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Bumble Bee-Mimicking Robber Flies

7-10-19 robber fly 0U1A0212Robber flies are a special group of predatory flies that possess stout, spiny legs, a dense moustache of bristles on the front of the head (mystax) that protects the robber fly’s head when it encounters struggling or stinging prey, and three simple eyes in a depression between two large compound eyes.

Certain robber flies resemble bumble bees. The evolutionary advantages of a harmless organism mimicking a harmful organism (Batesian mimicry) include deterring predators that are fearful of stinging bees. In addition, it also makes it more likely that a potential prey insect will come closer to the bee mimic, thinking the “bee” is looking for nectar or pollen, not a meaty meal.

A quick way to distinguish a robber fly from a bumble bee is to look at the antennae and wings. Flies usually have short, stubby antennae; bees, including bumble bees, have “elbowed” antennae (an obvious joint). Flies have two wings, while bumble bees (and most other insects) have four. The pointed, stout proboscis, bearded face, fleshy feet and long, tapering abdomen of robber flies are also identifying characteristics. (Photo: Laphria thoracica piercing a click beetle between the beetle’s hardened outer wings (elytra) in order to inject enzymes which will eventually allow the robber fly to drink its prey.)

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6 responses

  1. Bill On The Hill

    Fascinating Mary. Ingenious little devil. If I was a Robber Fly, I would consider this delicious subject matter, lol!
    Bill… :~)

    July 10, 2019 at 7:52 am

  2. Jean Harrison

    I got confused, Mary, by missing the hyphen in your title. I thought “Wow! That’s really interesting. A bumble bee eating meat”. Then as you described the differences, I thought “This looks more like a robber fly. Could Mary have gotten it wrong?”
    Silly me! Of course not. Maybe 4:30 is too early in the morning to read e-mails.
    It is still really interesting, even after I noticed the hyphen.

    July 10, 2019 at 9:14 am

  3. Alice Pratt

    That’s amazing! So the Robberfly is going to have a Beetle smoothie!

    July 10, 2019 at 11:59 am

  4. Josie Carothers

    Hello, Mary,

    How can I sign up a friend to your wonderful posts? Thank you for them. They enrich lives!

    Josie Carothers

    On Wed, Jul 10, 2019 at 7:20 AM Naturally Curious with Mary Holland wrote:

    > Mary Holland posted: “Robber flies are a special group of predatory flies > that possess stout, spiny legs, a dense moustache of bristles on the front > of the head (mystax) that protects the robber fly’s head when it encounters > struggling or stinging prey, and three simple eyes i” >

    July 11, 2019 at 12:23 pm

    • Hi Josie,
      Thank you for your kind comment. I’m afraid your friend has to sign him/herself up on his/her computer (you could do it if you had access to their computer). You just click on “sign me up!” and follow directions. I’m sorry you can’t do it remotely for someone else.

      July 11, 2019 at 12:26 pm

      • April

        I think it can be done on any computer, but you need access to their e-mail to send the confirmation.

        July 12, 2019 at 8:23 am

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