The magic of queen cups: here today, gone tomorrow

Inside: Worker bees build queen cups in anticipation of swarming or supersedure. The cups are like a foundation, providing a sturdy connection between brood combs and fully developed queen cells.

What is a queen cup?

One sparkling spring day you open your hive and find something weird. Scattered among your brood combs, you find waxen objects that resemble acorns or thimbles. They are nearly round, the size of a marble, with openings that face down. Fearing they may be swarm cells, you slash them away. Good riddance!

But a few days later, you notice the acorns have returned. Some may be empty, but others may contain eggs or larvae. What is it with these things?

Although many mysteries lurk within a bee hive, the appearance of queen cups is one of the most confounding. Some colonies produce many cups and others produce few. Some are built one day and torn down the next, while others remain undisturbed for years. 

Biologists say the frequency and extent of queen cup building may be genetically controlled, with some lines producing far more than others. But to most beekeepers, they seem entirely random.

The purpose of queen cups

At first, the purpose of queen cups seems clear. A queen cup is like the foundation of a house. It provides an anchor point for a large queen cell and gives the colony a  “head start” in case it needs to replace a queen in a hurry.

Queen cups begin as regular brood cells. The bees chose cells they want to use and then extend them, creating the characteristic acorn shape. If the queen cup becomes “charged” with an egg, the worker bees enlarge and extend the cell as the larva grows. Eventually, it resembles the classic peanut shape of a mature queen cell.

Supersedure

Because honey bees know they can lose their queen at any time, a little preparation makes good sense. When bees anticipate supersedure, they often build queen cups on the large flat faces of brood combs. Usually. But bees are unpredictable, so expect to find them most anywhere.

Swarming

Queen cups are also the precursors to swarm cells. The bees usually build these on the edge of a comb, along the bottom or side edges. Queen cups for swarming usually don’t last long: they are quickly extended into full-sized queen cells in preparation for the big event.

How eggs get into the cups

We can easily see queen cups appear and disappear. But what happens next is less apparent. Some beekeepers say they have seen their queen bee lay eggs in queen cups. Other beekeepers say they have never seen a queen go near a queen cup, no matter how long they watch.

Some beekeepers believe that workers move eggs into queen cups, but those who’ve watched and waited entire seasons, have never seen a worker move an egg into a queen cup. And those who’ve said they’ve seen it happen, have never been able to document it.

Over the last ten years or so, I’ve followed dozens of discussions regarding the movement of eggs. I admit to being swayed, first one way, then the other by compelling arguments, but I’m still not convinced that workers ever load queen cups.

Workers move eggs for different reasons

It is clear that sometimes workers move eggs. Workers have been observed moving eggs out of the brood nest and disposing of them. For example, evidence shows that workers will remove—or sometimes eat—the eggs of laying workers. The workers can identify imposter eggs because they lack the queen’s pheromones.

Because every colony, even in the presence of a healthy queen, has some number of laying workers, the disposal of non-queen eggs is fairly routine.

Some beekeepers believe that workers can also detect the presence of diploid drone eggs before they hatch. These eggs come from queens inseminated by close relatives. Removal of the eggs results in a “shot-brood” pattern—a brood nest with lots of empty cells.

The direction of egg movement

But moving eggs away from a particular place is different from moving eggs to a place. Do honey bees really do both?

Many beekeepers have seen cases where a queen cup built above a queen excluder suddenly contains an egg. They often conclude that the egg must have been moved there by a worker who carried it from the brood nest.

But does that make sense? If the queen cup is above the queen excluder, it is most likely outside of the brood nest. If it’s outside of the brood nest, it probably won’t be properly tended by nurse bees. Why would a worker move an egg to a place like that?

Unless you actually saw a worker drop it there, I would have my doubts. Maybe the egg was left by a laying worker. Remember, every colony has some. Perhaps a small queen wedged herself through the excluder and laid an egg in the cup? That seems improbable. But I’ve seen queens strolling in the most unlikely places, so it’s hard to rule out.

Remote queen cups rarely produce new bees

It would be very telling if we could follow one of these above-the-excluder eggs into adulthood. If it turned into a female, we would at least know the egg came from a mated queen. But if it was male, it could be from a mated queen or a laying worker. 

However, most queen cups are ultimately destroyed, whether they contain brood or not. If the egg begins to develop but the original queen is healthy and continues to lay, the workers usually destroy the cups and start new ones. In short, if the egg doesn’t develop it’s hard for us to say where it came from.

Emergency queen cells do not arise from queen cups

Although queen cups produce supersedure queens and swarm-induced queens, they don’t help with emergency queen cells. An emergency occurs when the queen dies or becomes unable to lay when no supersedure queens or swarm queens are being reared.

To raise an emergency queen, the workers choose some already existing eggs or young larvae to rear into queenhood. They do this by building an emergency cell around the chosen brood and feeding it with royal jelly.

Intercaste queens may emerge from emergency cells

So despite all the building and demolishing of queen cells, when the true emergency occurs, the bees must make the best of their situation and build a queen cell wherever they find eggs or very young larvae. But if the larvae are too old, they may develop into intercaste queens.

An intercaste queen is small but has the ability to mate and lay fertilized eggs. Once she begins laying eggs, she is usually superseded by one of her daughters. But in spite of her small size and short life, she can be a larger-than-life hero by saving the entire colony.

Tell us your queen cup stories

Queen cups are fascinating because they can solve many colony problems. But not all. And how eggs get into cups is still disputed. Most beekeepers agree that the current queen charges the cups, but others still insist it’s the workers. 

Just yesterday, I saw a new beekeeper’s training manual that left no room for discussion. It said, “Worker bees are responsible for loading each queen cup with a fertilized queen egg retrieved from the brood nest.” 

I would love to hear your thoughts and observations. What have you seen? Do you have a queen cup story to tell us?

Rusty
Honey Bee Suite