Closer crop, 0.59 mm high on subject:
This is the very tip of a particular kind of wasp antenna, and one that I think is pretty unusual.
This wasp is one of the mud daubers that I presented at http://www.photomacrography.net/forum/v ... hp?t=37174 .
What prompted me to look closely at the antenna were the pictures in that previous thread, particularly the ones in THIS posting.
Here are a couple of examples:
If you look through those pictures, you'll see that some of the antennae are very sharp, some are the usual blunt shape, and there's no clue why there should be some of one and some of the other.
Initially I thought it was just the gender of the wasp, as suggested by the overall body shapes shown above. But that turned out to be wrong.
The real answer turns out to be that sharp or not is at the option of the wasp. The ends of these wasps's antennae have an articulated section, which can be either extended to produce the sharp outline, or retracted to produce the blunt one.
This is the first time that I have ever encountered this structure, but I have to confess that I don't know whether it really is unusual or not. I've looked at a bunch of wasps of a different kind (Polistes dominula) under stereo scope, and I don't see anything like it. But the articulated section is not simple to see when retracted, and maybe I'm just overlooking it. I've also tried Google image searching on "wasp sharp antenna", and I don't see any images that show similar sharp ends. But who knows what that means?
In all the specimens I had, the articulated segment was completely retracted after the subject was dead. To make this image, I had to carefully fish out the retractable segment while the specimen was still fresh, and hold it out by shoving an insect pin into the notch while the specimen dried. Not a simple mount!
If anybody knows about these articulated ends, I would appreciate learning!
For those interested in technique...
Shot with Mitutoyo M Plan Apo 10X NA 0.28 objective with Raynox DCR-150 tube lens, so nominal 10.4X magnification. Canon T1i camera, 15.1 megapixels (4752 x 3168) on 22.3mm x 14.9mm sensor, ISO 100, 1/12 second with diffused Jansjö lighting (3 lamps). 82 frames, 0.005 mm focus step. Shot in portrait orientation, cropped in StereoPhoto Maker to 2758 pixels high for the first image and 1302 pixels high for the second, then resized for posting. Processed in Zerene Stacker with DMap, stereo separation +-1.4%, which for this stack works out to be 5.6 degrees of stereo separation. No retouching.
Here is the setup for shooting. For purposes of aiming I shined a small LED lamp down the eyepiece so as to light up the FOV. The tip of the antenna is bright white in this view because that's the part that was illuminated by the aiming light. Rough positioning of the mounting block was done by rotating in hand under a stereo scope, reproducing that orientation in the high mag setup by pinning the block, then tweaking it with rotary table and goniometer in the positioning stack.
I hope you find some part of this interesting.
Anybody who knows more about the articulating segment, please share!
--Rik
Edit: to fix spelling error in scientific name
Edit: remove question mark from title: "Unusual(?)" --> "Unusual"
