When studying honey bees, occasionally something happens that leads to new observations. Once I was mating queens in my observation hives. These colonies were in my bee house, a building holding 30 observation hives (see Figure 1). After the queens mated, I was planning to use these colonies in experiments on queen introduction later in the summer. The advantage of working with observation hives is that one can see the bees anytime, day or night, rain or shine. I knew these colonies all had adult unmated queens, which I had provided as queen cells.
About a week after emerging from their cells, the queens flew from their colonies to mate. With these observation hives, I watched queens return from their flights with mating signs from the drones. If I miss this rarely-seen bit of bee biology. I can still tell a queen has mated, when her abdomen has enlarged from egg production, even before I see any eggs in the comb. Unfortunately, some queens do not survive their mating flights.
Even though I watched a queen walking among the bees, ready to fly and mate just the day before, sometimes when I look again, say the next evening, I cannot find her. She is long overdue, and I know she will not return. What happened to her? No one can tell for certain, and the imagined calamities can only be listed. Maybe the queen was caught in a spider’s web. The queen could have been eaten by a predator, captured in flight by a dragonfly. Interestingly for dragonflies, I see them darting around my apiaries hunting for bees on the wing. If you are in the right place at the right time and look closely, sometimes you can see them carrying a bee. With a large insect net, good aim, and lightning-quick reflexes, they can be caught holding their prey. (I know people who collect dragonflies, and they are quite good at catching them.) It is not hard for me to imagine that agile predator swooping down on a slow-flying queen.
What else could have happened to the virgin queen? She could have become disoriented and flown off course to who knows where. In mating apiaries where many small colonies are kept close to each other, I have seen queens being attacked on the hive floor. It is quite likely these queens entered the wrong hive and were caught before reaching the brood nest. The bees would regard these queens as foreign and usually kill them.
When the queen fails to return from her mating flight, what happens to the queenless colony? If young brood remains, the bees could rear another queen. What if there is none, making the colony hopelessly queenless? This dire predicament is precisely what befell one of my observation hives. With a heavy spring workload, I just left this colony queenless for a few weeks.
Upon checking the colony again, it was still strong (for an observation hive). In the brood comb were eggs, but not queen-laid eggs, but rather worker-laid eggs. This situation is a common occurrence when bees are left queenless for some time. Normally the queen lays only one egg per cell, though occasionally she may put two eggs in a cell (see Figure 2a). In stark contrast, collectively the laying workers put multiple eggs per cell (see Figure 2b). Since workers are female, they can lay eggs even though virtually all of them develop into drones.
When the bees cap the lone surviving male larva, even in a worker cell, they construct the bullet-shaped cap, characteristic of a male pupa (see Figure 3). Drones reared in the smaller worker cells produce worker-sized drones (see Figure 4). Without a queen to replace the worker bees dying naturally, the colony will dwindle away and perish. If such a laying-worker colony is found in the apiary, the usual recommendation is just to unite it with a strong queen-right one. Matters are a little more complicated in the apiary when first encountering worker-sized drones.
If seeing worker-sized drones, which could be evicted dead in front of the hive, possibly as pupae, or as adults (alive or dead), they generally indicate some kind of queen problem. Likewise, bullet-shaped drone caps on worker cells indicate some kind of queen difficulty. With only the under-sized drone observation as adult or pupal brood, two possibilities exist: laying workers (no queen in the hive) or an infertile queen laying drone (male) eggs in worker cells.
The egg pattern in the cells resolves which condition is present. As noted above, multiple eggs in the cells indicates laying workers. Single eggs in the cells indicate a dysfunctional queen. With a dysfunctional queen, some of the brood caps could be correct, worker caps on worker cells, or mixed with drone caps on worker cells, or all could be the latter. If the colony remains strong with the drone-laying queen, requeening is the usual option depending on the availability of new queens. If not, remove the defective queen and unite the colony to another. For example, during the first spring inspections is a typical time to find severe cases of drone-laying queens. All of the brood is drone, right when the colony should have begun its early buildup. With the colony already small in the spring, suffering delayed buildup, and the general lack of queens for sale, the most expedient correction may be to remove the defective queen and unite the colony.
In the bee house, the occurrence of laying workers, while an unfortunate apiary problem, becomes an opportunity to see into the mostly hidden world of laying workers. Looking at all those brood cells crammed-full of eggs, a host of interesting questions springs to mind. Which workers laid the eggs? How many laying workers are in this small colony? How can you tell which ones lay eggs without dissecting them under a microscope to find the eggs in their thread-like ovaries? (I have done the dissections; it’s a tedious process.) And there are still more questions. What does it look like when a worker lays an egg in a cell, a position called oviposition?
One reason why beekeepers rarely see laying workers in the cells is because they are easily disturbed. Opening a frame hive in a typical apiary setting, the beekeeper smokes the …