Hover fly ID please

[Jason Green]

Thanks Jane,

It's female. The hind femora shows at least half yellow and probably more (only in your third image can you see this), so I'd say Syrphus cf. ribesii (the CF-bit is Latin meaning 'to consider', which is used when an identification is possible but can't be confirmed - in this case we'd need a full view of the hind leg).

The males are harder to distinguish, having similar shading on the back legs. Still, Syrphus torvus can be distinguished from ribesii and virtipennis by the hair on the eyes (he has more than the female), and Syrphus vitripennis needs to be confirmed under the microscope.

[JRsbugs]

Oh yes it is female, I didn't think the pic would enlarge more! I can see yellow hind femora through the wing in the first of the last pics, so you are safe as far as I'm concerned with Syrphus ribesii.

[Jason Green]

...yes probably, now we can see the hind leg

[Janenat]

Thanks both of you for the info, I'm quite sure there's a lot more to it but as a beginners guide have I got the gist?

Genus: Syrphus denoted by size shape and markings
3 sub species:
Ribesii
Torvus - hairier - round eyes
Vitripennis - need microscope to differentiate

Differences between male and female:
Space between eyes
Colour of frons
Difference in amount of yellow and black on legs

Any other obvious differences?

I'm assuming each genus has it's own variants, I think I read somewhere there were 276 different species of Hover fly

As always appreciate the feed back

Many thanks
Jane

[Jason Green]

Originally Posted by Janenat

Genus: Syrphus denoted by size shape and markings
3 sub species:
Ribesii
Torvus - hairier - round eyes
Vitripennis - need microscope to differentiate

The hairy eyes and microscope bit are correct. Now, Syrphus is the Genus, and then you call the second bit the Species. Both parts, ie Syrphus ribesii, is also called the Species.

As for sub-species, I don't know how that works with Syrphids - that's usually a way of explaining different forms found geographically either nationally or internationally.

Originally Posted by Janenat

Differences between male and female:
Space between eyes
Colour of frons
Difference in amount of yellow and black on legs

Any other obvious differences?

As for sexing, generally yes - a gap signifies females. However, this isn't always clear-cut. The male of Syritta pipiens has the touching at the only at the front as opposed to above by the ocelii (the light-sensing organs on the back of the head's top surface - three tiny round markings) and subsequently reveals the frons colour too (which is usually obscured in this area in males as more of the eye-margins come together).

The amount of black may vary between sexes, and the clarity of it may be affected by photographic angle - in some species (unless you mean in the Syrphus genus!), there isn't any black on the legs. The frons colour being used isn't something I've heard of.

I'll let you know of any others.

[JRsbugs]

Jane, with looking at lots of fly pics in the proper places you will eventually pick up on a lot of the smaller details.

There are characters which you don't normally see mentioned which the experts know through experience, and they have detailed keys.

Here's links to the other Syrphus sp. we have, (S. rectus on the Hoverfly Recording Scheme hasn't any presence as yet so you could really ignore that one)

Entomology Collection > Syrphus torvus

Entomology Collection > Syrphus vitripennis

Go through the picture Gallery on diptera.info to familiarise yourself with all the different types of syrphids, and other families.

There are other sites which are useful, but beware of those which will have wrongly identified flies no matter how professional the site looks. You will eventually get to know which they are.

Syrphidae

The world of Syrphidae ...

GENRES DIPTERA SYRPHIDAE

Now all you need is the book on Syrphidae, which I don't yet have! I need one... This gives some of the finer details such as frons and leg colour etc. but with many there are other obvious characters by which you can ID a syrphid. It's when you get to such as Platycheirus and Cheilosia you hit a snag, with some it's not possible without a specimen and I don't do that. It depends on how you view what you are doing, personally I just like to know what I have but if I can't find it for certain then that's OK by me, the fly can go on it's way and do what it was meant to do. I just take their pics then try to ID them.

[Janenat]

[quote=Jason Green;663894] Now, Syrphus is the Genus, and then you call the second bit the Species. Both parts, ie Syrphus ribesii, is also called the Species.

Thanks for the clarification, probably obvious to others, but can be confusing to a newbie!

Thanks again, I shall look forward to trying to ID my next victim!

Jane

[Janenat]

I'm sorry Janet I missed your reply on Friday ( not sure how!) Thank you for the info and links, now bookmarked so can go straight to them . Beginning to notice difference in species after just a few weeks so there's hope for me yet Although gardening now takes twice as long cos I have to keep stopping to take a photo of another interesting insect!
Thanks again
Jane