Is this Chrysotoxum cautum or elegans

[ChrisR]

Originally Posted by JRsbugs

Fair enough, the person who confirmed it usually doesn't make mistakes, nor does he confirm IDs if he is at all uncertain but on this occasion maybe he made a mistake.

Perhaps revive the thread of DI and ask Andre politely why he was so sure about the ID and why he discounted luniger? I am sure he'd be happy to clarify his ID and we can judge whether it was an off-day for him

[Roger Morris]

Hello everyone

In terms of and ID thread, my recommendation would be to sign up to the Hoverfly Recording Scheme website Hoverfly Recording Scheme - Index - I've always dealt with records there and there are several others who regularly trawl the site and provide advice. The shot can then be posted on Wild About Britain with more confidence. However, I will keep an eye on records and give opinions from time-to-time.

Going back to the general principles of ID from photos, I'm afraid I hold quite a bit of sceptocism about ID from photos. At a personal level I quite frequently find myself saying "I am just not sure because I want to see x or y". Maybe I'm just not sufficiently competent but I generally avoid doing field identifications on many of the difficult genera. In the case of Eupeodes for example, it is a bit of a nightmare genus with small characters that are not revealed in photos e.g. microtrichia on the wings. I know some people exude great confidence about ID of photos, and I confess I would err towards the same ID. But, I'm afraid I have also found that I've been wrong - so I don't put a name to anything that might be confused with something else.

Stuart Ball and I have developed a classification of ease of identification which shows just how tricky we and other specialists regard hoverflies. In tyhe Case of E. lapponicus I think we would expect to see a specimen because it is just too tricky.

Regards

Roger

[ChrisR]

I agree with Roger ... with the tachinids we have often discussed how many field-identifiable tachs there are in the UK and it always comes down to a very small % of the 270-odd species you could possibly find here.

One of the main issues is that most photographers are happy to accept a name with a much lower degree of certainty than, for instance, a recording scheme would. Looking at a photo you can always say what the fly *looks* like ... but seldom can you actually say what it *is* because the characters that really define the species are usually so small.

A classic example of this is the very common species Phania funesta, which is very easy to ID from photos ... except that it can only be split from its very rare cousin P.thoracica by examining a specimen under a microscope. If we take loads of photo-records then we would be meerly guessing (even if we were correct 99% of the time) and it would artificially bias the recordset towards the common species and we wouldn't notice a potential increase in the population of P.thoracica.

Also, recently Dipterists like Ivan Perry have discovered quite a few new species by closely examining specimens that would otherwise have been given the name of an existing UK species because they look very similar. Only when you run a lot of material through European keys do you come up with these newcomers - or in the case of Linnaemya picta, find that a well-known colony has been misidentified for decades.

[Jason Green]

Originally Posted by ChrisR

Perhaps revive the thread of DI and ask Andre politely why he was so sure about the ID and why he discounted luniger? I am sure he'd be happy to clarify his ID and we can judge whether it was an off-day for him

I'd like to know too - surely luniger would jump out strongly??

[JRsbugs]

I'm not sure what the best line of approach here is. I had thought of privately mailing Andre to ask what his ID criteria was, he may have had an off day but then again not. I'm no expert, I just go on what I see and what I have learned but I try not to push what I see without the vital evidence. Take for example one I had identified recently on which the vital feature could be seen, that is short setulae on the inside of the foreleg femora of a Lauxaniidae Meiosimyza rorida. Two worldwide experts egreed without doubt because this feature was visible, and I have found that no-one on this site will identify anything without being able to see something which excludes other species.

Diptera.info - Discussion Forum: Lauxaniidae Meiosimyza rorida?

Yes, on the odd occasion someone has an off day as we all do. I may have to bring up the thread 'gently' in order to see what is said as Chris has suggested.

One point about taking IDs from pics, I must say that in a good number of cases a fly would not have been caught, or in my case I don't want to catch them. This surely gives rise to many valid records which otherwise would have been missed. With the improvement of digital camers, combined with an individual's passion and desire to take photos, this has to be a bonus to any recording scheme.

I went to the trouble earlier this year to sell a lot of items I had and did not want on ebay to raise the money to buy a good macro lens and a teleconverter, and believe me I had more hassle than anyone would want in a lifetime with a subtle but vicious fraud attempt, apart from the usual problematic people.

My interest is first in getting good pics, but I wanted to get those smaller flies more than anything in good detail hence the move to macro and manual photography which to anyone who has not used a DSLR before was a huge leap. Of course then getting to know what I have is great, and helping recorders to know what there is here is the icing on the cake I would say.

I have thought about the best approach of getting my flies either identified (or confirmed for the easier ones). My thoughts for the Syrphids were to start a thread here in order that a good number of other people may be able to view them and perhaps also be encouraged to take a closer look at what they have in their areas. This could have a rollercoast effect as I'm sure there are many people who would like to do this but feel a little discouraged because of the enormity of it all. I would like to say to those people, do it and see, I started not many years ago and knew nothing.

In the past I have taken my uncertain flies to Diptera.info, I feel relatively at home there and now I can take better pics I have a far better chance of getting IDs. I have at the moment around 700 pics in my Syrphid fly folder from spring this year , of course not all different species! This is going to take me some time, apart from these I have probably got close on 3,000 pics of other flies in the same period! Then there's the bees, beetle etc... yes I take everything that moves!

Let me stew on it a while....

"I'd like to know too - surely luniger would jump out strongly?? "

Jason, yes that is what I thought about E. luniger, I must admit it had not even entered my head that it could be that. And E. luniger is one which I have been familiar with from the outset. But at the same time I admit to not being an expert and understand the problems which can arise.

[Geoff F]

I had thought that this old thread would be well past it's 'sell by date' now, but it has suddenly sprung into a round of new life. And extremely interesting it is.

Charlieb, that Devon Wildlife Recording Centre is where I had started sending my records. Usually they replied to ask for the photos for double checking my suggested ID's. Then they started requiring expert ID before submission and, so far, I haven't sent in anything else; but I haven't really seen much of interest lately anyway.

Roger, I am currently checking through my images of the past 2 years so I will put together my confirmed sightings with definite locations and send it on to you. While there is little of any real excitement here, hopefully it might fill in a few missing holes in the location squares.

[ChrisR]

Originally Posted by JRsbugs

I'm not sure what the best line of approach here is. I had thought of privately mailing Andre to ask what his ID criteria was, he may have had an off day but then again not.

Well, I doubt he would be upset if you just asked for clarification - you want to learn the differences yourself and any expert should be able to justify their IDs

One point about taking IDs from pics, I must say that in a good number of cases a fly would not have been caught, or in my case I don't want to catch them. This surely gives rise to many valid records which otherwise would have been missed. With the improvement of digital camers, combined with an individual's passion and desire to take photos, this has to be a bonus to any recording scheme.

Well, I have to be careful here because I enjoy giving out identifications for photos (if I can) and there are obviously species that are so distinctive and so unlikely to be anything else (e.g. Tachina grossa, Mintho rufiventris, Eriothrix rufomaculata etc.) that the record would probably be accepted.

But, for instance, if you post a normal photo of a Phryxe sp. with parafrontal bristles almost meeting the facial-ridge bristles then I'd have to say that it looks like Phryxe vulgaris ... but I can't disprove P.heraclei because I can't see the bristlets on the underside of the costal vein and I can't discount P.magnicornis because I can't see the male genitalia - so I wouldn't accept it as a record. Same goes for the Phania funesta example - I am going to be right 99% of the time but I can't discount P.thoracica because I can't count the tibial spurs on the hind legs, so I wouldn't take the record again

[Roger Morris]

Yes you are so right Jason - just the right approach. All records are useful. It does strike me that there may be a benefit from developing a theme on this issue - would you be prepared to start one - I am a bit of a luddite and as yet don't know how!

By the way, I've just spent two days going through all of the photos on Wild About Britain and have extracted usable data from 143 entries that we had not found elsewhere. Nothing terribly impressive but all useful. This sort of return for effort is fairly good bearing in mind the time of year - I would not be out recording! However, there were many more (probably the same again) with no data. Just by way of information here is the breakdown of records.

40 species were recorded. For most there were just single or a couple of records. The breakdown is at the end of this message. One of the most noticeable points I think is that most contributors are from southern England or the Midlands. Very few from Scotland or northern England. This seems to miror data coming in from other sources but I'm at a loss to know why - surely there are lots of field naturalists in Scotland?





Anasimyia contracta, 2; Baccha elongata, 1; Chrysotoxum bicinctum, 1; Chrysotoxum cautum, 1; Chrysotoxum elegans, 1; Chrysotoxum festivum, 2; Dasysyrphus tricinctus, 1; Dasysyrphus venustus, 2; Epistrophe grossulariae, 1; Episyrphus balteatus, 15; Eristalinus sepulchralis, 1; Eristalis arbustorum, 3; Eristalis interruptus, 2; Eristalis intricarius, 2; Eristalis pertinax, 9; Eristalis tenax, 9; Eupeodes corollae, 2; Helophilus pendulus, 18; Helophilus trivittatus, 2; Leucozona lucorum, 2; Melanostoma scalare, 3; Meliscaeva cinctella, 2; Merodon equestris, 3; Myathropa florea, 4; Platycheirus albimanus, 1; Rhingia campestris, 8; Rnhingia rostrata, 1; Scaeva pyrastri, 1; Scaeva selenitica, 1; Sericomyia silentis, 4; Sphaerophoria scripta, 2; Syritta pipiens, 1; Syrphus ribesii, 3; Tripidia scita, 1; Volucella bombylans, 8; Volucella inanis, 2; Volucella pellucens, 6; Volucella zonaria, 7; Xanthogramma pedissequum, 4; Xylota segnis, 4.

[JRsbugs]

Great going Roger.

I have started a thread for Syrphid ID and records.

RECORDS Syrphid (Hover) flies for ID

[JRsbugs]

I brought the fly in question thread up and have had a rely from someone else. This is the difference between the two, one point I did noticed when looking again was the yellow at the edge of tergite 5.

In E. lapponicus, the side margin of tergite 5 is at least partly black, while in this specimen it is entirely yellow. E. luniger is much more likely, based on the yellow side margins of tergite 5, the yellow hairs on the scutellum and the yellow abdominal spots not reaching the side margins of the tergites. Besides, the genitalia are not conspicuously large, so that rules out E. corollae.
The best character for E. lapponicus is the sinuate vein R4+5, but this is not visibe in this picture either.

Now we are all a little wiser. My eye for detail has developed more since last year too!