first reported from Allentown, Pennsylvania in 2001, but it turns out that the species has been in that area since at least 1996. The very first individuals probably arrived in America as stowaways, possibly as eggs, on packing crates most likely shipped from China or Japan. Since then, they have spread throughout Connecticut, Maryland, New Jersey, New York, Pennsylvania, Virginia, and West Virginia. As of 2004, an isolated population has become established in Oregon.

Like other stink bugs in the family Pentatomidae, BMSB are “shield-shaped” in outline. They are about 17 mm in length and are nearly as wide as they are long. Unlike similar species of native stink bugs, BMSB has white bands on the antennae and dark bands along the edges of the abdomen surrounding the wings. The head and pronotum (upper surface of the mid section, or first thoracic segment) have patches of small, round coppery or metallic bluish pits. The glands that put the stink in these and other pentatomids are located on the underside of the thorax and upper surface of the abdomen.

 

A nymph of the brown marmorated stink bug, Halyomorpha halys.

 

Brown marmorated stink bugs probably produce a single generation per year in America, but records from the sub-tropical regions of China indicate that there are 4-6 generations annually. Local populations of adults emerge from their winter hideaways in early June and begin mating and laying eggs almost immediately. The small black and red larvae (nymphs) soon hatch and molt five times during the months of July and August. Adults appear in mid August and begin seeking overwintering sites by mid September as the evenings start to become cooler.

To escape the cold, BMSB enter homes, out buildings, office buildings, and other structures by crawling under siding and shingles, around door and window frames, and into crawl spaces and attics. Once inside, they will settle in and become inactive for short periods. However, reinvigorated by the warmth of home heating systems, they are driven to crawl over walls and furniture, or fly clumsily to lights and windows.

As they bumble about, BMSB leave their odor on everything they land and crawl on. The accumulation of this odor at a good hibernation site serves as a powerful chemical beacon that attracts their brethren to the same location year after year.

The best way to keep BMSB out of homes and other structures requires preventative measures to be taken during the summer, after the bugs have already left, to prevent a re-infestation in the fall. Seal cracks and spaces around doors, windows, vents, utility access points, siding, trim, fascia boards, and chimneys. Caulk is handy for small cracks, but wire mesh and screens may be required when dealing with larger spaces associated with attics and foundation vents.

The good news is that once inside your home, BMSB will not bite you or your pets, spread disease, nor lay their eggs. Their piercing-sucking mouthparts are adapted for drawing sap from plants, not damaging furniture, clothing, or other household items.

Using insecticides on BMSB indoors is not particularly effective. Crushing them or sucking them up with a vacuum cleaner causes them to release their noxious odors that may persist in a room or on cleaning implements for sometime. Any disturbance perceived by the bugs as a threat will cause them to stink as a defensive measure. The best thing to do is to simply let them walk on a piece of paper and take them directly outside.

What is being done about BMSB nuisance in America? Since they have yet to become serious agricultural pests here in the States, there is little incentive for chemical companies to develop pesticides to combat them. Pesticides of any kind are incredibly expensive to bring to market and the number of homeowners plagued by home invasions of these bugs will never support the company’s efforts to recoup their investment, much less generate a profit.

But all is not lost. Researchers are learning everything they can about BMSB so that they can identify the weak links in their life cycle and exploit them to affect some level of control. Select BMSB genes and proteins are being sought for the possible development of genetically modified crops that will help suppress their numbers. There is also the possibility of using parasitic insects that will attack stink bugs during egg stage, not only to lessen their potentially harmful impact on crops such as soybeans, cotton, and corn, but also to reduce the numbers of individuals seeking shelter for the winter.

One of the more promising avenues of research involves the synthesis of attractant chemicals, or pheromones, to use in stink bug traps. Although BMSB attractant pheromone is currently unknown, scientists have discovered that they are attracted to the pheromones produced by the male of another species of stink bug native to Japan, Plautia stali Scott. Traps in America baited with this pheromone not only attract BMSB, but also some native species of stink bugs and a tachinid fly, Trichopodes pennipes,  that parasitizes native stink bugs.

Why would these stink bugs and one of their natural enemies be attracted to the pheromone of another species of stink bug? Research on other stink bugs species suggests that some use the pheromones of stink bug species other than their own in an effort to locate better feeding sites. Further, this chemically induced aggregation of different species of stink bugs may serve as a defensive strategy known as the “selfish-herd effect.” As the herd, or aggregation, grows individual stink bugs are increasingly less likely to be selected by a parasitic fly that, not so coincidentally, uses the very same pheromone to locate its victims. The discovery of the attractiveness of this pheromone offers up a potentially useful tool for monitoring and managing BMSB in America.

BMSB is steadily expanding its range across North America. Although clearly annoying to homeowners, the degree to which this species will become an agricultural pest in America remains unclear, especially as it moves south into warmer climates. Within their native range of China, Japan, Korea and Taiwan BMSB is most certainly an agricultural pest, attacking soybeans, apples, peaches, figs, mulberries, citrus, persimmons, and a variety of ornamental plants.

For now, all we can do is batten down the hatches and hope that science will come to the rescue.

© 2010, A.V. Evans

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35 Responses to “WHAT’S IN YOUR ATTIC? BROWN MARMORATED STINK BUGS, PERHAPS”

  1. Ca n anyone tell me why they sound so loud.

  2. James Benoit Says:

    Dr Evans,
    I want to build the trap i found online from the University of Florida. Do you have a source for a pheromone? I have also read that pear ester may work as an attractant. The BNSB are out of control in my area of SE PA right now. Spraying the exterior of the house is a waste of time and who knows what else I might be killing! I appreciate any help.

    • I am afraid that there is little to be done at the moment in terms of controlling the adults. Here is a link that provides a few tips for control:

      “Dr. Art Evans, entomologist” is on Facebook.

      • What is the link that offers tips for controlling the stink bugs? I have them in my attic. I have tried freezing them and that did not work. Later this week I have an exterminator coming but it sounds like there is little for them to do.

  3. I just went on a stinkbug killing spree of 17! Yesterday I killed somewhere around twelve

  4. Jon Robinson Says:

    I found the best way to kill every SB in your home is to turn off the furnace including pilot fires to stoves and water heaters and open all the windows in the home. Every SB will die within seconds when the temperature in the home reaches approx. 30 degrees fahrenheit.

    • A very practical approach to the problem!

    • I had thought of this and may try it shortly. I have a Lindal Cedar home with lots of wood trim inside and they are imn there by the hundreds! They fly into your hair, your plate while eating, glasses while drinking and any lamp that is turned on. It’s just awful. Wondering if the low temps will infiltrate into paneled cielings and so forth. May have to leave it open for a day or two.

    • I am sorry to say that this method won’t work! I had high hopes that it would, but before risking freezing our water pipes I tested it out by putting a live stink bug in a plastic container & put it outside where it was under 30 degrees. The SB immediately went belly up and I thought, all right!! But then I brought it in the house, and it warmed up and came back to life. Tried again, this time leaving it out in the under 30 degree air for an hour and 15 mins. Brought it back in, and…it’s crawling around inside the plastic container after 5 minutes in the warmth. …sigh….great idea, Jon, but these bugs are tougher than that.

      • Most bugs probably dig in when it gets cold, but I thought at least a few of them would drop to the floor where they could be easily picked up and dispatched!

        I don’t know about this species’ ability to survive sub freezing temps. Even if they were to succumb it would probably take an exposure of 24 hours or more at temperatures well below freezing. Insects freeze to death by ice crystals forming from water in their tissues that expand and shred those tissues.

  5. My home is totally invaded by these menacing bugs! It’s February and I still kill at least 20 a day throughout my house. I’ve sealed up every crack as best I could but they still find a way in to the living space from my attic (I assume thats where they are hiding). The article mentioned that BMSB will not lay eggs in the house, but it sure seems like they are. While i dont see any eggs, I constantly find “baby” or very small stink bugs along crawing everywhere. We seriously cant take it anymore!

    • Sorry to read that you are having such problems with BMSB. They have been a real nuisance for people this year. I wonder if the smaller bugs that you are finding in the house are something else?

      • I also have been finding these bugs that i believe to be nymphs. A while ago before the BMSB became so abundant i saw a few of these little bugs which at the time i believed to be ladybug nymphs due to their roundish shape and spots on their back. However after looking up pictures of the nymphs of both now i believe them to be the nymph of the stink bug and they are abundant in my house especially my curtains. When i spray Raid on my windows I find a dozen or so of these bugs. Also i have read they they can’t breed indoors but the constant finding of these bugs i believe to be nymphs seem to disprove that. I have washed and sprayed my curtains several times only to have these little bugs come back to gather on the backside of them after the pesticide wears out.

  6. Harry Kramer Says:

    Questions: is the use of pheromone in an indoor trap safe to use?. Also, where can it be purchased?

  7. I love my vegetable garden and over the past couple of years I have noticed a tremendous increase in a variety of different stink bugs in my garden. I am fustrated with the damage they do to my plants and I hate to use any insecticides, etc.. So my method has always been to walk through each row picking off the stickbugs and placing them in a mason jar of bleach water, I put a lid on the jar and the bleach desolves them. I reuse the same jar all season long. However, this year we are expanding our garden, and that has me researching other options for trapping them.
    I too have read the UFL report and would love to build the traps for my garden but they fail to explain how to accuire the pheromone needed to lure the bugs into the trap.
    If anyone else knows please could you give the rest of us some guidence. I know that there are other types of pheromone lures that can be purchased, such as those from Johnny’s Selected Seed (http://www.johnnyseeds.com/c-478-lures-and-traps.aspx). They have a corn earworm pheromone lure and a cucumber bettle pheromone lure. Are these different? Is it possible that these would attack stink bugs?

  8. Dr. Kathy Falkenstein Hood college, Frederick MD Says:

    Dear Dr. Evans,
    I am writing a lecture on endocrinology and wanted to add a bit about pheromones of brown marmorated stink bugs since they are a BIG problem in Maryland. In fact this weekend my husband bought a trap with the pheromone in it and it has not attracted one stink bug! I am questioning if a pheromone will be effective if the stink bug is not in their mating mode? I would appreciate a quick response if possible because I am lecturing on this tomorrow – Tuesday Sept 13th, 2011! Thanks,

    • Interesting question. I can only speculate that this time of year that BMSB are probably more focused on finding a warm spot to spend the winter rather than mating and therefore would show little interest in sex pheromones. However, I have read that they home in on an aggregation pheromone this time of year to locate an overwintering site, but this is not what is currently being used in BMSB traps, but rather that of another stink bug species that is mildly attractive to BMSB.

    • Sorry that I did not see this in time for your lecture. Aggregation pheromones are not necessarily sex pheromones. Until the pheromones are sorted out, the best BMSB traps I have seen thus far involve lights.

  9. Peggy Padovano Says:

    Our experience has been that they do make noise. My husband was sleeping in his chair and one made a noise which is how we knew if was there. I find them as disgusting as cockroaches, only difference is you can kill a cockroach with insecticide. Last year my daughter’s bedroom (in the attic) stunk like sulfur from them. She had to move down and sleep in the living room. Someone please come up with something quick!

  10. Its almost February in Mid-Coast Maine where we recently had warm temps (above freezing) and I’ve found two of these in my house.

    Unfortunately I crushed one before reading the article and they do stink! Hopefully when we replace our roof this summer we can seal it up tight as they are in our attic.

  11. I have found that this trap works very well indoors. It combines an “attractant concentrate” with water and an LED lt base. Coworker of mine placed it in his attic and dozens of stink bugs in the trap within hours. Video is about 60 seconds long
    http://youtu.be/WySi5o2dWVI

  12. Mike McIndoe Says:

    I freakin hate these things! I first saw them appear last fall of 2011 when my dad had his garden up. I see like 20 red-backed stink bugs in the window holder and I was scared to death. I found out they don t bite so I sucked um all up and put them outside, Thought I was free of them, but here the freaking come in January with brown backs! Now its late april and I seeo ne pop up at least every time I come up here to my attic. How DO they get in here…really? I taped up my Windows hard and my dad wont help me put in the air conditioner yet. How can i get them to stay AWAY from my attic where all of my videogames are cause my guests are complaining about the smell and its annoying and emberrasing. And my parents are not doing JACK! Please help!! :'(

  13. Interesting article – I was wondering about this insect as a friend is dealing with it in her home -

  14. Peggy Padovano Says:

    Still no solution? Companies like Terminix are advertising they kill stink bugs. How are they doing it?

  15. found my first stink bug in a poinsetta I brought home! I hope it is the only one!!!!

  16. These things are horrible! It’s like they’re aiming for me when they fly around my house. Last year I tried a trap my friends gave me though, seemed to work pretty well thank goodness, they hated coming over. I found the web site, it’s indoorstinkbugtrap.com, hope this helps!

  17. We are about to have two days of well below zero temps in Pennsylvania. I sure hope it does something to reduce the population of these menacing freaks. It is incredible how resilient they are.

    • Has ANYONE found ANYTHING that works? These things are giving my family nightmares! I have been spraying them with hair spray and then flushing them down the toilet. I have cut down trees, removed window planters and other plants from the front of my home, doused all flood lights and still they get in. Very frustrating

  18. Peggy Padovano Says:

    This year I took the air conditioners out of the windows early and closed the windows. I took away my window planters and all plants near the door. I keep the lights out in the front of the house at night since they are attracted to light. I hate to say it but so far this year I’ve seen two – both of whom I flushed down the toilet.

  19. how do i get rid of the stink bugs just killed four what look to be full grown. they are in my attic which is a finished attic please tell me what to do. thanks

  20. We have had a stink bug problem for a year now in our attic, I have killed many and there never is an odor. Could we be dealing with another type of bug? We have also used 2 stink bug traps and have not caught 1 bug in them.

  21. Try a cookie tray in the floor with a bug zapper on the tray. This tray catches the dead bugs and use it at night away from your bedroom because the zap is noisy. Plug it in at night when its dark before bed. Dont leave it unattended and clean the tray frequently because although i have never heard of this a pile of them could catch fire if you had 100s in the tray. But thats what the tray is for.

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