Collecting weird lesser dung flies

I suppose I could have come up with a better title, but with all due respect to my friend and mentor Dr. Steve Marshall, the family Sphaeroceridae does not often lend itself to superlatives. You wouldn’t know this from reading his recent book, Flies: the natural history and diversity of Diptera, however, in which Steve gushes appreciatively about the hordes of dingy, drab brown flies that swarm over cow pies. He reserves special appreciation for the subfamily Homalomitrinae, a group he co-described with his colleague Jindrich Rohacek. These flies, unlike their relatively dull relatives, are bizarre looking creatures, with reduced wing venation, flattened heads, and thickened leg segments. The original specimen was a female collected with army ants in Brazil in 1930; others were found to be attracted to lights. The six known species are organized into three genera: 4 species in Homalomitra, 1 species in Sphaeromitra, and one in Podiomitra. There are fewer than 20 specimens known.


Look at the strange head, unusual “feet”, and incredibly reduced wing venation on this fly. Amazingly, we have collected at least three more already in our All Diptera Biodiversity Survey in Costa Rica, all from light traps. It will be interesting to see what other strange creatures are uncovered by our intensive survey of this tropical cloud forest. (photo by Inna Strazhnik).

6 comments on “Collecting weird lesser dung flies

  1. Wow, what a cool looking fly! I would be hard-pressed to have ID’d that as a sphaero if I came across it in residue.

  2. jeff Bjorck says:

    That is amazing! Especially the lack of venation.

  3. Is that setal comb on the profemora also unusual? Do you know what is its function?

    • phoridae says:

      EVERYTHING about this fly is unusual! I’ll have to muse on the possible function of such a sparse setal comb (grooming? traction?), but as Steve Marshall says in his new fly book, nobody has ever seen these flies alive, so it is all speculation.

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