Black and Yellow Longhorn Beetle

2011 April 30

When Sam caught this beetle in July of 2010, I just took the pictures for the sake of the practice, because I though that it was one that had already been photographed and posted on this site. But, on further examination, I see that aside from both being black beetles with yellow markings, they were not otherwise very similar. The other one had very thin, sharply curved yellow markings, while this one has broad yellow stripes, with the middle stripes joining to make a kind of “U” mark on each wing cover.

This looked fairly distinctive, and after some rummaging around on BugGuide, it looks like one of the Flower Longhorns in the genus Typocerus.

Specifically, I think it’s Typocerus sparsus, which is evidently specifically found in the Great Lakes region. In which case, it is as close to a species endemic to this area (that is, found here and nowhere else) as we have caught to date.

Like other non-wasp insects that hang around flowers and have black-and-yellow markings, these beetles are almost certainly wasp mimics. As usual, it is believed that they are trying to convince potential predators that they are packing a sting. As far as anyone knows, they are actually harmless. But after finding out that even some insects that are commonly believed to be simply mimicking other, more dangerous/distasteful insects are actually dangerous/distasteful in their own right, I’m not so sure I believe that these are completely harmless without some evidence. Unless somebody tastes one of these beetles and declares it edible, I’m going to suspect that there is a good possibility that they have some nasty chemical defenses themselves. Or at least are able to give a nasty pinch.

That said, they do look a lot like wasps when they fly, so anybody who reflexively avoids wasps will probably shy away from these beetles in flight, too.

Like other longhorn beetles, their larvae bore into decaying wood, although I don’t think this particular species has been studied enough to know their wood preferences. Their relatives seem to like rotting pine, though.

Note added on March 13, 2013 for readers in the Southwest: With the number of people commenting below that they found a similar beetle in Texas, and that they got a painful sting/bite from it, I figured I’d better look into this.

In general, beetles that look like mine really are other, related wood-boring beetles. And if they seem to be associated with firewood, then that’s almost certainly what they are. But, in the southwest, another possibility is this similarly-colored blister beetle, (although they are not closely related). Blister beetles have a strong blistering agent (cantharidin) in their “blood”. When they are crushed, or feel threatened, they will bleed this on you and apparently raise painful blisters. They are very toxic if eaten, too (some blister beetles have been known to kill horses when they got baled up into hay that the horses then ate).

So, if you live in or near Texas, and see a beetle similar to this, don’t handle it, and don’t squash it. And definitely don’t eat it!

34 Responses leave one →
  1. April 30, 2011

    “(T)hey do look a lot like wasps when they fly, so anybody who reflexively avoids wasps will probably shy away from these beetles in flight, too”

    I wonder what the acquistion, identification and targeting algorithms look like in beetle predators. Let’s use birds as an example, though they might not be afraid of wasps.

    Apparently, they have a decent sensor array.

    The “Scientific American” magazine recently had an article on the vision of birds.
    They presented evidence that the range of light that birds can detect extends significantly into the ultraviolet range

    Light perception is one thing, resolution is another. Beetles that look like wasps might get away with the ruse if the bird’s matched filter detection is based on “small, flying, black and yellow blob.” Then you’d have to wonder if the birds could discern flying styles and use that for further identification – straight and slow vs. zig-zag and quick. I would bet that they use the image for target identification and the flying style is just there to provide an attack approach solution.

  2. May 8, 2011

    I wonder if they evolved to look like wasps to ward off potential predetors?

  3. May 9, 2011

    That would be my bet. As KT alludes to above, it’s hard to get a good look at a flying insect. And snatching a wasp out of the air is a good way to get a painful sting. So a bird is likely to just generally shun everything that is even vaguely yellow-with-black-stripes.

  4. Della3 permalink
    July 31, 2011

    Not only can birds (and many insects) see more colors than we can, but they can also see much more detail. (I recall a science article digitally enhancing photos of flowers to show the ultraviolet runways that these flowers display for incoming insects.) Birds have far better than 20/20 vision. That’s why I have to cover even the tiniest garden seeds with a light dusting of soil – so the birds won’t eat them. I’ve caught them in the act many times! And how else does a hawk spot a tiny mouse on the ground from so high above the earth? Therefore, I’m not so sure the birds are so easily fooled. Maybe only the young and inexperienced fall for such ruses. Perhaps the beetles are fooling some other predators (mantoids?), or perhaps they do, as Tim suggested, also have treacherous qualities of their own.

  5. Andrew Trueblood permalink
    March 31, 2012

    I noticed how u said they are only in the great lakes area. I noticed tree and we have those on are tree are tree justbodied when they started jmaking holes in are tree I think it almostkilled the tree i they are here in new mexico

  6. Andrew Trueblood permalink
    March 31, 2012

    Stupid phone srry for being iliterate

  7. April 1, 2012


    This particular species lives around the Great Lakes, but it has a number of similar-appearing relatives that live all over North America. They have slightly different patterns of yellow striping on the wing covers, but look practically the same at first glance.

  8. Nicole Gard permalink
    April 15, 2012

    I just found one of these in my back yard, on a green-flowerd milkweed plant, this afternoon. It looks pretty darn similar to your pics, except, as you stated, a “slightly different pattern of yellow striping on the wing covers.” We live in the Texas Hill Country. I hope they aren’t here to kill any of our trees… is that what they do? And if so, what is their tree of choice?

  9. April 16, 2012

    Nicole: It looks like the larvae of this particular genus of beetle mainly eat rotting wood, so I think they are most likely to be in trees that are already dead or dying. So while they might speed up the death of trees that are already in bad shape, they aren’t really the main cause of death. I don’t think that you have to worry about them particularly, although if you see an awful lot of them it might be a good idea to check whether any of your trees are in bad shape.

  10. devon permalink
    April 26, 2012

    Last night I was holding my daughter while she was asleep,and when I moved her head to my other shoulder. She started screaming, kicking and asked to go to the Hospital. She said a spider was on my shoulder and it bit her. So I looked at my shoulder and this same type of bug was on it. So they are not harmless!!!! I looked at her ear and it looked like a wasp sting. I put the bug in a tupperware because I did not know what it was. My daughter is fine! the redness and swelling went away after a few hours.

  11. Lee roberts permalink
    June 13, 2012

    Me and a friend found one of these whilst out walking in Shrewsbury Shropshire. Are they quite rare?

  12. June 13, 2012

    Lee: I don’t think they are particularly rare, but they are not so common as to see them in large numbers, either.

    In general, it is a pretty safe bet that any insect that you see on my pages here is at least moderately common. This is because I mainly photograph things that I or my family casually stumble across in our daily activities. To find things that are actually rare, we’d have to be putting some serious time and effort into seeking out, stalking, and capturing things that we otherwise wouldn’t be likely to see.

  13. August 5, 2012

    I’ve never seen them in my life that is one day when i was bringing the groceries home, i saw one by the grass, i used a card to move it away because i thought it would sting or bite me, then 3 days later i saw one in my room and it looks freaky so i put it outside. A week after i found another! so i put it on my hand but then i felt a small pinch which shocked me so i waved my hands and it flew away and i got an irritated red circle on my hand which eventually went away that day. I advise anyone not to put this near your skin.

  14. Barry Johnstone permalink
    August 18, 2012

    I found this beetle in Callander near Stirling on the river side

  15. August 20, 2012

    Barry: is that the Callander in Scotland (in which case your beetle is probably the same as the one Lee Roberts found a few comments up), or the one in Ontario (which would make it probably the same as the one I found)?

    (The Callander in Scotland is near a city named Stirling, so I guess it is that one).

  16. mell bee permalink
    September 20, 2012

    I saw little red spiders come off of this bugs anyone tell me how that is please

  17. September 21, 2012

    Mell Bee:

    There are a lot of kinds of mites that ride around on insects. Sometimes, they are just hitching a ride, and sometimes they are parasites sucking the insect’s body fluids. If you look at insects regularly with a magnifying glass, you’ll find various kinds of mites riding on them quite often.

  18. Sabrina cuevas permalink
    October 4, 2012

    They do sting!!!! my husband yelled a cow any jut but Dallas and upon inspection this is hat our 3 year old said stung him it was in a parking lot under a street lamp at nite but my 3 year old was attimate, he screamed for an hour and to watch the “bite” it looked more like stings, 2 times it stung him( I say stung because the bites were too far apart for any pinching or mouth action to cover the area.) needless to say he’s not going to get anyone else, and we are located in Gulfport, ms. No great lakes around here:/

  19. Josh Sylvester permalink
    March 12, 2013

    These are in our apartment in Dallas, TX. We have some wood in our living room that we keep in a basket for when it gets cold. Guess there was larva in this wood and now we find one probably every other day. Thank goodness the cat finds it every time before we do… one thing they’re good for!

  20. March 13, 2013


    After so many people commented about finding a similar beetle in Texas, and several said that it bit/stung them, I decided to look into it. I think you might actually have a type of blister beetle. I’ve added more information about blister beetles to the end of the posting. Upshot is, don’t handle them unnecessarily, don’t get their blood on your skin, and don’t let the cat eat them.

  21. June 27, 2013

    Pretty sure one of these was just flying around my bedroom! I sure thought it was a wasp, as I live in Arkansas and wasps are very common. But once it landed, I noticed the long antennae and that there was no narrowing through the middle. The flight pattern was also much more erratic than a wasp. Then the little guy started dive-bombing my lamp! I’ve never seen a wasp do that. So I’m sincerely hoping it’s a longhorn beetle hiding in my lamp, not a small wasp!

  22. Maranda permalink
    July 5, 2013

    These are living in our basement in Kentucky!

  23. marcy permalink
    July 24, 2013

    My daughter noticed one of these on her towel while swimming and knocked it off. She didnt feel a pinch or sting, however; she had a large circle(size of 50cent piece) on her leg. It was raised And very hot. They continued swimming and The chemicals in The pool irritated it even more. It is now about 7in in diameter raised and very Hot. Dr. Has her taking benadryl and hydrocortosine cream. She Stated it didnt hurt, it is Just Scary!!

  24. marcy permalink
    July 24, 2013

    We live in southern illinois

  25. Lindsay Nelson permalink
    July 26, 2013

    We just found this exact beetle in the Seattle-Tacoma area of Washington state. We have never been to The Great Lakes or Texas. Just thought I would share.

  26. Fred Taylor permalink
    April 15, 2014

    I just found hundreds of them around cut logs from a tree. I live in the northern NJ area and this is the 1st time I’ve ever seen them.

  27. Arlene Higdon permalink
    June 4, 2014

    I found this bad tempered guy in my living room in San Antonio Texas.
    I had never seen one like this, I did not think the color pattern was close enough to disguise it as a wasp but who knows bug IQ. He did not fly and he was so large I thought it was a plastic bug left by one of the kids( twisted humor here). I almost had my hand on him( we named him Yugo based on size) when I thought better and decided to give him a poke instead. He hissed at me, not a subtle warning, an outright threat. After capture for his photo session he was given many opportunities to fly but never took off. I have seen bugs similar to this here, mostly on Christmas tree farms but this this bad tempered guy was significantly different, and Christmastree bugs have distinct thorax, they fly readily, easily dodge a thrown ketchup bottle and don’t hiss. Most distinctive feature is the antennae. At least twice as long as body and the vicious hissing is an eye opener. You would never mistake this hostile yellow and black Beetle as a friend of humanity.

  28. Philip Ayers permalink
    June 5, 2014

    These look like a beetle observed here in NJ on buddlea(butterfly bush) it seems to damage the plant where there are large numbers. On one plant only a couple were observe on another it was covered. The foliage is wilted and dying.

  29. Vaylah Nikole permalink
    June 20, 2014

    I found something similar to this in Louisiana (where I live) and I was actually sting by it. Very painful. After three weeks, I still have swelling and a black sore. I would recommend not picking any up or startling them.

  30. Rita permalink
    July 23, 2014

    We found this beetle in our bathroom, in newfoundland canada, is it native to canada or was it taken over by boat?

  31. Rita permalink
    July 23, 2014


    this beetle is in newfoundland canada like i was saying the thimg is only way on or off newfounland is by boat or plane this is an island surounded by sea water. im guessing free trade brought this here yay for us notttt. this aint the only ugly beetle found here that dont belong here. nasty bugs

  32. July 24, 2014


    They may have hitch-hiked over by boat, but they also could have easily have come across on their own, probably over the strait between Newfoundland and Labrador. They are pretty strong fliers for beetles, and with a bit of wind behind them the 15 km distance would have been no trick at all. For that matter, the strait was a lot narrower a few thousand years back, when the sea levels were still low from the ice age, and it would have been even easier for them to get across then. Since their larvae are wood-borers, they could even have come across in dead trees that washed across the strait.

    Basically, since there are trees that made it to Newfoundland on their own, the beetles that eat the trees could easily have gotten there the same way the trees did.

  33. Alanna permalink
    August 23, 2014

    Today is August 23 2014 and I’m in The Kootenay area of British Columbia, Canada and I saw the exact same beetle.

  34. Rita Dawe permalink
    August 24, 2014

    Thank You Tim
    For your insight on the beetle found in my washroom. I have seen other beetles that are almost as big as some small birds when they fly. Scary really. But again thank you

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