Copper Bee Apiary

A garden apiary in Whittlesford, Cambridge, UK - honey bees and their beekeeper Hilary van der Hoff.

Exploded Drone

The other day, I found a dead drone lying on the roof of one of the hives. The striking thing was that he had died with his trousers down, so to speak. Drones die in the act of mating, leaving an essential part of their abdomen lodged in the queen. Until then, it is stowed inside as an "endophallus", being pushed out only when the drone engages with the queen in the final seconds of his life. The internal pressure that expels and ruptures the endophallus is fatal to the drone. In the case of this particular dead drone, it was evident that his undercarriage had been activated and the cargo released - it was all hanging out. Of course, I immediately did the proper thing: I took photographs of the poor undignified creature and posted them on the internet.

Here he is:

He is lying curled up, and from the end of his dark abdomen extends a browny white mass. You may also be able to see a bead of liquid hanging from his mouth, between his front legs - perhaps also forced out by that spike in internal pressure.

I gently lifted his body on to a microscope slide.

In the images from the microscope camera below, you can see what I saw...

Bead of liquid at the drone's mouth.

Bead of liquid at the drone's mouth.

Bits of endophallus...no longer endo.

Bits of endophallus...no longer endo.

At this magnification it's tricky to tell what's what. The dark furry thing is a back leg, and its hooked tip is a foot. The rest is the parts of a drone that we don't normally see.

Indeed I think this must be a very rare sight. Honey bees do not mate at home in (or on) their hive. Drones and queens in their hives simply ignore each other. Mating is done on the wing, remote from the hive. A virgin queen, recently emerged from her cell, will take a mating flight in her first weeks of life, and will mate with many drones from the surrounding area on that flight, hopefully getting a diverse genetic mixture of sperm. The millions of sperm will be stored in her body and measured out over subsequent years to fertilise the eggs that she lays for the rest of her life.

So had this drone delivered his package?

I'm not sure.

But I think maybe he didn't, because:

  1. The drone appears to have much of his mating apparatus still attached, whereas it should have been left behind in the queen if he had mated.
  2. None of my colonies at that time would have had virgin queens out on mating flights.
  3. Given that mating supposedly occurs in drone congregation areas remote from the hive, the chance of a mating taking place directly overhead so that the expended drone fell to earth to land precisely on the hive roof seems very small indeed.

But maybe he did, because:

  1. It is the mating season and there are other bee colonies in the area that could have had new queens out on mating flights.
  2. I don't have any better ideas to explain how he came to be lying there with his pants down.

I will leave you with another puzzle. Here are some more images from the microscope camera. What parts of the drone's body do they show? Click on a photograph to enlarge it, then you can scroll through them using arrows at the sides, and the answer will appear for each one if you position your mouse over the image.

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