Wednesday, 6 June 2012

Some Bombus behavioural obs

Bombus - aptly named bouncers!

It seems that our invertebrate friends are as jealous of their patch as anyone, and will do their utmost to turf out interlopers.  Bumblebees seem to be especially territorial, and bombastically biff hoverflies, bee-flies and other bee species off their clump of chives or out of their patch of forget-me-nots.  I have so far not managed to catch this bee-bouncing on film, but be assured I will post here as soon as I do!

The Bombus/knapweed question...

Bumblebees in a wildlife area of one of the city parks in Leeds were showing a lot of interest in knapweed flowers, despite the fact that the flower buds were still tightly closed.  Closer inspection suggested that they were supping something being exuded by the plant - you can see tiny droplets of something on the surface of the flower bud in the photo below....

The question is, was the knapweed excreting something from the flower buds, and, if so, to what end?  It didn't seem likely that the bees were engaged in nectar-robbing, as the scales on knapweed are fairly tough - but we're happy to be wrong about that, if anyone knows better!  Ideas on a postcard, please, or as a comment below ;)

As an aside (slightly) - the wildlife area in this park, planted with species such as geranium, day lilies, thyme, knapweed, was really buzzing with things; a stark contrast to nearby 'traditionally' planted areas (predominantly begonia, petunia and tagetes marigolds), which were noticeably lacking in invertebrate visitors.

Update (11 June):
The plant there is, I think, an ornamental cornflower, Centaurea montana, rather than a knapweed - I'm  only slowly getting to grips with these civilised plants!


  1. What time of day was it? Was there much dew/precipitation on the vegetation?

    Could it be that this is a rare observation of a bumblebee drinking water? (

  2. Hi there! Thanks for the link, I'll have to see if we can access that. Meanwhile, about the sighting: it was around 2pm, and fairly warm and sunny, so things were pretty dry. We actually saw this behaviour again today, in a garden in another part of Leeds - on the same plant (which is an ornamental cornflower, I believe, and not stricly a knapweed - must get round to changing that in my post). Some of the vegetation today was a touch damp, where it was heavily shaded and out of the breeze, but again, the flower buds in question were dry. And I haven't seen it on any of the wild knapweeds yet, but will be making note of any other interesting behaviour we come across, so please keep the ideas, thoughts and suggestions coming :)