I heard a lot of humming from a beech tree outside our house. It did not seem to be a swarm, or a bumblebee nest, and there is no blossom to feed on. Then I realised there were a lot of bumblebees on the undersides of leaves, particularly around the veins.
Before you click on the “read more” button, see if you can figure out what they are doing. Extra points if you identify the bumblebee species! Not visible in this photo, it has a white bum.
Answer: they were sucking the honeydew exuded by aphids. Perhaps because we are entering a late June Gap and blossom is harder to come by – also we’ve had 2 days of rain, which tends to wash nectar out of flowers.
Honeydew is a sugary liquid very low in other nutrients like proteins, but high in other stuff the bees cannot digest. Bees can make honey from it, but it tends to give them dysentry, so where it is common beekeepers remove it – in fact it’s a major crop in Germany’s Black Forest. There is a market; it is very dark brown in colour, with a rich fragrance of stewed fruit or fig jam, and is not as sweet as nectar honeys.
I believe the bumblebee is a Buff-Tailed, or White-Tailed Bumblebee worker, but I can’t tell which, so no bonus point for me.