CLOSED: Can I be sure this is an Eristalis arbustorum female?

I'm hesitating as pics I see of the female still have a broken band of orange-brown on the top of the abdomen while this one has none..
But all the rest fits including the legs..

It looks like E. interruptus to me.

Not E. interruptus, that has a very well defined small spot on the wing where the dark mark is on the outer edge. There was a key once but it has been taken off the internet, and I had it sent to me by someone who had the link for it but I lost that in the computer crash!

E. pertinax is a possibility as it has yellow on the top section of the hind tibia, but the tarsi (feet) need to be seen well as they are orange for this species. It is a female and their tail end is not so pointed as the males. Another similar one is E. jugorum which I think has black feet. Best perhaps to try the dipterists.

This message was edited Dec 2, 2008 6:29 PM

Thanks Enmos and Wallaby!
Yes, I think the wisest would be to ask it on the Diptera site, I have another doubtful case of a female but on that one one can still see a very faint dull sign of a broken orange-brown band on top of the abdomen..

I have been labelling mine the last two days too, I have some dubious ones also. One with no white cross bands but has no yellow marks either, there is a faint hint of marks which I can see on yours. The cold season may have something to do with that, I have one which has to be E. tenax female but the tail is very short, it looks very chubby, lol!

Here is an explanation of the bicoloured tibia (as I mentioned) for E. pertinax. It also mentions the white distended abdominal bands, but they can do that when a female is heavily pregnant or for other reasons. I have some too, but the yellow on the hind tibia indicates E. pertinax IF the front feet are orange/yellowish. If not, it would be E. jugorum as that can have dull, indented tergites on the abdomen but so can E. pertinax. E. pertinax is the most common.

http://www.bugsandweeds.co.uk/hoverflies.html

I've posted it to the Diptera site, but didn't get an answer yet..

I see what you mean with the bi-coloured tibiae of the hind legs, but then I noticed that the female of E.arbustorum has that too!

http://diptera.info/photogallery.php?photo_id=193
But its true that the female E.pertinax matches better with mine, apart from that lacking broken orange-brown band.

These are the two other flies I think are the same specie I've possted also on the Diptera site;

This one has a little bit of the band;

The tibia on E. arbustorum is more cream than yellow, and the abdomen is shorter, but sometimes the differences are not so easy to see! I think your last one is E. arbustorum, the white lines are more pronounced and the abdomen looks shorter although very rounded, it could be laden with eggs.

Here's one of my E. arbustorum from this year, I have one which I'm not sure about either! If they are not obvious I just go with the ones which do look correct, lol.

This was on 27th September.

Just noticed that my second picture didn't come through, though I'm sure I did post it, weird!

Yours looks very shiny and pretty! and indeed there cannot be any doubt about its ID!
I should take your advise only to go with the ones which are obvious, but still it annoys me if I cannot give them a name, lol!
Hope I'll get an answer from the Diptera site..

This was the other one on 30 th November;

That looks like E. arbustorum too, the colouring on all the legs I have noticed always is cream with black, and the feet are black (but more on top). The face is always pale with no stripe down the middle, and thorax is a light brown. E. pertinax has a well defined black stripe down the centre of the face, orangey front feet, and the thorax is more orangey brown.

Ah I found another picture of the same fly with the face visible though not very sharp.
Not sure though if the face is entirely whitish or if I see something blackish in the middle of its face..

It is very difficult to tell from that still, lol, I am veering towards E. arbustorum but then E. pertinax doesn't always show a very dark stripe on the face either as I have found with mine from some angles. The dark line isn't spread like it is on E. tenax.

It's still not easy to see the feet either. I have one which for all the world looked like E. tenax but after looking at many shots I took, I came to the conclusion it had to be E. pertinax, as I could see the orange feet well in one pic. From some angles I could see it was pregnant too, making the abdomen look fatter, and the thorax hairs were also paler than usual! The hind tibia did have some very pale area but I wasn't sure in some pics from the angle, and the sun as well as age can make a big difference so in the end it had to be the feet which told me, lol.

This is a female E. arbustorum with the said E. pertinax on 1st May. The mlae came in too with the female E. pertinax and he followed her to each flower she visited, lol! I think he was confused!

Now here is one with the male E. arbustorum, and the hind leg on E. pertinax from this angle looks all dark but it just isn't showing it.

One thing I have noticed is the more 'closeness' of the eyes of the female E. arbustorum than yours has, the distance between the eyes of E. pertinax looks much bigger, and it does have that dark black-tawny lot of hairs at the top between the eyes. That is making me lean very much towards E. pertinax!

Another thing I have noticed with E. arbustorum is the legs always look quite hairy, where E. pertinax has bare looking legs. Yours look bare.

Here's one of mine from 2nd October, this is E. pertinax female! All it needed to look like yours was some distending of the abdomen.

The alternative is there are quite a few more Eristalis species, lol, if not happy with anything fitting properly into place then it really is best to leave it open. I know how you feel wanting to give it a name though, lol, been there myself but I think I'm now controlling my insect NO ID urges!

I think I'd better take your advice on the first one and keep it in a map with unsure ID! I will have to learn that, lol!

"The male came in too with the female E. pertinax and he followed her to each flower she visited, lol! I think he was confused!"

Lol! If he has difficulties to tell them apart what about us then!
He should have looked at her feet ! lol!

"Another thing I have noticed with E. arbustorum is the legs always look quite hairy, where E. pertinax has bare looking legs. Yours look bare."

Yes that's correct, its legs don't look so hairy like from the others.

I noticed that the male E.arbustorum in your second picture has quite bare legs, so with this specie it must be only the female that has these hairy legs ?

yours of the 2nd October doesn't seem to have the white bands on the abdomen so pronounced, they're rather faint, but then perhaps it was more relaxed like they explain in the Bugs and Weeds site and mine probably also expanded because it was pregnant..

Yes to all of that, Lol! Except the male E. arbustorum was probably an old one, it's thorax looks a little bare too. I'm not sure but I think they overwinter, there's always a fresh lot in the autumn. It's more the tops of the legs which are hairy and there isn't much visible but I can see some hair hanging down.

I had to search to see what I could find out about them overwintering, it seems those which eat aphids go south! A long way! If you use the 'edit' tab and 'Find in top window' using the word 'overwinter' you will find it.

"Tenkumberg and Poehling [15] reported that the aphidophagous species of hoverflies migrate to overwintering sites in southern Europe or northern Africa and come back to northern regions in spring when their food plants flower and aphid populations develop."

http://www.ejpau.media.pl/volume7/issue2/biology/art-08.html

LOL to the feet! Maybe he likes orange feet, lol!

I don't have that 'edit' tab in my browser but found something that worked as good; its called 'find on this page' in the menu.
I had never used that feature before but now it will proof very useful in the future! Thanks!

I would ever have thought them going to warmer regions in the winter (like some butterflies and birds) They must find food on the way to keep them going so far!

"Maybe he likes orange feet"
LOL! Now that brings up the idea that my questionable one could be the result of a 'mistake'. I wonder if they can cross with each other..

Still found another one on the same flower Tanacetum vulgare, but on another date (19th September). It also has no broken orange band on the top of its abdomen, but some very faint suggestion of that. But the white bands on this one look a little more pronounced and I think its feet are black and the face has no black stripe, and it does have hairy legs, so that one must really be a female E.arbustorum.

side view of the same where the face is quite visible.

It looks quite hairy all over...

You got it! Lol, I have often wondered the same about Dragonflies, there is a pic of two different species mating on the UK Dragonfly site and they hadn't noticed it until a reader pointed it out! Some Dragonflies just LOOK like a cross, lol, it does seem possible with those at least so perhaps it is with Eristalis.

Now I will have to search to see what I can find about that, lol, some species make it impossible to breed.

Thanks!:)

As they belong to the same family Syrphidae, perhaps it is!