As a student of woodboring beetles for more than a quarter-century now, I’ve had occasion to encounter a goodly number of checkered beetles (family Cleridae) – both in the field and as a result of rearing them from dead wood. Checkered beetles are not as commonly encountered as other woodboring beetle families such as Buprestidae and Cerambycidae, and they also generally lack the size, diversity, and popularity with coleopterists that those aforementioned beetle families enjoy. However, despite these shortcomings as a group, checkered beetles are among the most brightly colored and boldly patterned of beetles. Unlike the beetles with which they often found, checkered beetles are not actually themselves woodboring beetles, but rather predators of such (particularly bark beetles in the weevil subfamily Scolytinae).
This particular species, Enoclerus ichneumoneus, is one of the more conspicuous members of the family in eastern North America. Although the genus to which it belongs is the largest of the family (32 species in North America north of Mexico), the wide orange band across the middle of the elytra and elongate scutellum make this species distinctive and unlikely to be confused with any other. I found this individual along the Ozark Trail in southern Missouri on a recently fallen mockernut hickory (Carya alba) – a number of other adult buprestid and cerambycid species were also found on this tree, all of which were mating, searching for mates, or laying eggs within the cracks and fissures on this new-found resource. In the past I have encountered large numbers of adults of this species on dead willow (Salix caroliniana) from which I later reared an even larger number of a small willow-associated buprestid, Anthaxia viridicornis. Whether the buprestid larvae served as prey for E. ichneumoneus is difficult to say, but no other potential prey beetle species were reared from the wood.
The bright, distinctive colors exhibited by many checkered beetles might seem to suggest aposematic, or warning, coloration to discourage predation; however, the question of checkered beetle palatability to predators has not been adequately studied (Mawdsley 1994). The colors and patterns of many species, especially in the genus Enoclerus, seem to mimic species of velvet ants (family Mutillidae) and true ants, but other beetles (e.g. species of Chrysomelidae and Tenebrionidae) and even flies have also been suggested as models. Still other checkered beetle species seem to be more cryptically than mimetically marked, and there are several tribes whose members seem to be chiefly nocturnal and are thus mostly somber-colored.
Of the 37 genera occurring in North America north of Mexico, I have in my collection representatives of more than 100 species in 23 of those genera. The majority of that material has been reared from dead wood collected for rearing Buprestidae and Cerambycidae – much of it coming from Texas and Arizona as well as here in Missouri.
Photo Details: Canon 100mm macro lens on Canon 50D, ISO 100, 1/250 sec, f/14, MT-24EX flash 1/4 power w/ Sto-Fen diffusers, photo lightly cropped.
REFERENCE:
Mawdsley, J. R. 1994. Mimicry in Cleridae (Coleoptera). The Coleopterists Bulletin 48(2):115-125.
Copyright © Ted C. MacRae
Beetles In The Bush 
“…reared from dead wood…”
Is this as simple as dragging a log home and placing it in an aquarium or a screened enclosure? I am wondering, as a northerner, if this would work if I collect the wood in autumn and keep it at room temperature through the winter. Will the lack of freezing affect the development of any larva? It sounds like it could be a useful resource for those of us who are snow-bound for 5 months of the year.
And does this mean I have to take a chain saw with me on field trips? 😉
This is a question I have too…
*waiting impatiently for Ted’s words of wisdom on the subject*
You’re wait is over! Actually, I’ve been wanting to do a blog post on this very subject, but there are just so many details to consider, and I’ve not been sure of the overall interest on something so specialized.
Yes, the rearing part really is that simple. It’s the deciding which pieces of dead wood to drag home that is the hard part! Retrieving wood from the field, putting it up in containers, checking for emergence periodically, and wetting down the wood once or twice during the season is a lot of work – you want to have a pretty good idea that the wood you’re dragging home actually has larvae in it. This sounds easier than it really is – most buprestid and cerambycid larvae utilize freshly dead wood and are done after the wood is a year old. Dead wood, however, hangs around in the field for a long time – especially in drier climates like the desert southwest. It takes some practice learning what host plants are likely to harbor certain species, being able to identify the plant species based only on characteristics of dead wood, and knowing at a glance if the wood is of the right age to harbor larvae. Occurrence of larvae can be confirmed by slicing into the wood with a knife (smaller species) or chopping into it with a hatchet (larger species); however, this also is a lot of work and time, and you don’t want to be doing this any more than you need to.
And yes, I keep a chainsaw in the truck during my collecting trips 🙂
“…fresh dead wood…”
So telephone poles don’t qualify? 😉
😀
That’s a much more interesting looking beetle than the only clerid I remember working with – Enoclerus lecontei – back in the days when I was a committed coleopteraphile. But that was in another country …
Aposematic colourations does seem a reasonable hypothesis, especially given the contrast with other clerids such as E. lecontei – which I remember as being camouflage-coloured (implying visual predation). But the only papers I can remember reading about clerid behaviours were their responses to semiochemicals and their predilection for bark beetles.
I remember Enoclerus lecontei from my first forays into the Sierra Nevada after moving to California from Missouri. Yes, they were quite cryptically colored.
I look at the red abdomen poking out from under the elytra (I suspect this was a female probing for oviposition sites), and it just screams “I taste really bad!”
Fuzzy! It’s a striking beetle. I always think predators are the best looking critters. But it’s interesting that we don’t know about the colors. Still so much to learn…
And I laughed at Adrian’s chain saw question. The first image in my head wasn’t of him cutting apart dead trees but instead cutting down live trees before saying “Well, it’s a dead tree now.”
Actually, you’re idea is not so far-fetched – I have done lots of targeted rearing by cutting wood in late winter or early spring and leaving it in situ for a season to allow it to get infested before retrieving it the following year and putting it up in containers. I have reared lots of species this way that I would not have otherwise encountered.
The best wood for rearing seems to be dead branches shedding naturally from old, declining trees.
SHINY! Seriously it’s a really pretty critter. I think the first beetle I photographed was an Enoclerus…I found it in my house (the terrible photo is on my blog somewheres). I agree with you and macromite about the aposematism…it’s too stand-outish, and all that fuzz is certainly suggestive of a hymenopteran.
The thing that’s got me questioning the mutilled-mimicry idea is the fact that mutillids are largely encountered on the ground, especially in dry, sandy areas, while these beetles are encountered primarily on trees and branches (dead or live). I guess if the bird learns the lesson in a sand prairie, the lesson is still good when it flies into the forest, but it still seems a little iffy. Aposematic warning of chemical defense would be a simpler explanation – why won’t somebody sit down and feed some beetles to a few birds and lizards and figure this out once and for all? 🙂
If you’re ever interested in woodborers from the NE let me know. We have a large rearing facility where we do just that—fell infested (with an invasive woodboring pest) and dead pine trees to bring back to our lab to rear out the insects.
We cut billet sections, wax the ends, and put them in poly drums with screening.
Sure I’m interested. Do you need somebody to do identifications? I’m pretty snap with Buprestidae and Cerambycidae.
I have no doubt that it’s a mimic, especially now that I see the photos in your new post. Nice pics!
Thank you, John. I have no doubt that it is involved in some sort of mimetic relationship, but whether it is Batesian or Mullerian is another question. One tenet of the former is that the mimic (which is harmless) must be relatively rare compared to the model, and E. ichneumoneus is anything but a rare species. This suggests to me that the beetle might actually be protected as well (perhaps chemically), and its resemblance to mutillids is more an example of Mullerian mimicry where unrelated protected species evolve to resemble each other’s aposematic coloration. I wouldn’t be surprised to see lizards throwing up in feeding studies with this species.
Very interesting! I did wonder about the possibility of a mutual mimetic relationship or one where the mimic and model switched roles, although it makes sense that both species would have to be protected for that to occur.