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Which bumblebees pollinate bluebells?

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Hello everyone,
A query:-  I had the opportunity to visit a beautiful fragrant bluebell woodland yesterday and six different bumble species were spotted foraging white deadnettle and rhododendron [Bombus pascuorum q.; B.terrestris q. ; B. vestalis female; B. lucorum q.; B.lapidarius q; and B. hortorum q.] .  Throughout the afternoon, no bumbles were actually seen foraging the large masses of English blubells -  although they are said to be pollinators.  Has anyone noted which bumbles forage English bluebells?  Are the bells pollinated by long-tongued species such as B. pascuorum or B. hortorum?  These were not Spanish Bluebells.
I also located a bumble-sized circular nest hole on a wide grassy ride with a B. hortorum queen going in and out.
urbanbumble

     
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According to “Plants for Bees” by Kirk and Howes, the main visitors are all long-tongued queens - lapidarius, hortorum and pascuroum. However, short-tongued species such as terrestris can get nectar via the base - i.e. without pollinating. I would imagine that the bumblebees were finding the white dead-nettle and rhododendron and more rewarding and easier to work and hence not visiting the bluebells.

     
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Thanks for your helpful reply James.  It’s as I thought, with long-tongued queens doing the foraging.  I don’t very often go to bluebell woods to check it out for myself; and I haven’t actually got the Kirk & Howes book.
urbanbumble

     
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Our garden is in “blue mode” at present due to Forget-me-Not, Green Alkanet and Bluebells in full flower.
There are probably at least 2 - 3 square metres of bluebells all together, mainly densely gathered, but not all together.

I kept an eye on what insects visited the Bluebells this afternoon, while it was warm and sunny.
In summary - not much activity !

A smallish B. pratorum worker was working the bluebells pretty diligently for about 15 minutes, but didn’t come back.
A White Butterfly visited a small number of bluebell flowers - but also didn’t come back.
An Osmia rufa Solitary bee visited briefly.

A queen B. pascuorum (Common Carder) totally ignored the bluebells during several visits while visiting the flowers of Common Vetch some of which are amongst, or close to the bluebells.

To go back to the garden again, the Forget-me Nots are being worked by Osmia rufa and Honey Bees much of the time - and there was a small B. pratorum worker using them the other day. 
The Alkanet was being visited by Honey Bees, a B. hypnorum worker, a B. pratorum worker; a B. pascuorum queen and one or two Osmia rufa.

So, my view is that not many insects visit bluebell flowers - which fits with the level of insect activity one sees when out in the countryside on a Bluebell Walk !  - but they always set seed well.

Yours       Clive

     
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More information but this time on pollinators for wild bluebells.

We went for a bluebell walk on 5th May.  At least a kilometre of bluebells along the floor of a dry valley in the Chilterns and starting around noon.  Cloudy bright and dry. About 17C.  Bluebells coming towards peak of flowering.  There must have been millions of bluebell flowers available for the pollinating insects.

Again very few pollinators on the flowers, but I did spot two bumblebees working them.  Both queen size.
Just a glimpse of the first one - probably B. terrestris / lucorum.
The second was a B. hortorum, who was working the flowers very busily.

I also saw two nest searching queens, one B. lucorum, one B. lapidarius.

On the way back there were two bumblebees working dandelion flowers beside the track in grass.  A B. pratorum worker; and a B. lapidarius queen.

At home yesterday there was an Orange Tip butterfly and a B. pratorum worker on the bluebells in my garden.

Clive

     
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Great question- although I haven’t been observing bluebells for any great length of time I haven’t noticed a single bumblebee attracted to them here.

But I have noticed hoverflies, particularly Rhingia campestris.
Lovely little hoverfly with a red abdomen and a ‘nose’.

I wonder if they are important pollinators of bluebells or maybe bluebells aren’t as reliant on pollination and cope well through asexual reproduction.

elaine

     
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I was up in a wood in the Mendips where there’s a big open mossy, grassy area covered in bluebells and there were several of these Rhingia campestris visiting bluebells (see attached photo). There were also lots of solitary bees with huge pollen loads, some with nests in the mossy grass, and I presume they were getting their pollen from the bluebells (I was on a beewalk so I didn’t have time to check this out properly until later, by which time it was cloudy and drizzly and the bees were no longer active).

I did also see a single pascuorum queen feeding on bluebells, but not collecting pollen - I got some photos and its pollen baskets are empty.

 

     

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Thanks James.
urbanbumble

     
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Back in the Mendips woods again this afternoon and I found a pascuorum queen on a bluebell. It was a cool, windy, afternoon with just a bit of sunshine when I was in the bluebell patch and I wasn’t sure whether she was feeding or just clinging on at first. But when I got a bit closer, she went into a threat display as you can see. So she may have fed on the bluebell, but certainly wasn’t at this time.

     

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However, a few minutes later a rather fresh looking pratorum queen definitely was feeding on bluebells. I followed her for about two minutes and she fed on at least 10 different bluebell plants before I lost her. I would imagine that she must have pollinated several bluebells.

It would have been more conclusive evidence of bluebell pollination by B. pratorum if it had been a worker, of course, as a new queen will sample any flowers until she learns (a) which flowers are more rewarding, and (b) how to handle them efficiently. However, the fact that she visited several bluebells and was at each for a few seconds and had her head well placed to extract nectar does imply that there is sufficient reward to make it worth her while. The other main food source available to her would have been red campion, of which there were several nice patches about 100 metres away, but not much else.

     

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Thanks James

great photos and great observations.
haven’t seen any new pratorum queens here but males becoming more abundant since the 13th of May.

elaine

     
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Hello!
I was staying at Mersehead RSPB reserve self-catering cottage (Dumfries and Galloway) mid May and opposite the cottage was a small patch of bluebells opposite the cottage. Whenever the sun was on them, it attracted lots of butterflies - green-veined whites. I will try and attach a photo! Just feeding, or perhaps also pollinating? I also saw a common carder, but just the once.
The same week, at Rockcliffe, where there are banks of bluebells, there were common carders very much in evidence feeding at the bluebells. Also one garden bumblebee.
Whereas when we visited Kirkconnel flows, there is loads (and I mean loads!) of cranberries in flower and here we saw lots of short tongued species - earlies, red-tailed, buffs/white-tailed, an unknown cuckoo and maybe a worker tree bumblebee (just a glimpse, and these are still fairly new in Scotland).
Back home, north Glasgow, there was an early feeding away on the bluebells in my garden - which I thought ruined my theory of long-tongued species on bluebells, and short-tongued for the cranberries, but I see from above posts others have seen them on bluebells too.
Bluebell season now over, here!
Right, I will try and add the photos!

     

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Hello again!
I am posting again so that I can add the other photo.

     

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