Photo details: Canon 100mm macro lens on Canon 50D (manual mode), ISO-100, 1/250 sec, f/22, MT-24EX flash w/ Sto-Fen diffusers.
When is a ctenuchid moth not a ctenuchid moth? When it’s a White-tipped Black Moth (Melanchroia chephise) in the family Geometridae!
I may be a beetle guy, but I also consider myself a competent general entomologist. What is a competent general entomologist? Someone who can identify any insect to order at first glance and a majority of them to family – regardless of one’s own taxa of expertise. Thus, when I encountered this mating pair of moths on the outside wall of my sister-in-law’s condominium in Seminole, Florida, I ”recognized” them as something in what I learned as the family Ctenuchidae (later subsumed within the Arctiidae, first as a subfamily and now as several disparate tribes). They had all the hallmarks of ctenuchids—black and red coloration, narrowish wings with light colored patches, and about the size of the wasps that they presumably mimic. Upon my return to St. Louis, I sat down to identify the moths—confident that their distinctive appearance would lead to the quick ID that never materialized after scanning through all of the ctenuchine pages at BugGuide. Frustrated, I resorted to posting the photo on the site’s ID Request, never questioning my ctenuchine placement. Precisely 4 minutes later, the moths were identified by John Maxwell as Melanchroia chephise and moved to their proper place—among the 50 other adult photographs of this species that can be found on the site! I might as well have failed to identify a monarch butterfly!
Melanchroia chephise is apparently common in the American tropics, reaching its northern distributional limit along the coastal plains of Florida and Texas but straying further north in certain years. Larvae feed on several plants in the family Euphorbiaceae, primarily Breynia and Phyllanthus species. The adult coloration strikes me as obviously aposematic (warning coloration), but I could find no specific references to this. However, considering that euphorbiaceous plants are famous for their diverse arsenal of latex and irritant toxins (e.g., diterpene esters, alkaloids, glycosides, ricin-type protein toxins, etc.), it seems reasonable to presume that Melanchroia larvae have evolved mechanisms for sequestering one or more of these compounds. NABA South Texas states that adults of this species are probably mimics of the Red-bordered Pixie (Melanis pixe), an aposematic metalmark butterfly also of Neotropical distribution that reaches south Texas (but not Florida). Personally, I don’t really see the resemblance (but then, nor am I an avian predator). I suppose it’s possible that a species such as this can employ different defense strategies in different parts of its range, relying on Batesian mimicry in areas where suitable models occur and aposematism in areas where they don’t, but I have to admit that I’m now straying well outside the coleopteran-centric bounds of my expertise.
Copyright © Ted C. MacRae 2009
Ted C. MacRae
jtrager
My first thought was “looks like Ctenucha virginica”…fooled me too. I agree that it doesn’t look like M. pixe either, at least not more than very superficially; I’ll join you on the “safe to presume sequestration” bandwagon.
That’s exactly what first came to my mind as well. Although I knew it was not that species, the similarity it showed to that species convinced me it was something related.
“I might as well have failed to identify a monarch butterfly!” I laughed uproariously at that. Ever seen a viceroy? Well, they don’t really look like monarchs as far as I’m concerned, but your statement reminded me of Alex’s post on the mimic issue. Thanks for the chuckle.
The photo is gorgeous, as are the subjects! And I like images that show the more intimate side of nature (i.e. critters gettin’ to know each other in the biblical sense). Being a prude isn’t my thing.
Cool learning experience. I know a lot less than you about insects, so I pretty much feel certain I would have made a similar mistake trying to ID them. (At least now I can always point and say, “Well, he did it too, and he’s a lot smarter than me!”)
BTW, the ’subscribe to comments’ function seems to be broken. Each time I leave a comment and check the box, I get an e-mail saying I have to click a link to confirm that I want to receive notices for future comments on that post. It happens for every post I comment on. But when I click the links, I’m asked to login with a wordpress.com ID and password so I can confirm. Strange… (Or is it just me? That would not surprise me in the least!)
I don’t know what to tell you, but I quoted your remarks in a question I posted on the WordPress forums to see if anybody knew what was going on. No answers yet, but another commenter has responded to that saying he’s having the same problem. I’ll let you know as soon as I hear something.
I’m with you – photos that reveal aspects of behavior and biology are much more interesting. If you like bug love, you’ll enjoy the photos in my post, Oklahoma is for lovers.
Great story, Ted. The detail in the photo is superb. I hope I can remember the “moral” of the story when I next get fixated on an ID.
Thanks, Wilma. I’ve learnt this lesson many times yet still keep having to re-learn it!
Those who know better sometimes even confuse Monarchs and Viceroys. The Idalia Soc. occasionally has specimens donated by collectors and offered for a donation to benefit the society. I found a diminutive Monarch that had been passed off as an unwanted Viceroy and snatched it up. We all make mistakes but it is admirable when we are willing to admit it.
Phil
Hi Phil – well, I don’t feel too bad about it, since I am, afterall, a coleopterist. I would have a hard time ‘fessing up if I was a lepidopterist and mis-ID’d a monarch as a viceroy!
Ted, Your bug can be common along the Texas coastal plains primarily from September through December. (See link.) In 2007, strays were recorded from Arizona, Oklahoma, Arkansas, Kansas and even southern Illinois!
Mike Quinn, Austin
Hi Mike – southern Illinois, huh? Makes me think it may show up someday in southern Missouri. I’ll have to keep an eye out.