Last week, I posted the above photograph of Enoclerus ichneumoneus (orange-banded checkered beetle) and mentioned its possibly mimetic appearance to velvet ants in the family Mutillidae (order Hymenoptera). By some stroke of serendipity, I encountered a species of Mutillidae the very next day in Missouri’s southeastern lowlands that seems to be a good candidate for one of, if not the, model species that E. ichneumoneus might have evolved to resemble. Several individuals were encountered as they zigzagged urgently on dry sand deposits along the Mississippi River (where I had hoped, unsuccessfully, to find another locality for our intergrade population of Cicindela scutellaris). Comparison of the individual in the photo with specimens in my collection (all identified by mutillid expert Kevin Williams, Utah State University) suggests this is Pseudomethoca simillima, and the photo is also a good match with other photographs of the species at BugGuide. One thing that bothers me with the idea of this being a model for E. ichneumoneus is that I have not seen P. methoca commonly in Missouri (I have only three specimens in my collection), while E. ichneumoneus is one of our most common clerids. There is another mutillid species in Missouri – Dasymutilla quadriquttata – that also seems to have potential as a model for E. ichneumoneus and that I have encountered much more commonly in the state. However, D. quadriguttata is somewhat larger than E. ichneumoneus. At any rate, other than the statement by Mawdsley (1994) that E. ichneumoneus seems to mimic mutillids, I can’t find that any more specific information has been recorded about the possible model(s) for that species.
As a caveat, I shall add that this mutillid was the… most… uncooperative… insect… that I have ever tried to photograph! They really never stop moving, so you have to track the moving insect through the lens and fire shots when you think you’ve got it centered and focused. Most of the time you don’t! Using the Canon 1-5X macro lens for this did not make things any easier. I tracked this female for quite a while and fired off a number of shots, only to get this one that I thought was fairly decent (and still just missed the focus on the near side of the pronotum).
Speaking of mutillids, I simply must photograph my specimen of Dasymutilla gloriosa (sometimes called the thistledown velvet ant) – you will not believe it!
Pseudomethoca simillima: Canon MP-E 65 mm 1-5X macro lens on Canon 50D, ISO 100, 1/250 sec, f/14, MT-24EX flash 1/8 power w/ Sto-Fen diffusers. Minimal cropping and post-processing.
Enoclerus ichneumoneus: Canon 100mm macro lens on Canon 50D, ISO 100, 1/250 sec, f/14, MT-24EX flash 1/4 power w/ Sto-Fen diffusers. Minimal cropping and post-processing.
Mawdsley, J. R. 1994. Mimicry in Cleridae (Coleoptera). The Coleopterists Bulletin 48(2):115-125.
Copyright © Ted C. MacRae