When you look at a frame of brood, you are not seeing the present. You are seeing the colony's future — the population two weeks from now, the foragers three weeks hence, the strength of the hive in a month. The brood pattern tells you whether that future is bright or troubled.
Learning to read brood is the single most valuable skill a beekeeper can develop. Let us master it.
A healthy queen lays in a predictable pattern: starting at the center of a frame and working outward in concentric rings. She lays one egg per cell, moving methodically from cell to cell, filling each available space.
The result is a solid, compact brood pattern — an oval or circular area of capped brood with very few empty cells scattered throughout. It looks like a tightly packed mosaic, with 90% or more of the cells in the brood area filled.
What this tells you:
If you see this pattern, celebrate quietly. You are doing something right.
A spotty or "shotgun" brood pattern looks scattered and random — capped brood cells interspersed with empty cells, uncapped larvae, or cells that have been opened and cleaned out by the workers. Instead of a solid oval, you see a patchwork with 30-50% of cells empty or irregular.
This is a red flag. Something is wrong.
Possible causes:
An old or poorly mated queen may lay sporadically, skipping cells or laying infertile eggs that the workers remove. Her pheromone production may also be declining, causing the workers to raise replacement queen cells.
What to look for: Queen cups or swarm cells on the bottom of frames. If you see these alongside a spotty pattern, the workers are already planning to replace her.
Varroa mites reproduce inside capped brood cells. Heavy infestations kill pupae, and the workers remove the dead brood, leaving empty cells scattered throughout the pattern.
What to look for: Perform a mite check using either an alcohol wash or sugar shake — two simple methods for counting Varroa mites on a sample of bees. In an alcohol wash, you place about 300 bees in a jar with rubbing alcohol, shake to dislodge mites, and count them against the bee count to get a percentage. A sugar shake works similarly but uses powdered sugar instead of alcohol, so the bees survive. Both methods are covered in detail in Chapter 38. If mite levels exceed 3%, treat immediately.
Chalkbrood, sacbrood, or American Foulbrood can cause spotty patterns as workers remove diseased larvae.
What to look for: Sunken or perforated cappings, discolored larvae, foul smell. If you suspect AFB, do not open other hives until you've confirmed the diagnosis — AFB is highly contagious.
If the colony is starving or lacks pollen, the workers may cannibalize larvae to conserve resources.
What to look for: Empty honey frames, little to no stored pollen. Feed immediately if stores are low.
If you see more than one egg standing upright in a single cell — sometimes three, four, or even five eggs scattered on the cell walls instead of neatly placed at the bottom — you have laying workers.
This happens when a colony has been queenless for several weeks. Without the queen's pheromones to suppress ovary development, some workers begin laying eggs. But workers are unfertilized, so their eggs develop only into drones — and often, they can't even lay properly, scattering eggs haphazardly.
This is a serious problem. A laying worker colony cannot raise a new queen (they need fertilized eggs, and workers can't produce them). The colony is doomed unless you intervene.
Solutions:
Healthy brood cappings are slightly convex (domed) and uniform in color — a light tan or brown. If you see cappings that are sunken (caved inward) or perforated (with holes poked through), the brood inside is likely dead or diseased.
Sunken cappings: Often indicate American Foulbrood (AFB) or European Foulbrood (EFB). The larvae die inside the capped cell, and the workers sometimes try to clean them out, creating sunken or perforated cappings.
What to do:
Drone brood cappings are more convex than worker brood — they stick out like little bullets. If you see bullet-shaped cappings scattered throughout the worker brood area (instead of clustered at the edges or in dedicated drone comb), it suggests:
A small amount of drone brood in spring and early summer is normal — the colony is preparing to reproduce. But excessive drone brood, especially late in the season, is a warning sign.
You don't need to inspect every frame to assess brood health. Pull three frames from the center of the brood nest. If all three show a solid, compact pattern with eggs, larvae, and capped brood in proper stages, the colony is fine. Close up and move on.
If even one frame shows a spotty pattern, investigate further. Pull additional frames. Look for queen cells. Check mite levels. Rule out disease.
Don't ignore a spotty pattern. It will not resolve itself.
In late fall and winter, the queen slows or stops laying. You may see frames with capped honey where brood was in summer. This is normal — the colony is conserving resources and preparing for winter.
In early spring, you may see only a small patch of brood as the queen ramps up. This is also normal.
But in mid-summer, when the colony should be at peak strength, a small brood nest suggests problems. The queen may be failing, resources may be inadequate, or the colony may be diseased.
Healthy brood has no strong smell — or rather, it smells like the rest of the hive: warm wax, honey, propolis. It's pleasant.
Diseased brood smells foul. AFB smells like rotting meat. EFB smells sour. If you catch an unpleasant odor when you open the brood nest, investigate immediately.
The brood pattern is the clearest window into the colony's health. A solid pattern means the queen is strong, the workers are effective, and the colony has a bright future. A spotty pattern means trouble is brewing, and you need to act.
Learn to read this story. Your bees are writing it for you, frame by frame.
"A spotty brood pattern is the colony's way of waving a red flag. The only question is whether you'll notice before it's too late."
— The Observant Beekeeper