Drones: The boys are back in town

Spring is upon us, with the snowdrops, crocus and daffodils out and cherry blossoms about to bloom. Inside the hives the population is still entirely female, the singular queen with her many thousands of female worker bees raising the brood (baby bees) and boosting the food stores after a long and wet winter. Within the next month or so, the queen will start laying male eggs and the adult drones emerge 24 days later.

One of the first drones of the year

Drones have an interesting life and that starts from their origin…drones have a grandfather but no father! This weird little quirk is a specialty of their evolution, when laying eggs the queen can decide whether to fertilise each individual egg. She measures the empty cell with her forelegs and if it’s a standard worker sized cell, she releases a sperm to fertilise the egg she’s about to lay (more on that later!) – but if the cell is a slightly larger drone cell, she lays her egg unfertilised. This means that the drone receives only genetic information from the queen and she can be sure that her lineage is continued through him with minimal dilution. This also means that he has half the number of chromosomes (a term called haploidy) compared to his sisters and mother. The drones develop the same way as the workers and the queen but take the longest to emerge from their cells, queens take 16 days from egg laying to adult emergence, workers take 21 days and drones take 24 days due to their larger size. The drones mature sexually around 10 days after emerging and are then ready to mate with a queen.

Drones will leave the hive and hang out in aerial groups called Drone Congregation Areas (DCAs) waiting for a queen. Think of a group of lads hanging out together outside a club hoping to meet a lady! DCAs are in roughly the same place every year which is interesting as no drones will make it through the winter to pass on the location (again, more on that later!) and while we humans are learning lots about how these sites are selected as a DCA (factors are mostly topographical and distance from colonies), we still have a lot that is unknown. Honeybees mate ‘on the wing’ which means they mate whilst flying, this ensures that the queen minimises the risk of mating with her siblings from the same hive and only mates with the fastest and fittest drones in the area. The queen has a special organ (called a spermatheca) in which she can store sperm collected from drones, this allows her to mate at the beginning of her life and not require further outings from the safety of the hive. She undertakes 1-3 mating flights within the first week or two of emerging from her cell, and she mates with an average of 12-14 individual drones. Once fully mated she can store and use the stored sperm at will and provided she is sufficiently mated, she can be the matriarch of the colony for up to 5 years. Once the drone has mated with a queen, that marks the end of his life as he dies in the act.

Spot the queen! Beekeepers sometimes mark queens with a dab of paint to make her easier to spot and identify which year she emerged

Due to this whole process taking place outside of the hive, it can only happen in the warmer and drier summer months. As colonies build in size, they start thinking about reproduction at the colony level; if something were to happen to the hive, the entire colony could be wiped out. I like to think of this as similar to the human body: the individual bees represent the cells in your body and if they stop being replaced then you will die just like the colony would dwindle and die. But in order to spread your genetics into the world you must reproduce (i.e. have a child) otherwise when you die your genetic line ends with you; similarly, the colony must reproduce to prevent their genetic line ending, we call this process ‘swarming’. As the drone’s main purpose of mating with a queen is limited to the summer months, the colony has no use for the drones over winter. Unfortunately drones are also built bigger than workers so they can sustain those long and fast mating flights, but this has the downside of making them require more fuel in the form of honey, an expensive resource in the hive over winter. So at the end of the summer, as the days are getting shorter and the weather closes in, it isn't uncommon to find fights breaking out at the hive entrance. Several workers can often be seen manhandling drones out of the hive, often biting his wings so he can’t return; although this seems incredibly brutal on the face of it, this is to maximise the chance of the colony making it through the winter months. Drones lack the glands required to feed the brood and don’t take part in hive maintenance or heating duties, they do however eat large quantities of the food stores which they didn’t contribute to building; essentially they become freeloaders. In the spring, this whole cycle begins again with new drones produced and sent out into the world!