Friday, 17 August 2012

Non-technical signs of life

Even when there's not a flying thing in sight, you can spot pollinator presence in a habitat through the tell-tale signs some leave behind (and no, I'm not talking about really tiny footprints in the butter).

I've posted previously about bumblebees apparently supping on cornflower (Centaurea) flowerbuds, before they were open - this is known as nectar robbing, and we saw it earlier in the season on a wide variety of plants, including Geraniums and Aquilegias.  A bee will bite through the fabric of a flower bud (petal, sepal, or whatever is in the way) to get a meal at the nectaries that lay hidden inside.  This will happen on flowers which are still closed, and also on those that have a trumpet longer than that bee's tongue.  In the fullness of time, those flowers will open, and then you will see the evidence of crimes past - here, the holes around the edge of a bindweed flower - that were made while the flower was still curled up, and the petals folded together. 

Bindweed flower, showing evidence of nectar-robbing
Leaf-cutter bees (Megachile sp.) take small, perfectly formed sections of leaf to make larval casings, using many plant species, such as bramble, honeysuckle, and trees such as this beech.

Leaf-cutter holes in beech leaves
These leaf sections are taken away to a sheltered spot and rolled up around some tasty food morsel, all ready for the larva to emerge from the egg that's laid alongside it.  A nice little parcel of pollinator potential!


  1. Very interesting. We have to look out for holes in bindweed flowers now. We have seen holes in comfrey flowers and watched short-tongued bumblebees robbing nectar through the holes in comfrey flowers which are normally only accessible for long-tongued bumblebees. A hole made by one bumblebee was normally used by lots of other short-tongued bumbles.
    We have also seen roses in some gardens with the distinct cut out leaf sections like on the pictures you posted.

  2. Yes, we've found similar - it seems, as with many things, that once you become aware of something, you suddenly see it everywhere!

  3. Peter and I spotted this in an allotment the other day - a very interesting example of nectar robbing!