Capping Cells
Verhalten der Bienen
Once the larva is fully grown, the workers seal the cell with an air-permeable wax cap.
Once the larva is fully grown, the workers seal the cell with an air-permeable wax cap. The grub then stretches out, spins a cocoon, and pupates. For the worker, the egg stage lasts three days and the larval stage six, so capping occurs around the ninth day and emergence on the 21st. The queen needs 16 days in total and is capped around the eighth day; the drone needs 24 days and is capped from the tenth day onward.
These figures are the key to the Varroa mite. The female mite enters the cell shortly before capping and reproduces exclusively there. Drone cells stay sealed for 14 days instead of 12, and in these two extra days one or two more mites can reach sexual maturity, which is why drone brood is preferentially infested. Up to 80 percent of a colony's mites sit in capped brood, where they are unreachable for treatment products. All biotechnical methods, from drone brood cutting through trap combs to total brood removal, are calculated around exactly these days.
This has nothing to do with the capping of honey cells. There the bees put on the cap once they have removed enough water from the honey; it is air-permeable but keeps out water vapor, since ripe honey attracts moisture. As a rule, the water content of capped cells is below 18 percent. Even so, the cap alone is not a sufficient harvest criterion, since bees sometimes cap honey that is still too moist. The refractometer settles the matter.