Eastern Boxelder Bug

2008 November 8

S_ found this one in the yard on November 6, while out playing with Sam. “I think it’s a boxelder bug” she said. And so it is – the Eastern Boxelder Bug, Boisea trivittata.

These are very common and very widespread, and a lot of people are familiar with them because they are very visible, what with being mostly orange and all.

They are another of the bugs that drink plant juices, with a long piercing-sucking stylet for their mouthpart.

They have pretty decent eyesight, and red eyes.

They like juices from maples and ash trees in general, but they prefer to lay eggs on box elder trees. If this was all they did they wouldn’t get much attention, because the box elder is not of much economic importance – they are fast-growing, kind of scrubby trees that aren’t much good for lumber, and have only a little popularity for things like hedges and ornamental plantings. Boxelder bugs usually don’t actually do visible damage to the trees, even in the years that they become very numerous.

Yet again, the orange color is a warning to birds and other vertebrate predators that they aren’t good to eat – they are reported to smell bad when crushed, and probably don’t taste good to anything that has a sense of taste. They evidently aren’t actually toxic, though, and so predatory arthropods like spiders and assassin bugs are willing to eat them.

We don’t have all that many of them around here, probably because box elder trees are not tremendously common in this area. Elsewhere, though, they can breed up to very large numbers. This isn’t noticeable most of the year, but in the fall the adults look for a good place to hibernate over the winter. Before human-built houses were available, they liked things like small caves, tree hollows, and rough bark. Nowdays, though, houses are the places that look best to them, and they like to crawl under siding and get inside the house. As a result, people tend to freak when their houses get invaded by these bright orange bugs that get into everything, and leave foul-smelling stains on rugs and fabrics when they die. Of course, once they are inside the house, it is kind of too late to deal with them other than by vacuuming them up and hoping for the best[1]. Some companies sell pesticides, but really, if you kill them inside the house, then insead of live bugs in everything, you have dead bugs in everything, with the added bonus of pesticide residues. The best approach is preventing them from getting in the house in the first place, by sealing up cracks and openings in the house. In extreme cases, it might be necessary to get rid of box elder trees nearby. They mainly breed on the female box elders, so those are the ones that really shouldn’t be allowed to grow next to the house.

So, anyway, if the adults get through the winter without being vacuumed up by an annoyed homeowner, then they fly off in the spring to lay eggs on a convenient box elder tree, where the nymphs hatch out and feed on the developing seeds before going on to other things.

[1] The “vacuum them up” method actually works pretty well for a wide range of insects in the house – flies, mosquitos, boxelder bugs, lady beetles, etc. What we use is a little hand-held vacuum (a Dirt Devil “Scorpion”) that cost about $20. Just go around the windows and walls once a day and suck them all up, and voila! Ours has a little flapper inside that keeps the critters from crawling back out again after it is turned off. It’s probably a good idea to take it outside and empty the little bag immediately afterwards, though. Something that is *most emphatically NOT* a good idea, is spraying bug-killer down the vacuum hose. Bug killer sprays are generally very flammable, and this is very likely to result in your vacuum exploding, so *don’t do it!* Not to mention that, even if you were to be phenomenally lucky and your vacuum did not turn into an expanding ball of flame and shrapnel, it would still be exhausting bug killer all over the room.

9 Responses
  1. November 8, 2008

    Very interesting. My neighborhood always sees a big influx of these things every year, usually in the late summer. I’ve always wondered what they are. And now I know.

  2. November 8, 2008

    We have their first cousins out here in the west (AZ mountains, to be specific) and I came across an interesting swarm site last year:


  3. Lon permalink
    November 10, 2008

    My co-workers learned the hard way not to squash them. They leave orange-red stains.

    Since all they do is wander around harmlessly, I never saw the point of squashing them

  4. November 11, 2008

    Back when I was in high school, it was believed that boxelder bugs are what cause the striking red/pink stain in boxelder trees. People believed that the bugs got into the wood (not sure how), died, and left the pink stain.

    Now of course, we are all a little smarter and know that its the tree itself that causes that color. But things were so much simpler when we could just blame (or thank) a little bug!

  5. November 13, 2008

    They are out and about these days, aren’t they? I just put up a few pictures of one, too. Great shot.

  6. G ANDERSON permalink
    February 10, 2009


  7. anthony permalink
    August 6, 2009

    get these discusta bugs out of my house im going crazy please help me!!!!!

  8. brenda Jo permalink
    October 26, 2011

    when I was in ND, I saw these bugs in masse for the first time. I got clues from neighbors to place a bay leaf on the windowsills, cuz they don’t like them. It seemed to keep them out of the house!

  9. brenda Jo permalink
    October 26, 2011

    When I lived in Montana, I worked at a baitshop/gas station that also had cabins you could rent. One year there was a huge fish tournament going on at the same time as an all school class reunion. Real small town, not alot of motels, and the cabins had been rented a year ahead of time. One couple traveled clear from Florida, got there about 10:00 pm, pooped, and just wanted to crash in the cabin they rented. As I was closing up the store, they ran in to tell me the cabin was infested with cockroaches!! I knew we didn’t have those critters in the area, mainly ‘cuz it’s too flippin’ cold there in the winter, but they insisted! They wouldn’t stay there, and because of all the folks in for both doin’s, no place to stay less than 250 miles away! I felt so bad for them, but seein’ how they were from Florida, I couldn’t understand how they could not know the difference ‘tween a cockroach and a boxelder bug! Come to find out, those buggers would head back to that very cabin every year, and there was a buttload of them! I wouldn’t have been able to stay there, either!!! Even tho it’s close to halloween, this DID really happen, and I wonder if they are still fillin’ that cabin even as I write this!!!

Comments are closed.