Desmocerus palliatus – elderberry borer

Desmocerus palliatus (elderberry borer), Squaw Creek Natl. Wildlife Refuge, Missouri.

Last June I made two trips to the Loess Hills in northwestern Missouri to survey additional sites for Cylindera celeripes (swift tiger beetle), which my colleague Chris Brown and I had discovered in some of the area’s few remaining loess hilltop prairie remnants the previous year. One of these potential new sites was  Squaw Creek National Wildlife Refuge, where a few tiny slivers of hilltop prairie can still be found on the fingers of loess bluffs that border the refuge’s several thousand acres of restored wetlands that famously host large concentrations of snow geese and bald eagles during the fall and spring migrations.  On the first visit, I had arranged to meet with Corey Kudrna, Refuge Operations Specialist, who was kind enough to take several hours out of his day to personally guide me to each of the site’s loess hilltop prairie remnants. 

As we crossed the highway right-of-way at the base of the bluffs on our way to the one of the remnants, we passed through a large patch of common elderberry, Sambucus nigra ssp. canadensis.  Anytime I see patches of this plant, especially in June, I immediately think of Desmocerus palliatus (elderberry borer) – a spectacularly colored longhorned beetle (family Cerambycidae) that breeds exclusively in the living stems and roots of this plant.  It is not a particularly rare species, but for some reason I have not had much success in finding this species.  In my close to three decades of collecting beetles, I had encountered perhaps a half dozen individuals – never more than two at the same time.  Still, when I get the chance to look at elderberry I look for this beetle, and when I did so this time I was delighted to see one within a few moments of entering the patch.  I was ecstatic when I saw another one almost immediately after the first, and I was stunned when I realized that they were all around me!  Good fortune continued on my subsequent visit two weeks later, when I was able to spend a little more time trying to get a good field photograph.  Wind was a problem, the beetles were easily alarmed, and their tendency to rest in the upper reaches of the plant made it difficult to brace myself and the camera while shooting, making this a rather difficult subject to get a good photograph of.  The photo shown here is literally the last of around two dozen that I took and is the only one that I really like.

Many cerambycid beetles are mimics of other more noxious species, mostly ants and wasps.  However, elderberry borers appear to be the exception in that they are themselves noxious.  The cobalt blue and bright orange coloration of the adults screams aposematic (warning) coloration, and it is reasonable to assume that they accumulate in their bodies for defensive purposes the cyanogenic glucosides produced by elderberry plants (Huxel 2000).  Even their movements are those of a chemically protected model – lumbering and clumsy, without the alert evasiveness usually seen with other flower longhorn species.  Presumably this species participates in a Müllerian mimicry complex involving netwinged beetles (family Lycidae, particularly species in the genus Calopteron) and perhaps Pyromorpha dimidiata (orange-patched smoky moth, family Zygaenidae) as well, and it may serve as a Batesian model for the equally colorful but completely innocuous Lycomorpha pholus (black-and-yellow lichen moth, family Arctiidae).

Photo Details: Canon 50D w/ 100mm macro lens (ISO 100, 1/250 sec, f/10), Canon MT-24EX flash w/ Sto-Fen diffusers.


Huxel, G. R.  2000.  The effect of the Argentine ant on the threatened valley elderberry longhorn beetle.  Biological Invasions 2:81–85.

Copyright © Ted C. MacRae 2010

31 thoughts on “Desmocerus palliatus – elderberry borer

  1. Wonderful. I can still remember my finding a beautiful orange Desmocerus in southern Oregon on Sambucus when I was in high school. (Come to think of it, that was over 50 years ago). Now I’m depressed.

  2. We actually have quite a number of these around, they’ve gotten into our house and been photographed at least twice so far. The thing is, I haven’t been able to find the elderberry bushes that they live in. They can’t be far from the house, but they must be well-hidden in the other shrubbery. I have to keep looking, though – I love elderberry jelly.

    • Elderberry is sun-loving, and the white flower heads are unmistakeable from afar – it’s got to be somewhere nearby.

      I wonder if these beetles might be a little more common further north of my usual haunts in southern Missouri.

      • Checking into this more, I realize that I *do* know where the elderberries are. It’s just that they aren’t the ones I was expecting. It turns out that in addition to the ones with black or blue-black berries (which were the ones I used to collect for my mother in southern Michigan), there is also a cold-climate species complex with red berries (which is what it turns out we have growing off north of the house).

        • Ah, Sambucus racemosa – red elderberry. I don’t know that the beetle has ever been formally documented as breeding in that host species, so if you could find evidence of larval feeding in the stems…

  3. Very cool. Elders are in flower at the moment down in here New Zealand, we’ve been busily turning a few of the flowers heads from trees in our section into elderflower cordial.

    But it appears we didn’t import any elder bugs when we introduced the trees to NZ, they actually seem strangely lifeless and aren’t even visited by pollinators.

  4. It’s a very attractive beetle (and a very good photo to boot). As I was reading through, I began wondering precisely what it was mimicking. Obviously you don’t have to mimic when you really are as bad tasting as you advertise.

    And I giggled at your photographic difficulties. I can relate. Some of the awkward positions I’ve contorted and stretched myself into just for that one good shot… (Usually resulting in no good shot, I might add.)

    • Sometimes I feel like I go on too much about how hard it is to take photos of this or that. However, when I take two dozen photographs of something and just get one shot turn out (barely), I need to vent!

  5. Ah, Desmocerus…the beetles whose fathers all smelt of elderberries!

    I’ve only seen one Desmocerus in the wild. Unfortunately, it was D. californicus dimorphus. I took a few pictures and then forced myself to walk away.

  6. We have lots of elderberries at Bluff Spring Fen. I’ve only ever managed to see one individual of this species. Your photo inspires me to redouble my efforts next year.

    • I wish I knew the key to finding this species. Elderberry is extraordinarily common along roadways all throughout Missouri. I can’t tell you how many times I’ve stopped during June and looked for this species, nearly always unsuccessfully. I never even really expect to see it anymore, even though I still stop and look. Finding so many in this one patch – unremarkable in any other respect – was completely unexpected.

      If you fail to find it at Bluff Spring, I know a good patch in northwest Missouri…

  7. Pingback: An Inordinate Fondness #11 – Kindergarten Kunstkammer « The Bug Whisperer

  8. I live in St.John’s NL Canada & I have been noticing these beetles for the last three years. Every year at this time my otherwise healthy Golden Alder leaves seem to be drooping and eventually the whole tree seems to be dying. On inspection I discovered these beetles all over the leaves. I haven’t seen them on anything else in my garden.I’m actually thinking of getting rid of the Golden Alders altogether.

    • Hi Paula — I’m not sure what beetle (or other insect) is on your alders, but since this one breeds exclusively in elderberry (genus Sambucus rather than Alnus) I don’t think this is it. The fact that you found beetles congregating on the plant may not even be related to the drooping symptoms you describe. There aren’t any beetles that look similar to this one the feed on alder as far as I know, so for now the cause of your alder problems will have to remain undiagnosed – sorry!

  9. Hi, I live in Minden, Ontario. I saw this beautiful beetle arrive about 4 o’clock this afternoon. Stunning colours. Got a great digital picture of it all shiny blue and orange in the sunshine. It was resting on a clump of echinacea that hasn’t blossomed yet. Would love to provide the picture if you give me an email address.


Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s