orchid_b's picture

Bombus vestalis/bohemicus i/d in the field

Observed: 11th August 2013 By: orchid_borchid_b’s reputation in Invertebratesorchid_b’s reputation in Invertebratesorchid_b’s reputation in Invertebratesorchid_b’s reputation in Invertebrates
IMG_8567
Description:

The commonest bumblebee about at the moment (mid-August).
This is a large cuckoo bee, instantly recognisable from all but B.bohemicus by the yellow side-flashes on the border of black/white on the abdomen. Even at a distance, the honey-coloured 'boa', the lack of a strong yellow band on the front of the abdomen, the loose thin furring of the elongated abdomen, and the thin 'shoulders' make it instantly distinguishable from the B.terrestris (mostly male) still about. The dark shading around the wing veins and the rough, thin hind tibia are visible on a close-up like this, but by the time you get close enough to see them you know what the species is anyway. Many books try and get you to do this i/d in reverse, starting with the hind tibia, but this isn't remotely necessary.
B.sylvestris female is possible, but is smaller and has a very different shape with curled-under abdomen and usually a dark tip (red in male).
You could try counting the antennal segments on this photo to sex the bee before you start - it is sharp enough and detailed enough to be easy...but it isn't! Even with the excellent illustration of a numbered antenna in the New Nat key (the only one I've found that actually gives this crucial info) showing what counts as segments 1 & 2, look at the next ones along. Is that a long segment 3, or segments 3 & 4? Or even short segments 3,4 & 5? Then look at the tip - is there another tip segment hiding below what appears to be the end? OK, now try doing all that, as recommended by many books, to a struggling bee in a specimen tube! No, counting antennal segments like many features, is fine for Dead Bees, but not much use in the field compared with other more obvious features.
So far the only way to i/d vestalis/bohemicus for sure is to pull the bee apart to look at the genitalia. All the ones done here so far have turned out to be vestalis, but the large size of this female, coupled with the honey colour on the band (cf yellow) could well turn out to be good enough field characters. The amount of yellow on the side-flashes is a difficult one to judge in the field.
The males have more yellow on the thorax - usually bands front and back, with the front extending on to the top of the head (the latter I think could be a more reliable field character than the former). Pretty much all my vestalis are females at the moment, which is odd, as the consensus is that males are much more frequent than females now (Benton, New Nat 1998). Perhaps this will be the case a bit later.

Identifications
Species interactions

No interactions present.

Comments

Mydaea's picture

'Sticklers' would say that

'Sticklers' would say that you cannot tell from the image whether it is vestalis (if it is, it is severely faded on the yellow flashes) or bohemicus (which it most resembles). You can't therefore be 'as sure as you can be'. There has never been to my knowledge any reference to these two species as an 'aggregate'.

eucera's picture

vestalis/bohemicus

The likelihood is that this is B. vestalis - albeit a rather faded example. B. bohemicus hasn't been reliably recorded in central southern England for about 30 years.

The term "sticklers" does seem a tad prejorative to me. It is important to remember that data from sources such as iSpot may well be used in large scale data analyses in the future. It is absolutely imperative that accurate data enters the public domain. I know it can be frustrating that species can't be reliably determined to species level in the field or from pics... but sadly... that is the way it is.

It was mentioned in a different thread that work needs to be done to find field characters to make identification easier/possible. This has, of course been going on for 2 hundred years... and in many cases, nothing that is reliable has been found. Everyone would like id to be straightforward

Stuart
Chairman BWARS
www.bwars.com

orchid_b's picture

Sticklers

Thanks Stuart, great stat.

Regarding 'sticklers', the previous comment is an example. If we need to seriously entertain bohemicus as possible, I wonder how many years it would have to be unrecorded from the area before we become 'as sure as we can be' that this is vestalis. Fifty? A hundred? More?

It must be a good idea to share photos from an area where one or the other species is not found, which gives more people a chance to get experience of field characters of each, knowing that the photo is 99.lots of 9s percent likely to be one of them.

It would be useful if we had the option to agg. these two species on recording databases, though.

Jamie from Briantspuddle

Mydaea's picture

"It would be useful if we had

"It would be useful if we had the option to agg. these two species on recording databases, though."

Why? If you do this you would need to have an 'aggregate' for brown Thoracobombus; for lucorum/terrestris/soroeensis; for melanic sylvestris/hortorum/ruderatus; for lapidarius/ruderarius; and a mass of others when you move outside bumblebees.

If you have a cuckoo you can't identify for whatever reason there is a taxon already - Bombus (Psithyrus). Use that if you can't live with difficulty and uncertainty.

orchid_b's picture

Is there another species that

Is there another species that could be confused with these two and not distinguished except by gen. det? I would have thought it would be more useful to recorders to narrow the possibilities down a bit. We do this with moths quite a lot, but not with bumblebees it seems at the moment.

Just a suggestion though. Wouldn't want to upset anyone.

Jamie from Briantspuddle

eucera's picture

ID Comment

These are the ones most likely to be confused with one another.

It's not a question of upsetting anyone though Jamie, it's basically about what constitutes a full biological record. Several of your comments make it clear that accuracy is less important to you than submitting something. For datasets to have value they must be as free from error as possible. The BWARS data (for instance) has been used to advise a whole slew of scientific papers (including the "State of Nature" review of this year). Vague records are meaningless and are unusable in serious work.

I don't want to discourage recording, far from it, but I really want to encourage accurate recording above anything else. Quality outweighs quantity every time

Stuart
Chairman BWARS
www.bwars.com

Dluogs's picture

Thank you, Jamie, for your

Thank you, Jamie, for your wonderfully detailed notes and I also found the discussion that follows interesting. There is lots for a bee novice to learn from here!

orchid_b's picture

Stuart's comment

I hadn't noticed the Chairman of BWARS's comment until now following the kind one from Dluogs.

Is it not a bit silly to claim that anyone is "more interested in submitting something than accuracy'?

I think things have moved on a bit since the days of the only acceptable records being dead. Like the old birding days of 'what's hit is history, what's missed is mystery'.

With current birding, all records come with probabilities. They are assessed by recorders, local and national. There are few 100% certain records, and they are subject to review. A 'probable' Slender-billed Curlew record has recently been rejected twenty years later after some advances in Curlew i/d.

Entomology has been more used to dead insects as evidence rather than written descriptions or, with new technology, photographs. But it need not be so, and more forward-thinking field naturalists are waking up to this.

Compare the BWARS website, which is basically saying don't bother to use these photos for field identification with some German websites, or Stephen Falk's, which is hugely informative about field characters, and encourages beginners to look for them.

Going back to this record, my idea was to share photos of one of a tricky species pair, which with great probability could be identified on location. The actual record was submitted with my own probability assessment (on a scale of 5, 4), and the local recorder could then make their own assessment. I can't see what's wrong with this approach, and it certainly is not submitting something for the sake of it, without being worried about the record's accuracy.

In fact the usefulness of the submission is borne out by the recent comment just made, nearly a year later.

I hope others are not discouraged by Stuart's comments and the BWARS 'police' from making similar, and I think helpful, submissions of aculeate photos and annotations.

Jamie from Briantspuddle

eucera's picture

Jamie's comment

Jamie
I'm sorry that you suggest that my response is "unkind" in some way. Of course, it isn't at all - however, it is at variance with your stance

>>Is it not a bit silly to claim that anyone is "more interested in submitting something than accuracy'?

Not really silly - it just depends on how important accuracy is. There are quite few people who are happy with a broad taxon name on occasions(myself included) but I don't then submit it as a record because it isn't one.

>>I think things have moved on a bit since the days of the only acceptable records being dead. Like the old birding days of 'what's hit is history, what's missed is mystery'.

No one is saying this - it is a strawman argument. What I am saying is that the only real records are accurate ones. Of course things can be identified in the field and from photos - but just not everything or all the time

>>With current birding, all records come with probabilities. They are assessed by recorders, local and national. There are few 100% certain records, and they are subject to review. A 'probable' Slender-billed Curlew record has recently been rejected twenty years later after some advances in Curlew i/d.

This may well be true but is not really relevant to the discussion. There are fewer bird species, many hundreds of thousands of birders, many of the populations are smaller and the things are a lot larger than insects.

>>Entomology has been more used to dead insects as evidence rather than written descriptions or, with new technology, photographs. But it need not be so, and more forward-thinking field naturalists are waking up to this.

Entomologists use the full gamut of techniques - from specimens to photographs to descriptions to DNA (yes.... some sibling species can only be separated by looking at Barcodes). We all want things to be as comprehensive and user-friendly as possible - however, in a many cases the modern techniques (except DNA sampling) break down. Then what do you advocate we do? Detailed photographs of lots of living insects just a few mm long are simply not a viable option for a full identification. How do you see if the hairs on the third sternum are black or an admixture of black and white; how do you see the shape of the male genital capsule or the epicnemial carina? This is not necessary for lots of bees and wasps - but it is essential for others.

>>Compare the BWARS website, which is basically saying don't bother to use these photos for field identification with some German websites, or Stephen Falk's, which is hugely informative about field characters, and encourages beginners to look for them.

It says nothing of the sort - another strawman argument. We are very happy for folks to use photos to guide them, and also to make identifications. However, we also point out just how important it is not to rely solely on these field characters in many cases. How do you think BWARS member Steve Falk learnt his species id? I can tell you it wasn't entirely in the field

>>Going back to this record, my idea was to share photos of one of a tricky species pair, which with great probability could be identified on location. The actual record was submitted with my own probability assessment (on a scale of 5, 4), and the local recorder could then make their own assessment. I can't see what's wrong with this approach, and it certainly is not submitting something for the sake of it, without being worried about the record's accuracy.

As someone who does assess the validity of records (a lot), of course I am interested in how confident (and competent) the recorder is (you should see the number of "absolute cert" Asian Hornet records we have received - all (bar none) of which have been shown to be something else). Try looking at a pair, or a series, of pics of very similar things (eg small black Lasioglossums, male Andrena) and see where that gets us. If you scored your confidence in your id of something as 4/5 and in my experience it was extremely difficult to id in the field, and from an area from where the insect hadn't been seen for ages, it would not be accepted.

>>I hope others are not discouraged by Stuart's comments and the BWARS 'police' from making similar, and I think helpful, submissions of aculeate photos and annotations.

As I have said before - I am not trying to discourage people from having a go at all, and I spend literally hundreds of hours a year looking at photos (including here on WAB), answering emails and dealing with enquiries (all entirely voluntarily). There is no BWARS "police" either and to suggest as much is more than a bit unfair. However, BWARS as a Recording Society, needs to demonstrate that it has proper verification and validation protocols in place if our data is to be used with confidence - and this would clearly include not accepting data of things that we know are not identifiable in the field or from a particular photograph

Stuart
Chairman BWARS
www.bwars.com

orchid_b's picture

Stuart thanks for your long

Stuart thanks for your long and thoughtful response - in some contrast to your earlier rather offhand comment.

The bottom line is that an overwhelming probability of a photo being of one particular common species based on location is not enough for you to accept it. Which is a clear stance, but not shared by recorders of several other groups, and so I think worth discussing. But I think we have done enough just here.

I will however continue to post photos with what I see as potentially good field i/d characters and hope for constructive criticism about the features themselves, as well as hopefully encouraging others to do the same.

Meanwhile you might like to reflect on why solitary bee identification literature in Britain doesn't seem to have progressed recently, in contrast to most other insect groups. I hear things may change next year, however, and look forward to it.

Jamie from Briantspuddle