Elm Seed Bug

Many residents of the US are familiar with the box elder bug, an orange and black bug found on box elder trees in summer and found in homes in the late fall and winter as it looks for a sheltered place to spend the winter. True bugs that invade homes in summer in large numbers are uncommon. US residents may become familiar with a new species of red and black bug, the Elm Seed Bug, Arocatus melanocephalus.

The Elm Seed Bug was not considered a pest anywhere until 1999, when residents of Northern Italy complained about home invasions by large numbers of these bugs. The largest outbreaks of home invasions occurred in late May in the years 2001-2003. Every year since, invasions have been reported in different locations in Italy. Some evidence suggests that the home invasions are correlated to spells of unusually hot weather.*

Arocatus melanocephalus, the Elm Seed Bug

Like many Seed Bugs, the Elm Seed Bugs overwinter as adults, mate in spring and lay eggs on elm trees. The larvae feed on the fruits and seeds in May-June in Italy, and become adults in summer. Like most true bugs, the Elm Seed Bug has scent glands that produce a noxious odor, that deters predators. When crushed, the bugs produce an unpleasant odor.

Insects that invade homes in large numbers are prime candidates for global transport by hitchhiking in the baggage of travelers. Recently, the Elm Seed Bug has appeared in Southwestern Idaho. The bug is not expected to cause damage to Elms or have large ecological impact. Whether or not it becomes a nuisance or spreads around the US remains to be seen. The USDA/APHIS is asking the public in Idaho to be on the look out for this pest to help determine the extent of its spread.

Elm Seed Bugs Aggregate Indoors
Photo: mauriziano
http://www.naturamediterraneo.com


*Maistrello, et al. 2006. Journal of Thermal Biology. Volume 31, Issue 8, Pages 594–598.

About jjneal

Jonathan Neal is an Associate Professor of Entomology at Purdue University and author of the textbook, Living With Insects (2010). This blog is a forum to communicate about the intersection of insects with people and policy. This is a personal blog. The opinions and materials posted here are those of the author and are in no way connected with those of my employer.
This entry was posted in by jjneal, Invasive Species, News. Bookmark the permalink.

36 Responses to Elm Seed Bug

  1. Anonymous says:

    I live in Pacifica Ca. and have observed these bugs on my property in the past 3 – 4 years. I have not seen any this year. We only see a few at a time , less than 10, Ours are black and orange, we call them SF Giants bugs

  2. jjneal says:

    There are a lot of look alikes. You may be seeing large milkweed bugs or boxelder bugs that look similar.

  3. bob says:

    I have a large elm next to my house and have had a problem with these bugs for eight or nine years now. They get into the house in large numbers and are a real nuisance, but mostly on the side next to the elm tree. Can you tell me how to distinguish them from the boxelder bug? They are definitely not Milkweed bugs. My house is on the Russian River in western Sonoma County, CA. If these are indeed Elm Seed bugs, is there someone I should contact?

  4. Anonymous says:

    I live in Boise, Idaho and my house has been swarmed by this bug. I do not have Elms on my property but my neighbor does. If we spray the trees in the Spring will this help to control the numbers. I have been fighting the infestation for 3 weeks now and am about ready to move. I have sprayed the exterior three times which has helped keep the masses at bay, but they are still coming into my house-I guess through the window glides-even though I have sealed them as well as I can. Any other advice? Thanks

    • jjneal says:

      It is a new problem, so solutions are being tested. The vacuum cleaner is your friend.
      Bugs can crawl back out the hose so empty the bag or keep it closed so they cannot escape.
      An effective trap would be helpful.

  5. Vicki says:

    I also live in Boise and even in January, I find these bugs every day on my windows and flying around the house. I have bought a small shop vac just for the purpose of vacuuming up these pests- I put a small amount of soapy water in the bottom of the shop vac so they will drown! They leave their marks on the windows and the house siding. Why are they active even in winter? We have had a spell of very cold weather (-5 º F) and it did not seem to stop them at all. How are they staying alive in the winter since they feed on elm seeds?
    What is an effective trap?

    • jjneal says:

      Good idea with the shop vac. Their metabolism slows in the winter and they can go long times without eating.

      For some brown marmorated stink bugs, people cut the top off a 2 liter soda bottle and invert it to make a funnel into the bottle. Duct tape the top to the bottom. A cheap batter led light attracts stink bugs in the dark, like a closet or attic. I don’t know if it will work on these elm bugs.

      Soapy water in the bottom of the shop vac is a good idea.

  6. Vicki says:

    Thanks for your reply and the idea of the soda bottle funnel! I will try it.

  7. Anonymous says:

    I live in boise also and im having these bugs all over my residence

  8. M.E. Cole says:

    I am in Boise Id also and with this 110 degree heat the Elm Seed bug is working overtime! This may sound odd, but I have an older home that has an 2-4 inch area between the screens and window. I sprinkle the area with salt. This stops the majority from making their way in…although I don’t know the reasoning as to why. It also stops the ants from coming in. Obviously the smarter bugs simply walk up the wall and around the salt, but they are few and far between, not the huge numbers as before. One could try a window ledge if they have one. My bathroom used to get the most and this has stopped them completely! I am going to try to wipe down an area that I don’t care about it getting ruined with heavy salt water to see if that will stop them from coming in at an area where there is no ledge to put the salt.

    • jjneal says:

      Hopefully the salt doesn’t rust or corrode your screens. The screens without the salt may be effective. Ants often forage indoors early in the season but then stay outdoors when more food is available. People over estimate the effectiveness of ant treatments as a result.

      In the Midwest triple digit weather last year, insect activity was depressed in the really hot weather. The bugs like air conditioning, too!

  9. I live in Boise, too. The hotter the weather — the more of these bugs I find in my house! I thought this year they had moved on — didn’t see any of them. Alas, we hit triple digits, and they are trying so hard to get into the house — what is gross is that they will hide behind picture frames and under items on the floor (my sons’ remote control car, for ex.) — they mass there. Yuck. We have put dimataceous (sp?) earth at the corners of the doors and in the window tracks — the old house windows are an easy way in. Hate them! Any other advice for getting rid of them is much appreciated!

  10. Sarah says:

    I have them at my house in Boise, Id too- Never had a problem until today. I am pretty sure I accidentally let them in yesterday when I went outside to water plants and had not completely closed my screen door. This evening I have killed about 50 of them, and they keep showing back up in groups of 3-8 of them, crawling around the ceiling near my ceiling fan. Makes me feel like they are hiding in the hardware and coming out when I remove/flush their friends. Quite gross. Disappointed that until yesterday I never had a problem with these pests, but then again- it’s been over a 100 degrees for five days and they are trying to escape the heat! The article I have included below also recommends the shop vacuum with soapy water. We are two years new with these invasive species from what I read (Elm Seed Bugs new to the US, found in Idaho during the summer of 2012), so I think there may be a learning curve in removing them otherwise. Best of luck and please share any secrets you have! Too bad a fly strip or other attracting mechanism isn’t available to gather them! http://www.kivitv.com/news/local/198825511.html

  11. David Williams says:

    I live in Nampa, Idaho surrounded by Elm trees. I have these bugs in mass quantities. Been using the shop vac, my friendly spider bros who hang out in corners, and used a can of old insecticide I had from a couple of years ago..it dropped them very nicely. I thought it was Raid Ant and Spider..had a brown plastic lid. I am kicking myself for tossing the empty can, because the next can of Raid Ant and Roach I bought did nothing and I am unable to find what I thought I had used last. They are attracted to light so I have white LED night lights near the spiderwebs and they seem to be going there and becoming spider food. I will try the pop bottle trap too.

  12. bob says:

    i live in Boise with an elm three in the back yard. these bugs are every where .i found that a mild dishsoap and water solution stops them in their tracks but i have to keep doing it every day they keep coming!i like the vacuum idea and i wil try the diametrious eath thing too.

  13. Jim says:

    I am also a Boise resident with the Elm bug problem. It is now late February 2014 and I’m already finding a few bugs around the house. Our house is old with aluminum siding covering original wood siding and a few old windows. It is really hard to seal an old house per instructions. And they seem to get through new vinyl screened windows too. They also have gotten into attic vents that I don’t want to block or seal. It would be helpful to post a summary of what works. Does spraying bugs outside on your house with soapy water kill them? Do you know if birds are attracted to them? I would not use a bug killer spray if it results in killing birds that eat poisoned bugs.

  14. jjneal says:

    They will get hungry and leave in the spring. You might contact Idaho extension to see what they currently recommend for control. Brown Marmorated Stink bugs can be captured in light traps. Cut the top off a 2 liter soda bottle. Attach a battery operated LED light to the inside of the bottom. Fit the top as a funnel leading into the bottom. Duct tape it together. Placed in a dark attic or a dark room it attracts Brown Marmorated stink bugs. It may work for elm seed bugs but I have no reports. It may be worth a try.

    • I live in Boise and I am going to try this! Thanks for the tip.

    • Marie Cole says:

      Boise resident here and Idaho Extension didn’t have any ideas either since any insecticide used had to be directly applied to bug and even then many were useless. So, this brings me to your trap. I think I missed something. What prevents them from just crawling back out? And the Elm Seed Bugs I encounter mostly seem to come in at night when it is dark. They especially like my bathroom widow so I thought it was due to the humidity level. I don’t have the same issues around any of the other windows or doors I have here. I don’t have the attic invasion like some do. Last year I stopped a majority of the bugs from getting past the window seal by using sea salt and water mix sprayed daily on the inside and outside of the frame as well as sprinkling some salt in the corners I thought they might be getting through. Someone was concerned about the damage this would do to the wood (which is what I have since it is an old house) and it didn’t hurt it. I suppose those with metal or aluminum would have to reconsider this method. At least I wasn’t finding the bugs hidden in my shower curtains, or falling from my towels when I moved them or dropping on my head when I walked in in the mornings! One more interesting note is I have a window/screen in my bedroom door that does not have a tight seal at all and rarely do I find an Elm Seed Bug here, so again I am wondering if it isn’t a moisture issue? On the contrary I do know they do not like direct water since they attempt to “fly” away from any wet spray and huddle in when attempting to wash them down the drain. There has to be some sort of level they are seeking. Anyway…just my two cents.
      Good luck everyone!

  15. elisa says:

    They are terrible this year all over! Has anyone tried one of those bug zappers? With the purple lights? I was wondering if that’d help any.

    • Gary says:

      I tried the soapy water that I heard about and it definitely kills these elm seed bugs on contact, I’m not sure there is a residual effect though. I plan to run this through an old bottle of weed and feed that you hook to a hose and spray my entire house down.
      I used dawn dish soap and hot water, doubting that the temp of water has much effect as I believe it’s more the soap that clogs the bugs ability to breath, since most bugs tend to breath from the sides of their body. The soap must clog these respiratory openings causing the bug to suffocate.

    • Jerry says:

      In Mountain Home here I have a 1.5 acre bug zapper not one elm seed bug in it and the shady side of the house is covered with them the only thing i have found is spraying around doors and windows is with military grade mosquito repelant

      • Jimmy Smith says:

        The recent heat has driven the bugs into the house. I keep a spray bottle of diluted Dawn around all the time and that appears to have some lasting effect. I intend to pressure wash the areas they like with Dawn. We live in the city of trees in the north end in an old house with aluminum over old wood siding and it is hopelessly vulnerable. Seed clean up in laughable. The trees product pounds of seeds that blow everywhere.

        Do these bugs have any natural enemies besides human? How do people live with these bugs in areas of the world where they are native and have more experience?

        On Thu, Jul 3, 2014 at 9:42 PM, Living With Insects Blog wrote:

        > Jerry commented: “In Mountain Home here I have a 1.5 acre bug zapper > not one elm seed bug in it and the shady side of the house is covered with > them the only thing i have found is spraying around doors and windows is > with military grade mosquito repelant” >

  16. Gary says:

    I have a camper down elm tree aka “umbrella elm” and have had it for 15 years+ I have never seen this bug on that tree! This bug infested us 2 years ago we are now on the 3rd year of infestation. I can’t believe they come from my particular elm tree maybe a different variety of elm? My neighbor has the same or more in numbers than we do but we both want to eradicate them indefinitely. If anyone knows of a solution we would love to hear it please.

  17. jarod knapp says:

    these darn elm bugs are on my hit list! I kill as many as I can any way any time any were. I smash them, I drown them, I poison them, I burn them with fire!!! I’m going to clean up any tree seed area I’m aloud to! they are smart and fast like little ninja’s avoiding me killing them! dropping, running, pretending to be dead, flying! landing on me none stop in some places. how do I do yard work, cleaning, weeding, mowing grass for my elders with out getting mad at these darn elm tree bugs… this means war!
    Think and plot on these bugs. make plans to take any tree seeds out of the equation the best you can. kill there nesting area’s many times over again till they are all obsolete!!!
    strongly dislike tree bugs, all of them. skeet skeet skeet!!

    • Anonymous says:

      They are so bad out here in Middleton, Idaho!

      • Anonymous says:

        I’ve found that Lysol spray or 409 seals barriers and practically stuns them dead. Hit up ur local zamzows I bought a $20 jug of this stuff they said kills elm seed bugs inside and outside. So far the combination of the three periodically seems to be dropping this annoying little bastards!

  18. Roberta says:

    I live in Nampa and we are having a big problem with these pests this year. Only found a few in the house last year. This year I’m killing 20-30 a day.

  19. Kelsey says:

    I live in an upstairs apartment here in Payette Idaho, an omg my apartment is being over taken by these elm bugs. A pest control guy came out the other day said it is there mating season an there is nothing you can do. I did have my maintance man spray some type of bug killer on my back porch an it has seemed to kill them so far, but oh my word i just swept my kitchen an i must of swept 100 of them up, there out of control. someone help me how can i get rid of them inside.

    • Gary says:

      Sorry Kelsey, there is no cure except time. We are on our 3rd year of these pests and the only thing I have found to kill them is dawn dish detergent but it only works on contact nothing more! I’ve noticed once they come inside they seem to die in a shirt time then you vacuum them up, beyond that you just wait for the heat to subside and they seem to go away.

  20. Marie Cole says:

    Check and plug as many entrance areas as you can; Ask your landlord to caulk your windows and door seals. I know it sounds deadly but for awful infestations, a daily insecticides spraying around your doorways might help. Make sure the aren’t coming in through your vents! If they are you better be talking to that landlord again! Before you, your guests or any pets enter your home brush off head to toe and don’t forget to check the bottom of shoes/feet. Don’t squash as the Sent supposedly brings more! Hope this help!

  21. CAL says:

    I too live here in Boise & these little devils are in full force again for the third year. No solution yet but not ready to give up the house to them. We use liquid laundry detergent mixed with water in a spray bottle and that is a way to kill them if they get contact with the solution. The battle can be discouraging sometimes. We found that they were coming down the chimney in droves so we built a fire one evening with the AC running and burned them out good. Sat there with a vacuum and sucked them up as they ran out the front of the fireplace. Biggest thing that I found is that we needed to cut all the trees away from the house because they traveled through the trees to the house. Even though the trees are Maple trees that are around the house. Cannot find their specific entrance yet as they are smart and run or fly when they hear me and the vacuum. Have a video camera setup today to see if I can find out more specifically where they are getting into the house at. We use clear packaging tape to seal doors & windows that we feel they are passing through but then we cannot use those doors or windows any more. Be careful that you don’t seal the good air out of your house and end up with a carbon monoxide problem. We need to find out who their natural enemy is and get rid of them that way. Unless that bug is even worse!

  22. Anonymous says:

    Thanks for all the information, I talked with my Garden Center and they suggested Sevin spray, however I have been using Sevin powder for earwigs and it hasn’t harmed the Box Elder Bugs. I have 3 silver maples in my yard. I will try the soap and water as I don’t want them in my home, so far I haven’t seen any inside but outside they are always there mating. I live in Carson City, NV so I guess it is an all over problem. Thanks for all the information.

  23. Anonymous says:

    I live in Nampa, ID as well and have two acres with many many Elm trees. We have had horror-story level problems with them coming down our chimney, or in the camper trailer my dad lived in for the past 3 or 4 years. Last year (2013) I cleaned up all the seeds I could in the spring and we thought the bug problem was a tad better than the previous year. I also used diatomaceous earth, malathion, raid flying insect spray, soapy water, bayer tree and shrub insect control—nearly everything we could think of—all of these things work well—but the bugs just keep coming by the thousands. This year, I didn’t get out to clean up the debris and spray malathion early in the year when the bugs were still miniscule red dots, and the problem was worse again this year. I think we will take a good number of our elm trees down this year, in addition to treating some of the ones that are left (particularly around buildings) with the bayer systemic treatment this coming September, like recommended. They are definitely worse on structures that are right under a tree. I treated the tree over our deck last year and noticed a marked improvement on just the deck area, but they are still everywhere–and we have tons of trees we don’t want to cut down. And Bayer insect control is NOT cheap, so we have to select just a few trees to treat. We also bought some removable caulk to caulk all the storm windows, and even the few new vinyl windows we had installed last year. I vacuum a lot, but when I don’t have time to get a vacuum out, I grab a couple of inches of tape (any kind–masking, duct, packing) and lightly press the tape on the stray bugs so they stick, then fold the tape over so they don’t squish—so we can avoid the stink. The whole family has spare rolls and pieces of tape handy in their areas, so we can get get rid of the onesie-twosie bugs everywhere. OH YEAH—we got chickens last year and a few of them absolutely love the bugs. We put them in our woodshed every morning and they eat tons of elm seed bugs by the hour–then turn the bugs into protein-rich eggs! We’ve talked about getting about a hundred more chickens to help us. It is definitely a constant battle. The kids have named one particular chicken “Vacuum” because she loves elm seed bugs so much and is so quick at pecking them up before they can run and hide.

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