Unknown processes on tarsi of anthomyiid fly

[flynet]

Pegomya rufina (Fall.) is a Palaeartic species of Anthomyiidae. The female (not the male) has two small 'boomerang' processes on the last segment of the tarsi ventrally. As far as I know this has not been mentioned in the literature. The purpose of these processes is unknown.

Following my progress in learning to take photos through the microscope, I have taken a shot of this structure at a magnification of X400, which I have not used before. My first attempts, with the tarsus in glycerine jelly in a cavity slide, were rather difficult, as too deep, and resulted in getting the X40 objective covered in jelly!

So I placed a small blob of jelly on a plain slide, and after inserting the tarsus, put a coverslip on top. By pressing slightly on the coverslip the tarsus, claws and pulvilli together with the processes on the last tarsal segment, were nicely flattened, and have made a reasonable photo.

I notice that many fewer stacking shots were needed, compared with my original oblique view which had a greater depth of field.

I found some very instructive threads on the subject of cleaning slides and coverslips on this site. What a resource!

Incidentally this photo is made from two sets of stacks, joined with the PSE12 panoramic facility. I need a X6 or 7 objective, as X4 is too low and X10 needs this stitching together. Anyone got one for sale?

[Pau]

Following my progress in learning to take photos through the microscope, I have taken a shot of this structure at a magnification of X400, which I have not used before. My first attempts, with the tarsus in glycerine jelly in a cavity slide, were rather difficult, as too deep, and resulted in getting the X40 objective covered in jelly!

So I placed a small blob of jelly on a plain slide, and after inserting the tarsus, put a coverslip on top. By pressing slightly on the coverslip the tarsus, claws and pulvilli together with the processes on the last tarsal segment, were nicely flattened, and have made a reasonable photo.

The first approach only would work with Long Working Distance objectives (most 4X and 10X have pretty long WD but most higher magnification ones except if marked LWD or ELWD not)
In any case your second approach is the right one with biological microscopes, not only to avoid dipping the objective but also to get better IQ: flat surface, less sperical aberration...

[flynet]

Thanks for your comments Pau.

I have 2 old Watson objectives on an old monocular marked 2/3 in and 1 in. Is ir possible to say what magnification they are approximately?

The X40 modern objective used in the photo has a very short working distance. It's marked: 40/0.65, 160/0.17. The 160 is the tube length?

[Pau]

I have 2 old Watson objectives on an old monocular marked 2/3 in and 1 in. Is ir possible to say what magnification they are approximately?

The X40 modern objective used in the photo has a very short working distance. It's marked: 40/0.65, 160/0.17. The 160 is the tube length?

Yes, 160 is the DIN standard tube length in mm, /0.17 indicates that it must be used with a standard 0.17 mm cover slip

About your old Watson, no idea. Some old objectives indicate the focal lenght and not magnification, but I don't know about these marks.

[Alan Wood]

I have a Watson objective that is marked 2/3 in on one side and 10× on the other side.

Alan Wood

[ChrisR]

That "figures", in as much as 2/3rds inch =~16mm which is right for 10x.

[flynet]

You are quite right Alan. I had another look under a stereo and on the other side it says X10. Almost invisible with the naked eye and almost black. I was hoping it would be about X7, as I have a modern X10 which is much better.

Thank you both for your replies