It’s been another week of topsy-turvy temperatures, meaning that insects seem to have come and gone again. On Monday, a lunchtime walk with the dog coincided with the sun coming out, and the Maer seemed suddenly splashed with fiery yellow gorse. Buff-tailed Bumblebee workers were out in force on it, the orange-yellow pollen pasted to their pollen baskets like bright socks.
So many workers must mean that local nests are up and running. The queen will have already formed this, making a ball of soft, warm plant material in a hole of some sort. She will have foraged hard, building up fat reserves, and in her nest will have made a ball of pollen, covered in wax. Then she will have provisioned herself with a wax pot filled with nectar close by and laid eggs in the pollen ‘brood-clump’, on which she has then sat to incubate the eggs.
These first eggs will have been fertilised with sperm from a male with whom she mated at the end of last year, meaning that they emerge as females – workers, who then live in the nest and begin the ‘work’ of extending and caring for it, and the new broods laid by the queen. What I was seeing was these workers in full swing, gathering the pollen and nectar to take back to the nest. Though they might also be involved in using it to build inside, it’s likely that they may be specialising in foraging and will have passed it to other workers specialised in nest care. These roles are size dependent, the larger workers setting out to find resources whilst the smaller ones ‘stay home’. I love the idea of all this going on … while most passers-by may not even notice the bees at all!
As ever, these notes are taken from books I’ve been reading, notably Dave Goulson’s ‘Bumblebees: behaviour, ecology and conservation‘ that I referred to last week. It’s a brilliant book; more than just a popular guide and packed with references to research, yet very readable and informative. There is a lovely section on the way in which bees thermo-regulate their internal temperatures. They have hairy bodies of course, to insulate themselves, but the thorax – where the muscles used to power the flight are housed – has to be maintained at a certain temperature if they are to use them. They do this by shivering the muscles and, it seems, by ‘substrate cycling’; essentially burning glucose to make water and carbon dioxide and then recombining it again. In the process energy is released and warms the muscles; though there seems to be some discrepancy around the extent to which they use this over shivering. Perhaps an extra burst when the need arises for quick movement.
Whatever the outcome, energy is not unlimited, nor warming entirely efficient and it looked as though the ambient temperature dropped far enough during the rest of the week to prevent them getting airborne again, since all my other visits produced no bees at all. I have my fingers crossed that, with more icy weather, including snow, forecast for this coming week, the nests will survive. It also meant that the moth trap has stayed wrapped up too, with no sign of a change to make it worth unveiling yet.
If you saw last week’s post then you will also have seen that I set a small quiz, not about bees but about ‘beetles’, based on the other great book I’ve been looking at recently, of that title, by Richard Jones. I asked you to identify the impostor from four descriptions of beetles and their behaviour: a toxic poisoner, a flamethrower, a spiky, reversing killer and a Morse code user. I promised the answers this week, so here goes.
The poisoner is true – it refers to the Meloidae, oil beetles, which produce the toxin, though not in enough quantity to kill a human if ingested.
The flamethrower – amazingly – is also true. It’s the Bombardier beetle (Brachinus crepitans) which is resident, though declining, in the UK. It has a very rare relative (Brachinus sclopeta – streaked bombardier) which can do the same thing, and lots of foreign cousins too worldwide.
The Morse code user is also true – it’s the Deathwatch beetle (Xestobium rufovillosum) which is well known for its potentially destructive wood-eating.
That leaves the impostor as my fictitious Silphidae retrorsus. As far as I’m aware there is no beetle that can fly ‘retrorsus’ (backwards), nor which has specially sharpened elytra … though I wouldn’t be surprised if someone puts me right on this and I’d be delighted to hear about it, if so. I hope you enjoyed the puzzling as much as I enjoyed reading the book and making it up.
Stay warm this week, and think of the bees …