What closed brood tells you three weeks early

A frame of capped brood is a promise. The bees inside it will emerge in roughly twelve days, work inside the hive for their first two or three weeks, and be out foraging about three weeks after that. Count the capped frames and you know, with less guesswork than any other reading, what the colony's workforce will look like a month from now.

This is why BeehiveMind records open and closed brood as two separate figures rather than one. Eggs and uncapped larvae tell you what the queen is doing right now. Capped brood tells you what the colony will be able to do later. Collapsing them into a single "brood" number throws away the timing, and the timing is the part you can act on.

The timeline behind the reading

A worker bee takes twenty-one days from egg to emergence: three days as an egg, about six as an open larva, and twelve sealed under a capping. Drones take twenty-four days and queens sixteen. Once you carry those three numbers in your head, every frame you lift is a calendar.

• Eggs mean the queen laid within the last three days. Standing on end in the bottom of the cell means today or yesterday; lying flat means the third day.
• Open larvae mean laying continued through the last nine days. Small, curled and swimming in jelly is young; filling the cell is about to be capped.
• Capped brood means the queen was laying between nine and twenty-one days ago, and those bees arrive over the next twelve.

So a frame with all three stages present, in roughly the proportions three eggs to six open to twelve capped, is a queen laying steadily. Anything else is information.

Reading the pair together

High open brood with low closed brood usually means the queen has only recently come into her stride: a new queen, one recovering from a dearth, or a colony that has just been fed into a spring build-up. The hive will look thin for another fortnight and then improve on its own. Nothing to do but note it.

The reverse, plenty of capped brood and almost no eggs, is the reading worth stopping for. It means laying has dropped off, and it dropped off at least nine days ago. Sometimes that is seasonal: a queen slows down in a dearth or in the autumn contraction. Sometimes she has swarmed or failed, and you have about two weeks of emerging bees to notice before the population starts to fall. The three queen readings settle which it is, and they take a minute.

What a healthy pattern looks like

A good frame of capped brood is boring. It is a flat, even slab of biscuit-coloured cappings, usually in an oval or a half-moon shape, with an arc of pollen above it and honey above that. The cappings are slightly domed on worker cells and much more so on drone cells, which cluster at the edges and bottom of the comb.

A poor pattern is the one beekeepers call pepper-pot: capped cells scattered among empty ones, in no particular shape. It means eggs were laid and something happened to a good share of them before capping. The candidates are a queen that is old, poorly mated or running out of sperm; a brood disease that the bees are removing; or brood that was chilled when the cluster contracted in a cold spell. Sunken, greasy or perforated cappings, or a smell you notice when you open the hive, push the answer towards disease, and the disease readings in the same inspection are how you record it.

Why the app asks for frames, not cells

Every quantity in BeehiveMind is relative to a whole frame, including the halves you round to. Counting cells is more precise and nobody does it twice. Counting frames is a judgement you can make with a frame in your hands and a phone in your pocket, and it stays consistent across a season, which is what makes the chart worth reading at the end of it.

It also makes the numbers comparable between hives. Three frames of capped brood in a colony with eight frames of bees is a different situation from three frames in a colony with three frames of bees, and both are visible on one row per visit, with the population reading next to the brood reading.

What to do with the number

• Capped rising, eggs present: the colony is building. Think about space: the seven out of ten rule says add a box when seven of ten frames are drawn and covered with bees, and capped brood is the reason the bees are about to arrive.
• Capped high, eggs gone, queen cells present: the colony has swarmed or is about to. Look for a virgin or wait for eggs; do not add a queen yet.
• Capped high, eggs gone, no cells: queen lost or failing. A frame of eggs from another hive buys time and tells you, by whether they draw cells on it, if they are queenless.
• Capped falling across three visits in the middle of the season: the reading the trend engine is built to catch. It is the earliest warning of a colony that will be weak by autumn, early enough to requeen or combine while there are still bees to do it with.

None of it needs a lab or a microscope. It needs the same two frame counts, written down every visit, by someone with their hands still in the hive. That is what the app is for.