Marking a queen helps you to locate her so that you can safely transfer resources to other hives. You can also confirm that she has not been replaced. Place the queen in the tube and gently confine her against the plastic screen with the sponge plunger. Once she is confined against the plastic screen, gently mark her thorax with a queen marking pen. The color indicates the year a queen is introduced into a hive. This is a safe, efficient marking method.