Matching your Queen's Mood to the Mood of the Bees you send on a mission provides a stat boost. It improves your Bees' base stats depending on the mission type, such as Luck for Hunting, Agility, and Capacity for Harvesting, and all stats for PvP.

NOTE: Mood's are randomly assigned when a Bee is Bred or Hatched. You can't change the Mood of a male Bee. Queen's mood will change when she Breeds without Mood Stabilizer and with some upgrades.