Hoverfly for ID, please

[jeremiah]

Is this Syrphus ribesii?

It was sitting on the leaf making a loud, high-pitched buzzing. I had a good look at it, from close up (and it didn't fly away!), but I couldn't see anything vibrating. How do they make the buzzing noise?
When it finally took off it went past my ear like a little bullet - do they jump into flight?

[Jason Green]

Evening Jeremiah,

This could be something like Epistrophe grossulariae, based on the face.

As for ribesii-types, you can't always get better than Syrphus sp. from field photos, I'm afraid! We have four - Syrphus torvus, S. ribesii, vitripennis and rectus...

- torvus has hairy eyes (which would hopefully show in a great photo)

- ribessi and vitripennis lack this and can be seperated by genitalia and microscopic differences between their wings (leg colour can help - but isn't necessarily definitive! The hind femora has to be more than 60% dark I believe to consider it, and even ribesii can show varying dark lengths)

- rectus is rare with only about six records - under-recording and I think recently discovered on genitalia? Not sure

The buzzing will have been it warming up. They can take off pretty sharpish, can't they!

Take care,

Jason

[jeremiah]

Thank you for the information, Jason.

I've looked in the Gallery, and in google images, and to be honest I can't tell the difference between Epistrophe and Syrphus, let alone any difference between the different Syrphus species.

What do they use to warm themselves up? Are they vibrating something other than their wings? Because I was watching it and its wings weren't moving while it buzzed.

[Roger Morris]

Hello

This is not E. grossulariae - it is one of the four Syrphus but I cannot say which.

I think you also posted a photo of Baccha elongata - correct - would it be possible to supply the data - site, date, grid ref or postcode and recorder please? The recording scheme welcomes all contributions.

Regards

Roger Morris

[jeremiah]

The Baccha elongata wasn't me, gov : Baccha elongata?

I've done a little google searching and found a reference to the buzzing when stationary, in the International Wildlife Encyclopedia:

"Another curious habit hoverflies have is of continuing to buzz once they have settled and ceased to move their wings. The sound seems to be produced by vibration of the thorax, but why they do this is not known."

And I must say - given the list of identification criteria above (thighs, hairy eyes, basal wing cell hairiness I saw mentioned somewhere = armpits?, plus other more unmentionable bits) - peering at it would make any hoverfly shy; perhaps that professor has a point about animals having a right to privacy?