Check queen presence and egg laying
Searching for queen: Work with care and keep in mind that some of the queens can hide outstandingly well.
If you need to find the queen for marking, for instance, the unmarked queens can easily be found early in the season when there are quite few workers and only one or two boxes in the hive.
The queen usually goes to the empty built frames that have been recently given to the hive and to where the bees are. The queen might leave the hive while the hive is being searched.