You pull a frame from your hive box on a warm afternoon, expecting to see the uniform, flat cappings of worker brood. Instead, you encounter a patch of cells that look bumpy, almost like bubble wrap or bullet casings popping out of the comb. New beekeepers frequently panic at this sight, worrying that their hive has a disease or a deformity.
Relax! You are likely just looking at male bees at the developmental stage. Knowing what a drone brood is and how to identify them stands as a critical skill for assessing the health and reproductive state of your colony.
Understanding the Role of the Drone Bee
To understand the brood, you must first understand the bee. A honeybee colony consists of three castes. The queen lays eggs. The workers, who are all female, do the foraging, cleaning, and guarding. Lastly, there are the drones, which are the male bees. They have one primary biological directive: mate with a virgin queen from another colony. Drones do not have stingers; they exist solely to pass on their genes.
Because drones are biologically larger than their female worker counterparts, they require more physical space to develop. A worker bee fits snugly into a standard honeycomb cell, but a drone needs a bit more room to accommodate its broader thorax and larger eyes. This size difference dictates how the nurse bees seal the cell once the larva is ready to pupate, giving the capping its unique appearance.
Identifying Drone Brood
Recognizing these cells is all about texture and elevation. Worker brood cappings are flat or slightly sunken, creating a smooth surface across the frame that resembles a biscuit. Drone brood cappings are convex, and they bulge outward from the comb surface.
Texture and Shape
When you look at a patch of drone brood, it resembles popcorn or the rounded end of a pistol bullet. This domed shape is the most reliable indicator. If you run your finger lightly over the frame (though you should avoid touching the brood if possible), you would feel the distinct bumps. The color of the wax cappings usually matches the surrounding worker brood, ranging from fresh yellow to older, darker brown, so rely on the shape rather than the color for identification.
Placement on the Frame
The location of these cells provides another clue. In a healthy hive with a fertile queen, the colony typically places drone brood on the periphery of the brood nest. You will usually find these bumpy cells along the bottom edge of the frame or in the corners. Bees naturally try to keep the central part of the frame for worker brood.
However, if you use foundationless frames, bees are free to build cells as needed. In these instances, you might see larger patches of drone comb integrated more centrally or in specific vertical sections. This is natural behavior and shows that the colony is preparing for the swarming season or simply wants a larger male population.
Distinguishing Normalcy From Problems
While drone brood is a natural part of a thriving colony, the pattern can sometimes indicate issues with your queen. A solid, compact pattern of worker brood with a ring of drone brood at the edges is ideal. It shows the queen is laying fertilized eggs (workers) in the center and unfertilized eggs (drones) at the edges.
The Spotty Pattern
If you see drone cells scattered randomly among worker cells, giving the frame a “shotgun” appearance, check your queen. As queens age, they may run out of stored sperm. At this stage, they begin laying unfertilized eggs in worker cells. The workers will still cap these cells, but because the drone larva is too large for the worker cell, the cap will bulge dramatically and look out of place, which may signal that you need to requeen the hive.
The Laying Worker
A more severe issue arises when a colony is without a queen for too long. Without the queen’s pheromones suppressing their ovaries, some worker bees will begin to lay eggs. Since workers cannot mate, they can only lay unfertilized eggs, which develop into drones.
If you see frames entirely filled with drone brood in worker cells, especially if there are multiple eggs per cell or eggs on the sides of the cell walls, then you likely have laying workers.
Managing Drone Brood and Varroa
Smart beekeepers use drone brood as a tool for pest control. The Varroa destructor mite, which is the primary enemy of the honeybee, prefers to reproduce inside drone cells. The longer development time of the drone pupa allows the mother mite to produce more offspring than she could in a worker cell.
You can leverage this biological preference. By inserting a specific green drone frame into the hive, you encourage the bees to build drone comb. Once the bees cap these cells, they contain a large percentage of the mites in the hive. You then remove the frame, freeze it to kill the mites and the drones, and return it to the hive. The bees clean out the dead matter and start over, offering a chemical-free way to lower mite counts.
Controlling the Population
Spring and early summer are peak times for drone production. The colony wants to spread its genetics during the swarm season. Therefore, seeing two or three frames with patches of drone brood during May or June is perfectly normal.
As autumn approaches, the dynamic changes. Drones are a drain on resources because they eat honey but contribute no labor. The worker bees will eventually evict the drones to conserve winter stores.
Seeing a lack of drone brood in late autumn is a sign that a colony is preparing properly for winter. However, finding heavy drone brood in October suggests a queen problem that will likely doom the colony if left unaddressed.
Keep Your Hive Healthy
Every inspection gives you a status report on your apiary. The textures and patterns on the frames tell a story about the queen’s fertility, the season, and the colony’s goals. Do not let the bumpy, bullet-shaped cappings scare you!
They are simply the male population developing exactly as nature intended. By understanding what a drone brood is and how to identify them, you move from being a bee-watcher to a true beekeeper, capable of interpreting the subtle language of the hive.
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