Swarming from the bees’ perspective

My notes from a second brilliant talk by Scottish bee farmer Tony Harris at our Cornwall Beekeepers Association/West Cornwall Beekeepers Association ‘Bit of a Do’ conference this September.

“What’s the earliest swarm you’ve had?” Tony asked the audience. The winner was: 23rd March! According to research by swarm expert Tom Seeley, most wild colonies swarm once in spring, but 40% of those swarms will swarm again before the end of the summer. Seeley’s studies indicate that the average survival rate of wild swarms may be low, with around 80% of swarms moving into natural cavities failing to survive their first winter.

Swarming countdown

Below is a photo I took of one of Tony’s slides, showing the timings leading up to a swarm, which I thought was quite helpful. Bee maths! He showed us some videos of behaviour such as the Dorsoventral abdominal vibration (DVAV) shaking dance, which can be done up to 300 times an hour on the old queen as the first queen cell is sealed. The workers grab hold of the queen and rapidly vibrate her. As a result, her egg laying behaviour is inhibited – she’s being harassed too much to have time to lay! The DVAV dances stop a few hours before the swarm departs. The workers will also do dances on sealed queen cells – communicating with the virgin queen inside.

Swarming countdown chart

Swarming countdown chart

Composition of a swarm

  • 70% of workers less than ten days old leave with the swarm.
  • Drones make up less than 1% of the swarm population

Choosing a new home

Once the swarm leaves, they will temporarily settle in a spot (such as an inconveniently high tree – or, for some lucky beekeepers, a low bush!). The swarm sends out a small number of scout bees, who will explore an area of up to 30 square miles in their search for an ideal home. Below is one of Tony’s slides summarising what a perfect bee home looks like, based on research by Winston and Seeley & Morse. Although bees are supposed to prefer high-up locations, Tony noted that he’s had more success with bait hives placed on the ground!

Swarm site selection criteria

Swarm site selection criteria

Meanwhile the swarm hangs clustered together. They can maintain their temperature at 35C in their core and 17C for the outside bees, regardless of the ambient temperature that day. The scout bees return to the cluster and carry out waggle dances for the best location they’ve discovered. If it happens to rain, the waggle dances will be paused!

Gradually, a consensus will be reached once all the scout bees are dancing for the same location.  When that happens, the cluster will soon take off and head for their new home. If you need to buy yourself some time while you get equipment ready to collect a swarm, Tony suggested gently spraying the hanging swarm with cold water (please don’t train a hose on them!). The reason behind this is that all the bees need to warm their flight muscles up to 35C to be ready to fly.

Virgin queens

Back in the old parent colony, the first virgin to emerge from her cell will often seek out any ‘quacking’ virgins still in their cells. The quacking noise is produced by the virgins vibrating their flight muscles, pressing their thorax against the comb as they do so. The emerged virgin’s sting is long enough to reach her rival queens and kill them before they hatch.

If two virgins emerge at the same time, they may fight, using their mandibles to grasp each other. Another possibility is that a virgin will leave with a secondary ‘cast’ swarm, taking a smaller number of bees off with her.

Aren’t swarms wonderful? As long as they’re not in your chimney, of course.

Emily Scott, CBKA member

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