A Dagger Fly, Victorious


A dagger fly (Diptera: Empididae), eating a fly it caught.
Shawnee National Forest, Illinois

Among the insects, one lineage in particular excels in the air: Diptera, the flies. These animals have evolved a gyroscopic control system that’s faster and more efficient than the standard insect sensory system, and as a consequence the flies are the most agile fliers on our planet. Their numbers include some spectacularly maneuverable aerial predators such as the fly pictured here, hanging from a leaf to consume its prey.

Photographing these subjects posed two problems. First, flies are highly visual creatures, easily spooked by a camera flash, so I often got only one attempt at any individual fly. I’d take a shot, then have to hunt down another fly, and then another one, and so on.

Second, the resting position of the flies meant that the fly was often shaded by the overhanging leaf. With the flash units mounted on the camera, positioned above the subject, the leaf received the full glare of the flash while the fly sat underexposed on the bottom. Like so:


This lighting? Not great- the leaf is blown out.

To get the photo at the top of this post, I hand-held a flash head behind the subject (a delicate maneuver so as not to spook the sensitive animals) so that the flash would diffuse through the leaf rather than bounce full back at the camera.


photo details: Canon EOS 7D camera
Canon MP-E 65mm 1-5x macro lens
ISO 100, f/13, 1/250sec


  1. #1 dmaas
    June 19, 2010

    Fantastic! The results were defintely worth the efforts!

  2. #2 JasonC.
    June 19, 2010

    Very cool! The eyes look like they were painted or something on the first one. How many shots did you have to take to get these three?

  3. #3 Alex Wild
    June 19, 2010

    Looking back at my files, it seems I took about 50 shots. In my eye, the top one is the winner.

  4. #4 Adrian T.
    June 19, 2010

    A great shot.

    I have started experimenting with moving a flash behind the subject as well – its great for accentuating hairs or bristles. Is your Canon flash wireless? It certainly eases the problem of dangling cords brushing against the plant and startling the subject.

  5. #5 Troy Bartlett
    June 19, 2010

    I was wondering what these flies were. I have a gazillion in my backyard. I photographed one a few weeks ago, but hadn’t gotten around to researching it yet. You saved me the effort!

  6. #6 Janet
    June 19, 2010

    Hi Alex,

    Is this one also the same species that offer gifts to the females wrapped in silk? Do you know if they get the silk from spider webs? I wasn’t able to find that bit of info. Great shots!

  7. #7 janet
    June 19, 2010

    After a bit of digging, I found it. “Male hilarine flies (Diptera: Empididae: Empidinae) present prospective mates with silk-wrapped gifts. The silk is produced by specialised cells located in the foreleg basitarsus of the fly.” Cool. I didn’t know some Diptera produced silk.

  8. #8 biobabbler
    June 20, 2010

    1. SUPER interesting post. I’ve never heard of these guys.
    2. Amazing shots.
    3. Is it me, or does the dagger fly in the second picture look JUST like a TEENY tiny Darth Vader? Complete with black helmet and black cape.

    =) Now I have to look those puppies up–I’m very intrigued by the thread…

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