Unknown flies

April 8, 2015 • 10:00 am

by Matthew Cobb

Outside my office I have a stupendous poster of the fly tree of life, showing the evolutionary relationships of the world’s flies, along with some lovely photographs. (You can download the poster from here.) This tree was produced to accompany a scientific article from 2011 describing the evolution of flies, which Jerry covered here.

When I have an idle moment, I like to inspect the tree for odd flies that I don’t know about and then find out about them. Which is how I came to be mooching around the web looking for the Ctenostylidae, which turn out to be a particularly weird group of 14 species about which very little is known. Here’s one (a male Sinolochmostylia sinica from China, taken from here):

Why are they weird? Well they have

  • No ocelli (most insects have three small eyes (‘ocelli’ in Italian) on the top of their heads, used for detecting movement and in flight)
  • No proboscis (this means they presumably don’t eat as adults)
  • Branched aristae (part of the antenna) in females (most flies have feather-like aristae)
  • They are viviparous (technically larviparous, as they lay larvae, like tsetse flies – NB that link might be NSFL)

They are probably parasitoids and may be nocturnal/crepuscular, but nothing is known of their ecology, or even their true distribution – they are found mainly in tropical regions, but also in Nepal, Korea and China. Their current taxonomic position, based on molecular analysis, is within the Tephritoidea – so they are related to the true fruit flies (Tephritidae) and the delightfully named flutter flies or Pallopteridae. You can learn about as much as we know about the Ctenostylidae by reading these two articles.

The fact that we have no idea about how these flies live should be no surprise. Most people in the world now live in cities, and we don’t know about the flies that live there, either. In 2012 the Natural History Museum of Los Angeles County launched a research initiative called NHM Biodiversity Science: City and Nature (NHM BioSCAN), with the aim of surveying the biodiversity of one of the world’s great cities.

In a sampling period lasting a mere three months, they discovered 30 new species of fly – not simply species that weren’t known in LA, California, or even the USA. These were species that had never been identified before, and there they were, buzzing about in an urban environment. Furthermore, those flies were from just one genus (a group of species, this one is Megaselia) called phorid flies. This suggests that other genera may hold similar richness.

Here’s a picture of the flies they found:


There’s a great post by Emily Hartop describing how she made the discovery, and the work she did with her boss, Brian Brown, and with the great English dipterist, Henry Disney.

There’s a nice couple of brief videos about BioSCAN. The first describes the project, the second shows how ordinary citizens are getting involved:

Look carefully around you, and you will be amazed by the diversity of life that can be seen, even if you live in a city. Next on my list from that Fly Tree of Life poster? Maybe the Neurochaetidae, also called upside-down flies. As of now, I know nothing about them, but they sound intriguing, and knowledge is only a few clicks away…


28 thoughts on “Unknown flies

  1. Occasionally I will notice a very small fly that doesn’t look like an everyday fruit fly. I cogitate briefly realizing that I have no clue what it really is or how it makes a living. Now I see that every time I spot one the chances are it’s not the same species as the last one I noticed. Maybe the odds are very much against it being the same species.
    I’d really like to get one of those traps for the back yard.

  2. Seeing how I hate fl**s, outside of their use to research departments, I can’t help. They are the set {big) annoying fl**s, (small) annoying fl**s} to me.

    [/waiting for the beetle and butterfly surveys]

    1. “The Fly”

      “The Lord in His wisdom made the fly,
      And then forgot to tell us why.”

      — Ogden Nash —

  3. Ah, the phorid flies. They have a slightly soft, squishy area in my heart. In my earlier history when I freshly deposited into grad school I would occasionally lurk in our departmental ‘Insectarium’ which housed a number of species of cockroaches that were kept in garbage bins. These were a source of fascination in their own right. But they were well infested with these little flies that zipped around with great agility. After some investigation I learned they were phorid flies, which was a fly family that I did not know about before. So whenever I see one — they are distinct with their large rear femurs and alert, darting movements — I am taken back to those heady days when my scientific life was just emerging & growing in unknown and unpredictable directions.

    1. Did you figure out what they found so fascinating about cockroaches? (I’m thinking maybe it’s some chemical attractant that could be bottled and place at the far end of the yard away from the picnic table and horseshoe pit).

  4. I didn’t see anything that would make the tsetse fly video NSFL, but it did give me sympathy pains in my nether regions, even though I’m a guy. I must say that was one hell of a birth! ouch!

  5. I wonder what that bulb-like structure on the back of the thorax is. If the adults don’t eat, I would imagine they don’t live very long. Just mate and die like Mayflies perhaps.

        1. Oh, then glad to be helpful! One never knows if one is speaking to a fly “innocent” or a fly expert, so I didn’t want to seem to be insulting your intelligence. 🙂

          Halteres, the modified hindwings of true flies, separate their order–the Diptera–from all other insects. And they’re very cool looking. 🙂

  6. “the fly tree of life”

    Otherwise known as the Tree o’ Flyfe.

    So basically the lesson is, if I see some strange bug in my kitchen and say “What the hell is that thing?”, there’s a good chance nobody knows.

      1. Well…I mean, I’m sure I’m not going to find any heavier-than-the-Higgs particles in my kitchen, but I could imagine trapping and photographing insects.


        1. But who is going to coordinate the effort of thousands of amateurs?

          Will they be assigned tasks? Who will process the results?

          1. Yeah…that’d be the hard part for the scientists. Along with the question of whether the payoff is worth the overhead.

            There’ve been distributed science projects before, such as the SETI@HOME one where you run a screensaver on your computer that processes radio telescope data looking for signs of intelligence.


  7. I have studied Ctenostylidae, and suspect that they are parasitoids of terrestrial planarians. If I can ever confirm it, it might even get published. 😉

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