Look at this fly!

Once again Dr. Cobb has made a good find on Twitter; what would I do without his careful scrutiny of social media?  LOOK AT THIS FLY!

Here’s the one at lower right, enlarged. I call it the “reindeer fly”:

It’s a fly in the order Diptera (of course) and in the family Mydidae, which is a small family (ca 470 species) sometimes called “Mydas flies“. It includes the world’s largest fly, Gauromydas heros, which can reach nearly 3 inches long (7 centimeters). It’s pictured below, but a year and a half ago National Geographic reported that there are two new species in the same genus that might, in the wild, have individuals larger than G. heros (paper here). In the meantime, this is one of the record flies:

Bug Guide shows a few of the cool Mydas fly species, with some having those weird club-like antennae and several being wasp or bee mimics:

Pseudonomoneura hirta – Male

Mydas clavatus

Delhi Sands flower-loving fly – Rhaphiomidas terminatus 


  1. Posted June 19, 2017 at 10:49 am | Permalink

    I am pretty sure Matthew should be marking something or writing his book 😉

    Vey nice, as always…

    Do you suppose the males & females have different antennae? Females to sniff out the males or vice versa?

  2. Posted June 19, 2017 at 11:17 am | Permalink

    Why does the fly have antennae like that? Is it a mating display? Or is it functional – in the way antennae usually are and if so, why that shape?

    • Posted June 19, 2017 at 11:42 am | Permalink

      No idea, but I speculate they grabble with them. This is more likely if just the males have them.

  3. Posted June 19, 2017 at 11:22 am | Permalink

    Now I can spend the summer looking for Mydas clavatus, along with my other bugs. Probably the only Mydas here in Vermont, but no recorded sighting yet. Thank you! Love finding new bugs.

  4. rickflick
    Posted June 19, 2017 at 11:27 am | Permalink

    Amazing diversity.

  5. busterggi
    Posted June 19, 2017 at 11:36 am | Permalink

    We’re gonna need a bigger swatter.

    • darrelle
      Posted June 19, 2017 at 2:38 pm | Permalink

      That might just make them mad. That might be a bad idea.

    • infiniteimprobabilit
      Posted June 19, 2017 at 3:42 pm | Permalink

      Sadly, that was my reaction too…


  6. Posted June 19, 2017 at 11:43 am | Permalink

    Mydas flies are pretty awesome. I see the big Mydas clavatus buzzing around at times, but have never been able to take a picture. They are a mimic of a large spider wasp.

  7. Posted June 19, 2017 at 12:12 pm | Permalink

    There’s a mutation of the antennae in Tribolium beetles called ‘reindeer’, but it’s not nearly as close a resemblance as this fly. Scroll down to see it here.

  8. Posted June 19, 2017 at 12:20 pm | Permalink

    G heros.. a hearty meal for a predator, a freek out for a wife and a major update on fly diversity. Very interesting antennas in colour, shape and size.

  9. Heather Hastie
    Posted June 19, 2017 at 12:40 pm | Permalink

    Beautiful as it is, I’m not sure I’d want one crawling around on the palm of my hand!

  10. Mark R.
    Posted June 19, 2017 at 1:09 pm | Permalink

    That is one huge fly…the maggot must also be huge. yikes. These are all really amazing.

  11. darrelle
    Posted June 19, 2017 at 2:49 pm | Permalink

    Before finding WEIT I had no idea flies were so diverse. Fascinating. The “reindeer” fly looks similar to robber flies.

    That G. heros fly is stupendous. Up to 3″? And I thought horse flies were big. I hope this one doesn’t bite for blood like a horse fly. Might need stitches after something like that.

  12. Posted June 20, 2017 at 6:55 pm | Permalink

    Very cool. Now we just need a Santa fly.

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