Reading a brood pattern
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What good looks like
A solid oval of capped worker brood, edge to edge, with very few empty cells inside the pattern. Around it a band of pollen, and around that capped honey. Same shape on both faces.
The cappings are dry, slightly domed, and even in color. Larvae in open cells are pearly white, curled, and sitting in visible royal jelly.
| What you see | What it means | How serious |
|---|---|---|
| Solid oval of capped worker brood, dry even cappings, pearly curled larvae | A laying, well-mated queen | Normal |
| Capped cells scattered with gaps, the shotgun pattern | A failing queen, hygienic behavior, disease, or a young queen just starting | Look closer, not a diagnosis |
| Raised, bullet-shaped cappings on worker-sized cells | Drone brood where workers should be: a drone-laying queen or laying workers | Terminal unless corrected |
| Dark, sunken, pierced cappings over larvae collapsed to a brown mass | The signature of American foulbrood | Immediate, and reportable in most states |
Spotty brood
Capped cells scattered with gaps between them, the pattern people describe as shotgun. It has several possible causes and they are not equally serious:
- A failing or poorly mated queen, laying erratically.
- Hygienic behavior, where workers have removed diseased or mite-infested pupae. That is the colony doing its job, and it looks like a problem.
- Disease, which is the one to rule out.
- A young queen just starting, which fills in within two weeks.
Spotty brood means look closer. On its own it does not tell you what is wrong.
Domed cappings across the pattern
Drone brood in its own place, in larger cells at the edges of frames, is entirely normal.
Sunken, greasy, perforated cappings
This is the one to take seriously immediately. Cappings that are dark, sunken and pierced, over larvae that have collapsed into a brown mass, are the signature of American foulbrood, which is reportable in most states.
Do the rope test before doing anything else, and do not move frames between colonies while you are unsure.
What a pattern is not
It is not a judgment of the beekeeper, and a first-year colony often has an uneven pattern simply because it is building. Read it against the colony's age, the season, and what it looked like last time, which is why writing it down is worth the twenty seconds.