Bee Fly

2009 August 22

I’ve seen these from time to time for years, but never really got a good look at one before. But, on August 15, this one obligingly landed on the concrete in front of our garage and quietly expired before my very eyes. This was a golden opportunity to get it onto my photographing stage, and take some pictures with the aid of my new robot slave[1].

It’s a Bee Fly, in the tribe Bombyliini, and if I had to be more specific I’d probably go with the genus Systoechus. They are sort of bee mimics, with the yellow body hair making them look like small bumblebees.



It might actually not be that apt to call them “bee flies” because they are more like tiny hummingbirds – they flit from flower to flower, hovering in front of them to drink, but hardly ever land or even hold still. I think you can see where this would make it hard to get a picture of one that is active. They even have an elongated proboscis, a lot like the beak of a hummingbird, so that they can drink the nectar without actually landing.



It turns out, though, that there is another reason for calling them bee flies other than their appearance: their larvae are parasitoids of solitary bees. What they do, see, is fly around flowers, drinking nectar to keep their strength up, while keeping an eye out for solitary ground-nesting bees coming around the flowers. When they spot a likely-looking bee, they apparently shadow her back to her nest! Then, as the unsuspecting bee continues stocking her nest with additional foodstuffs, the bee fly nips in while she isn’t looking and lays her own eggs in there. Finally, after the poor solitary bee lays her eggs and seals off the nest, the bee fly egg hatches, and the fly maggot goes in and eats the bee larva (and maybe some of the provisions that were provided for the bee larva).

Anyway, the bee flies are harmless, what with not having a stinger and all, but they do look enough like a bee to make most predators tread cautiously around them. And, they are fast and maneuverable enough that a little delay is all they need to avoid getting eaten.

[1] Back in July, I’d been griping to a friend (who is a very proficient photographer – Hi, Kevin!) about how I really needed some sort of off-camera flash [2] that wouldn’t cost an arm and a leg, and that could be triggered even though my camera doesn’t actually have any way to connect to a separate flash unit. He then told me that studio photographers sometimes use “studio slave flashes”: they are about the size of a compact-fluorescent light bulb, and screw into a standard light fixture. So, meet my robot slave – I got it from Adorama Camera for about $20:


The best part is that it has a sensor that detects when the on-camera flash fires, and so, with the speed of light being what it is, the slave flash goes off at the very moment when the camera is still taking the picture. Of course, that’s in theory. In practice, a lot of consumer-grade cameras (like mine) normally default to firing the on-camera flash twice, and take the picture on the second flash[3]. Unfortunately, when they do that the slave flash triggers the *first* time the on-camera flash goes off. It then has no juice left a fraction of a second later to fire the *second* time, and the slave flash might as well not even be there in that case. Luckily, though, my Canon A95 does have a full-manual mode where the flash only fires once, and so in manual mode, the robot slave works fine.

There is an easy way to tell if your camera flash is set correctly to run the slave flash: just take a picture of the slave flash unit and see what the picture looks like. If it is syncronizing correctly, it will look something like this:

Ach! Mine eyes! I am momentarily blinded!

Ach! Mine eyes! I am momentarily blinded!

There is one sort-of problem, though: this flash is actually way, way overpowered for what I am doing. It’s intended for lighting up a person in a photographer’s studio from about ten feet away, and I have it in a light fixture about two feet from my camera. If it is pointed directly at the subject, then even with the camera’s fastest exposure setting everything still comes out completely white. But, if I point it up and bounce the light off the (white) ceiling, it comes out just about right at 1/500th of a second exposure (and bouncing the light makes it diffuse enough that there are no harsh shadows).

I think the light quality using the flash is noticeably better, what with more uniform lighting. It also lets me hand-hold the camera sometimes rather than always using a rigid stand, because now the shutter speed is fast enough that the shaking of my hands doesn’t blur the picture. This is a big deal, because now I can take pictures from the side (or other angles) rather than being restricted to shooting straight dowh. Another big bonus of this is going to be when I photograph the little buggers that insist on scurrying or wiggling all the time. With the light fixtures I used to use, I generally couldn’t get much faster than a 1/30th second exposure, which meant the moving bugs were almost always blurry. The order-of-magnitude-faster shutter speed with the slave flash should take care of *that* problem!

And, since it screws into a light fixture that plugs into the wall, I don’t have to worry about batteries for it. The cycle time is pretty quick, it can easily keep up with my camera no matter how fast I take pictures. And, it makes a satisfying “PAF!” sound every time it fires, which for some reason I find very amusing.

[2] “So, what’s wrong with the on-camera flash?” I hear you cry. Well, the macro lens I use on the camera blocks the on-camera flash, and so it just wastes my battery without illuminating the subject. This problem is curable if I can just have a flash that can be put wherever I want, instead of being permanently embedded on the camera.

[3] There are a couple of reasons for a camera to flash multiple times for just one picture. The first flash firing can be used to check the light levels, and the camera can then automatically set the exposure to actually take the picture when it flashes again. Also, some red-eye reduction uses multiple flashes to contract the pupils of people’s eyes before the picture is taken. Both of these are actually pretty nice features, provided you aren’t trying to use a slave flash with your camera.

7 Responses
  1. August 25, 2009

    Another totally cool post. I love the frugality of your flash solution, too. Here within the Catican, we’re closing in on getting our goodies put away from the marriage and the moves. Once that’s done, we’ll reassemble the MGB and then I wanted to look into microscope photography. I’ll blog that exploration as it goes, but it’s still a little way off.

    Every time I see these insects these days I start wondering about their central nervous and digestive systems. Do flies have a brain, or are they just bundles of nerves glommed together near the head?

  2. August 25, 2009

    Well, here’s everything you ever wanted to know about fruit fly brains. It looks like they do in fact have non-trivial brains that have certain similarities even to our own brains, and they are actually popular subjects for neurological studies. For example, it looks like it is possible to make fruit flies get Alzheimer’s Disease, or something enough like it to be a worthwhile as a disease model.

  3. August 30, 2009

    Great post. Love the info. I have photographed one bee fly in flight, drinking from a flower, but never knew the full story.

  4. September 12, 2009

    thanks for the break down. I didn’t know that there were bee flies. I have a WW post of one on a daisy and one of my readers pointed out to me it was a fly and not a honey bee — but an important pollinator nonetheless.

  5. Sandra H permalink
    September 13, 2009

    DNLee, you’re not the only one… Some years ago the Christian Science Monitor ran a picture of a “bee”. I guess you’re a good mimic if you can fool predators but you’re a great mimic if you can fool the CSM.

  6. Raelynn permalink
    September 15, 2009

    Great info bee flies and hover flies, had no idea, here in Hermiston OR and being allergic to bees, I felt the need for more information thanks

  7. jazzbo permalink
    March 18, 2016

    Thank you. We have one in backyard. We were tripping. We got some good pics too and started searching. Found your pics. Great info.

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