At least two big “fly announcements” are coming soon. Meanwhile, I am posting this photo of an antler fly (a type of fruit fly from New Guinea) for your entertainment.
I call these “miracles” not in the religious sense, but in the unlikelihood that I would notice them in a “normal” sample with all the macro-garbage obscuring them.
The first is a male, perhaps of the genus Metopina, with the thick costal vein almost as long as the wing.
Next is a bizarre female termitoxeniine that has not yet shed its wings.
A relatively “normal” wingless female Chonocephalus.
Finally, a flattened male of a new phorine genus with a short costa.
And I still have many more vials to look through! Life is good.
All photos were made by Inna-Marie Strazhnik, who is a superb artist.
I am sorting through a bunch of Malaise trap samples from Thailand from which all the insects larger than about 2 mm have been removed. The absence of larger insects makes all the tiny ones stand out, so these samples, the “microfraction” are golden. They are full of treasures: usually overlooked tiny things like Chonocephalus, termitoxeniines, and weird Metopina group males. I’ll publish more photos soon, but here are a couple I photographed previously.
Note the shieldlike crest on the back of the head in the second photo. Totally bizarre.
Microfractions represent yet another largely unexplored frontier of tropical phorid diversity. After nearly 30 years of doing this, I can still be amazed and awed by “my” flies.
Here are some options; look at the abdomen:
Significant “speckling” here, where each bristle reflects the flash. Ugly.
The natural light is so much better. Look at the details visible (click on the image to see a larger version). Too bad it is impractical.
I could go on and on about this, but even I’m getting bored. Besides, someone else has a great website about macrophotograpy lighting. Look at this site for amazing images and how they were made: http://orionmystery.blogspot.com/ . I don’t have to reinvent the wheel here.
Back to flies next time.
Okay, based on parts 1 and 2 of this series, you want to use high apertures (lens f-stop settings) to get lots in focus, but you need to use intermediate apertures to avoid diffraction blurriness. Either you have to focus stack (often impractical in the field) or accept a compromise f-stop like f11. So how does f11 work for you?
In all but the brightest light, f11 (or f8) will require long exposure times, giving ample opportunity for you or the fly to move, blurring the exposure. We’re back to either needing a motionless fly (unlikely) or, this time, more light.
Wait, can’t you just dial up the ISO (sensor sensitivity) on your new digital camera so you can use a faster shutter speed? Yes, but you increase the digital graininess (“noise”) in the photo, such that resolution at high magnifications is destroyed.
Here are a series of closeups of bristles on a tachinid fly showing this effect:
This series of shots tells me that, for my camera, ISO 200 is about the same as 100. For ISO 400-800 I get some degradation, but it is still pretty good. Above ISO 800, thing get pretty mushy. You need to check this in your camera, too.
The result is that changing ISO only helps me a little. If I want the highest quality images, I need more light. How to get this light is my next topic.
Firstly, such spiny flies are almost invariably found in species associated with ants, especially army ants. As evidence for this, here are 3 flies from the New World tropics found with Labidus army ants: Acontistoptera, in which the long setae (bristles) are found almost only on the wing rudiments, Adelopteromyia, which are spiny on the wing and on the body (especially the head), and Xanionotum, which has multiple rows transversely across the abdomen.
The large setae could be used to fend off attacking ants, like a porcupine, or for sensory purposes in the darkness of underground ant colonies. Or both. One thing to keep in mind is that the flies probably can move the setae, erecting them or laying them down. They are much more flexible, mobile, and speedy than you might think, as they literally runs circles around the host ants.
As I showed in the last post, at high magnifications you can only have a small amount of your subject in the sharpest focus because diffraction limits useable depth of field. Now you have two choices: stacking or settling for some different compromise.
The image above is a blended stack of 25 images, all of which only have a bit of the fly in focus. I used a program called Zerene Stacker to do this, but there are other options. You can make some phenomenal images this way (just look at the forums at www.photomacrography.net), especially using tens to hundreds of source images, but there is a catch – your subjects have to be motionless, preferably dead. Some field photographers can get short stacks of a few images of resting flies, but generally flies are 2. active. For me, it is better to pick a compromise lens setting like f 8-11, as discussed last time, to get good shots of lively, moving flies. If you want more information on stacking, though, see the free resources at www.macrostop.com.
Next: how do you get enough light to use f 11?
Flies are fantastic subjects for photography, but they present many challenges because they are
3. often metallic and bristly.
All of these are factors that cause problems that I’ll discuss in the next few postings.
[The reason I’m writing about this is that there is so little good macrophotography information about insects like flies. I assume interested readers know the basics of 35 mm digital photography. If this subject doesn’t grab you, go back and re-read the last post by Lisa Gonzalez, which was a real crowd-pleaser]
When you photograph small things at high magnification, your depth of field is frighteningly shallow. Take a shot at f 1.4 and you’ll get maybe one tarsomere and a wingtip in focus. The rest will be a blur. Therefore, you need to close down to f 22 or f 32 to get everything in focus- correct? Unfortunately, when you do this, you start to distort the image through diffraction. It’s not really a problem when photographing big things (like landscapes), but flies are 1. small.
Above is a good-sized tachinid fly. I photographed it with my camera (Nikon D-7000) on a tripod, using a 125 mm macro lens set at f 22. At this magnification it looks pretty sharp, but look closer (below). You’ll softness from diffraction that no fly obsessed photographer (and I hope you are one) would tolerate. And since most flies are smaller than this tachinid, what we see in this magnified view is ALL we’ll get.
At the next setting, f 16, sharpness is definitely better. Scroll down to see other settings.
The problem, of course, is that by f 5.6 the legs are all out of focus. You have to pick a compromise (f 11 works for me) or do something else, photostacking, which only works well with stationary objects (and remember, flies are 2. active). More compromises are ahead.
To get the best results, you first need to know what your camera can do. Everyone needs to test their camera and lenses this way to see what is possible. Then you can move on too what is practical.
Next- how do you get to use that f 11 setting?
I suppose most people have anxiety dreams, in which things are going horribly wrong because, in their dreams, they are late, lost, without something vital, or otherwise unable to figure out what’s going on. Being an entomological geek, and obsessed with field work, my anxiety dreams are often centered around being in a great tropical place, surrounded by social insects like ants and bees, but not having collecting equipment, having to leave, rain starting, and so on. I wake up frustrated, hoping that next time I’m in the tropics none of these things happened to me.
A couple of days ago, we pulled off the road in an area known to the locals as “Bambu de Suerre” and walked on a short rocky path into the forest. We were collecting for a while at a nest of Pheidole ants, when I decided to walk further up the trail. I started to hear the sound of the distinctive ant birds that follow army ant raids, and sure enough came across a massive raid of Labidus praedator.
Associated with these ants was a huge assortment of flies, in incredible numbers. Clouds of tachinids and conopids (Stylogaster) were buzzing around the undergrowth, while closer inspection showed that there were equivalent masses of phorid flies a few millimeters above the ground, attacking the ants. We were collecting 5 or 6 flies per aspirator attempt without even looking, just waving her aspirator is blindly around the ants and sucking in air. We collected hundreds of flies, truly an amazing event, and one I have rarely been lucky enough to stumble upon.
The flies included several species of Apocephalus ant decapitating flies, with the most common being A. praedator. As well, we collected some highly host-specific phorid genera like Cremersia that are associated strictly with non-Eciton army ants. One of the amazing things about Cremersia is that their ovipositors are complicated and asymmetrical. We don’t know how they use them, but they are so unusual that the females were originally described as males!
Today is our last field day for this trip. There is still time for another dream to come true.
Being in the field, it is hard to ignore the biting flies. Mosquitoes, black flies, horse flies, sand flies, and no-see-ums all make their mark. Sometimes I forget, however, that humans are not the only recipients of their unwanted attention. For example, my good friend Dr. Art Borkent studies a group of flies called the Corethrellidae, whose mosquito-like females feed on frogs and are attracted to frog calls. But Art’s main study group are the aforementioned no-see-ums, technically known as Ceratopogonidae. The many species of these minute flies have differing ways of life, as some are predators of other insects, some are misery inducing biters of vertebrates (especially on beaches, where they can clear the humans out during certain times of day), and surprisingly, some feed on the “blood” (haemolymph) of other insects.
We saw a spectacular example of this yesterday here in Costa Rica. We took a day trip to a spot called Las Minas, where we were looking (mostly unsuccessfully) for different ant-decapitating flies. While searching around, Wendy Porras, our Costa Rican colleague, found a katydid with something strange on it. Being an excellent field biologist, Wendy immediately recognized that this white, almost pea-sized attachment to the katydid’s abdomen was a swollen female ceratopogonid, full of eggs.
I hope Art will forgive me, but I didn’t collect the specimen. I got distracted by other things, and by the time I thought of it, the fly had already left. This is a case of bad field work on my part. Certainly when significantly unusual things are seen, they should be collected so that the specimens accompany the life history observations. Hopefully we can make up for it with even more significant observations on the phorid flies that we came here to study.
[Thanks to A. Borkent for a couple of corrections to the original post]