Exercise 3 solution

1. Choose a healthy hive; the old queen is left behind.
2. Remove several brood combs containing eggs or larvae less than three days old.
3. Make sure the combs are covered with young nurse bees.
4. Place them in a small nucleus hive with other combs of honey and pollen.
5. The nurse bees, finding themselves queenless, begin building emergency queen cells from the eggs and larvae.

Age limit: less than three days old. Workers pick cells with eggs aged under three days to enlarge into queen cells and feed with royal jelly, so older brood may not be suitable. (The article states the limit; the "may not be suitable" is my inference from it.)