Syrphus vitripennis?

[PeterD]

Can anyone please confirm this?



Click for larger image.

Thanks

[Jason Green]

Evening Peter,

It could be, but the character used for confirming vitripennis is the sparse microtrichae in the basal cells, just about visible at 20x under the microscope and too gentle to be picked up by a macro-lens in the field.

The hind leg colour can be used as an aid (with females, but males of all three Syrphus spp. have shaded hind femora), but I wouldn't like to say it is without the wing under a microscope. I have with one, and have a photo of the subtlety if you'd be interested.

A nice photo, by the way.

Take care,

Jason

[PeterD]

Originally Posted by Jason Green

Evening Peter,

It could be, but the character used for confirming vitripennis is the sparse microtrichae in the basal cells, just about visible at 20x under the microscope and too gentle to be picked up by a macro-lens in the field.

The hind leg colour can be used as an aid (with females, but males of all three Syrphus spp. have shaded hind femora), but I wouldn't like to say it is without the wing under a microscope. I have with one, and have a photo of the subtlety if you'd be interested.

A nice photo, by the way.

Take care,

Jason

Thanks for your reply Jason. I would appreciate a view of the photograph. If you could provide me a link I would greatly appreciate it.

I have a few more shots that I am in the process of finalising (I shoot in RAW and need to process the result) and I could perhaps check the others against your image.

[Jason Green]

Certainly:

Now, look to the centre-half of the photo - third panel down. The microtrichae are the tiny little slightly-elongate marks at the bottom, and only positioned along the lower vein leaving most clear. This is how it is in vitripennis, and the cell is full of it in Syrphus ribesii.

Each divisional line is one vein that you'll see in your photo - the ones towards the base of the wing. Now, consider how many of the microtrichae you could fit vertically in each one! That's how subtle it is, and I doubt would show in a normal image unfortunately.

[PeterD]

Originally Posted by Jason Green

Certainly:

Now, look to the centre-half of the photo - third panel down. The microtrichae are the tiny little slightly-elongate marks at the bottom, and only positioned along the lower vein leaving most clear. This is how it is in vitripennis, and the cell is full of it in Syrphus ribesii.

Each divisional line is one vein that you'll see in your photo - the ones towards the base of the wing. Now, consider how many of the microtrichae you could fit vertically in each one! That's how subtle it is, and I doubt would show in a normal image unfortunately.

Good evening Jason
Well, thanks for that image. You know what they say - a picture is worth a thousand words It also illustrates that the only way to confirm it would be to kill the sample. Unfortunately, that goes totally against my principle of appreciating what I see without causing deliberate harm or alarm. I have accepted that clear IDs sometimes necessitate examining a sample under a microscope. I think I shall keep this one under the family name.

Thanks again

Kind regards

Peter

[Dogghound]

The hind femora stongly suggests Syrphus vitripennis.

[PeterD]

Originally Posted by Dogghound

The hind femora stongly suggests Syrphus vitripennis.

Thank you. I think, on balance, I shall go with this too.

[JRsbugs]

Jason, comparing it with Syrphus ribesii is not a good comparison. You don't need to see the wings at such fine detail, not that I could see any of those tiny hairs in your pic anyway.

Syrphus ribesii females have all yellow hind femora, or black only at the base. Same with S. rectus females.

The only other one it could be is S. torvus, for that a closer view of the eyes would be necessary.

I haven't seen S. torvus yet, but have seen S. vitripennis. On balance, and without killing the fly, the hind femora has about confirmed it to be S. vitripennis.

[Jason Green]

Originally Posted by JRsbugs

Jason, comparing it with Syrphus ribesii is not a good comparison. You don't need to see the wings at such fine detail, not that I could see any of those tiny hairs in your pic anyway.

No, I was just explaining how the two would differ - not how to confirm, I could do that in the field. What do you know about rectus?

Originally Posted by JRsbugs

I haven't seen S. torvus yet, but have seen S. vitripennis. On balance, and without killing the fly, the hind femora has about confirmed it to be S. vitripennis.

Bear in mind shadow, individual anomolies, etc. - it's probably fallible. You don't have to kill it, either - just get it comatose, examine and release

Yes, where are these torvus? I've never seen one. I'm surprised you haven't, Janet! Apparently they look bigger physically, and are common in the early part of the season. We're heading for their third peak, apparently - October, I've heard. Who'll get one first?

[PeterD]

Good morning Janet and Jason. I have uploaded a 100% crop at the eyes, if this helps.


Cheers