T.G.I.Flyday: Tachinomyia sp.
December 21, 2012 5 Comments
You would think that somebody with enough patience to photograph tiger beetles would be equally patient with “calyptrate” flies, but for me such is not the case. It’s not that I don’t find them interesting (although, really, what insect group can match the diversity, polytopism, ecological extremism and behavioral charisma of tiger beetles?), but their flighty, frenetic behavior and difficult taxonomy are just a bit too much for me. After all, why invest the time it would take to get a good photograph of something that, in the end will probably be unidentifiable.
Last April as I was hiking a woodland trail in Sam A. Baker State Park in southeastern Missouri’s Ozark Highlands, I saw this decent-sized fly bumbling across the trail. I knelt to look at it more closely, and though it tried to flee, it seemed too weak and uncoordinated to take flight. It was in beautiful condition—a perfect specimen, and I surmised that it represented a newly emerged adult that had not yet hardened sufficiently to withstand the rigors of flight. I was fascinated by its distinctive, orange tarsal pads and the white “beard” around its head, and the ability to coax the fly onto a leaf and hold the leave in whatever position I desired was all the enticement I needed to spend a little time with it. Out of the several shots that I took, these two are my favorites.
Of course, just being able to photograph the fly was only half the battle—there still remained the matter of its identification. It seemed “tachinidish” to me at the time, but a little digging revealed that there are species of Sarcophagidae look very similar to tachinids, the difference being the presence or absence of a visible postscutellum. My photos don’t show this character, and I quickly became overwhelmed when I tried scanning through BugGuide photos for these two families. Nevertheless, I’m a persistent sort, and after winnowing out the numerous unlikely choices I finally settled on not only family Tachinidae, but possibly Tachinomyia sp. (tribe Exoristini). I was tempted to go out on a limb and post the ID here unvetted, but I chickened out and and sent the photos to fly guy Norman Woodley at the Systematic Entomology Lab in Washington, DC. Norm supported my identification and wrote back:
I think it is probably Tachinomyia. It would be better to have a wing view as well as the hind end to be absolutely positive, but I’m reasonably sure that’s what it is. It’s a male. Some species are active in the spring, so that fits with your data as well.
Copyright © Ted C. MacRae 2012