Ever poss to ID S.vitripennis from pics?

[Dillybythesea]

I find myself taking endless pics of Syrphus 'torvusorvitripennis', in the hope I will be able to see eye hairs and call it S.torvus. And I'm just wondering if a lack of visible eye hairs, in enough angles, is ever enough to say it must be S.vitripennis, or would it take microscopic photography to be sure of the negative? Today's example... advice appreciated!

[Matt Smith]

The eye hairs are very small, though obvious at the right magnification, which is a fair bit higher than what you have on your pictures. I have looked at literally 100's of Syrphus specimens and only ever seen a couple of S.torvus myself, though the hairs are obvious under a 20X scope.

[Dillybythesea]

Many thanks Matt. That puts me out of my misery. I won't waste any more hours playing that game! Good to know!

[Jason Green]

Originally Posted by Matt Smith

I have looked at literally 100's of Syrphus specimens and only ever seen a couple of S.torvus myself, though the hairs are obvious under a 20X scope.

Lucky you - I have yet to see my first torvus! I hear they peak early in the season and again in October. I find ribesii and vitripennis to be pretty closely-numbered during June/July.

Just the right approach, Rhona.

[JRsbugs]

I get Syrphus torvus every year now, it has a much deeper gold colour on the face and thorax hairs. Once you've seen one it becomes easier to recognise them, they do look different!

You can see the hairs on this female, not only those visible at the bottom edge of the eye but you can see a mottly effect over the eye surface which indicates hairs. This is something you learn to recognise but only if the photos are clear and close enough to show it. There's also a small 'haze' visible on the top edges of the eyes, I know there is no blur on this photo but that is something to be wary of as if slightly out of focus you can get a shadow effect.

[Dillybythesea]

That is SO helpful Janet. I can quite see it looks a different proposition entirely. It makes me think I should be able to label all my non-ribesii 'S. vitripennis'. Except I probably can't, can I!

[JRsbugs]

Give yourself time and more experience and you might be able to do it, sometimes.

[Dillybythesea]

I shall travel in hope!

[Jason Green]

Originally Posted by Dillybythesea

That is SO helpful Janet. I can quite see it looks a different proposition entirely. It makes me think I should be able to label all my non-ribesii 'S. vitripennis'. Except I probably can't, can I!

Unfortunately their physicality is pretty variable. The wing microtrichia (tiny wing-hairs) is marked and, with a little experience and lighting of a perfect angle of incidence, is a readily-used and obvious characteristic. Now, I just 'comatose' a specimen, check it then release. If you really want to, you could take one in a lidded petri-dish, briefly refridgerate then examine under a microscope (20x models for about £40 on Amazon, etc.).

It's not as difficult or out-of-reach as it may feel - just prohibitive, if you limit your equipment to only a camera.

[Dillybythesea]

Thanks Jason. That sounds a very viable possibility! I shall look into it forthwith!