Tiny winged ant showing interference colors

Images taken in a controlled environment or with a posed subject. All subject types.

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rjlittlefield
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Tiny winged ant showing interference colors

Post by rjlittlefield »

Let's start with the crossed-eye stereo:

2020-08-23-11.19.21-ZS-stereo-_000_cropped_small.jpg


A bit closer crop from the same stack:

2020-08-20-20.45.06-ZS-retouched_cropped_small.jpg


Now, here's the ant in more conventional presentations:

2020-08-20-17.55.09-ZS-retouched_small.jpg

2020-08-20-21.00.15-ZS-retouched_small.jpg


There's a story here, of course.

A few nights ago I was eating dinner outside, when a tiny winged thing dropped onto my plate and started walking around. At first I thought "fly?", but that didn't look quite right. Then I thought "wasp?" but that didn't look right either. Finally I hauled out my always present 10X loupe and took a look through that. "How strange!" I remember thinking, "That looks ever so much like a winged ant. But so tiny?!" I watched it for a while, wondering if I had enough time and enthusiasm to try photographing it. That seemed like a lot of trouble with little chance of success. But after a while it walked into a drop of liquid, got caught there, and became fair game for harvesting. That made life a lot simpler. So I prepared a vial of alcohol, transferred it to that, and finished my dinner.

Later, under a stereo microscope, I considered what I had.

Sure enough, it seems to be a winged ant (note the node on the petiole). But it's the tiniest one I have ever seen, body length 1.9 mm! Seems to be male, so it's probably smaller than average, but even so I can't figure out what sort of ant it would be at that size and shape. We do have some small ants, but they're black and have elaborate sculpturing on the head. Naively I would not expect a winged male to look that different. If anybody knows about this, please let me know too!

Then of course since I had the specimen, I had to figure out how to work with it. I don't normally work with things this small and fragile, so I don't know any of the standard techniques. Finally I switched it to acetone, dipped it out along with some of the liquid, placed it in the center of a well slide, rolled it around until its wings were sort of spread, then dropped a cover slip on top over the well so it would stay that way as it dried. After all the acetone was gone (several hours), I removed the cover clip and glued the specimen to a paper point with water soluble glue so I can get it loose again in the unlikely event I ever want to.

Of course nothing even works quite right. The one thing that I really wanted to get a picture of was the node on the petiole, and in the posture the beast had dried, the big part of the abdomen had nestled up around the node so it wasn't really clear there even was a node. A bit of water on the abdomen softened it enough that I could bend the abdomen down to expose the node, and I decided that was good enough.

So then I mounted up the beast to get a good angle on the node, set up with a Mitutoyo 10X on Raynox DCR-150 which provided a usable combination of sharpness and DOF, and shot a 192 frame stack (0.007 mm focus step) of the body and the wings close to it. I used a black background just to minimize glare and get best separation for the node, but after I processed the stack and looked at the whole image, I was surprised to notice some interesting colors on the wings against black background.

Of course I got interested in the colors. So to make it feasible to shoot the whole ant, I backed off to a 5X objective, found that I could stretch the focus step to 0.050 mm and still get a good result, and shot a 172-frame stack (total depth 8.6 mm) and processed that up to make the stereo pair that starts this post.

Then I got to thinking about what the post would look like. I decided that if I were reading it, I would want to know what the ant looked like in more conventional presentations, hence the two flat views.

Other interesting stuff, um, Nikon D800E, two Jansjö lamps diffused through Kleenex tissue. Mostly DMap, a little editing from PMax slabs done in stereo using Stack Selected specifically to cover troublesome areas.

Anything else?

Oh yeah, maybe I should show the node on the petiole that I wanted in the first place. Here's that:

2020-08-23-16.50.40-ZS-stereo-_000_cropped_small.jpg


--Rik

MarkSturtevant
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Re: Tiny winged ant showing interference colors

Post by MarkSturtevant »

That is neat. So the iridescent effect comes out in the dark-field set up. Probably in bright field, all that extra light bouncing around just washes it out.
Mark Sturtevant
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Re: Tiny winged ant showing interference colors

Post by BugEZ »

Very interesting Rik!

Many years ago I recall watching winged ants swarm up from the ground in a steady stream. They did this in the Arizona desert right after a big rainstorm. They were small ants, but bigger than this.

Thanks for sharing!

Keith

rjlittlefield
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Re: Tiny winged ant showing interference colors

Post by rjlittlefield »

Thanks for the feedback!
MarkSturtevant wrote:
Sun Aug 23, 2020 8:40 pm
So the iridescent effect comes out in the dark-field set up. Probably in bright field, all that extra light bouncing around just washes it out.
Yes, that's my interpretation. The colored reflections are only a small amount of light, probably down in the single digit percentages compared to white. The result is that when lots of non-colored light is added, via white background and transmission through the transparent wing, almost all the contrast is lost and the iridescence becomes just a slight color cast, difficult to see even when looking for it.

We can make a crude attempt at "subtracting out" that extra white light, by applying a strong levels adjustment to just the bright side of an earlier dark/bright image. With that adjustment, we can start to see that the colors on the dark side are mirrored on the bright side:

LevelsAdjustOnWhiteSide.jpg

By the way, here's an overview of the setup for the first image in the original post.

IMG_9579-WingedAntSetup.jpg

--Rik

PS. I've posted an ID request at "The Ant Farm and Myrmecology Forum", https://www.tapatalk.com/groups/antfarm/id-please-richland-washington-state-usa-8-17-2020--t20678.html

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