Fusion gives you the opportunity to remove weaker Bees from your Hive and receive a Gen 1 Egg in their place.  Hatching a Gen 1 Egg results in a Gen 1 male Bee.

Stats, traits, and moods cannot be controlled. They are randomly assigned when Eggs are Hatched, so you won't know the stats of the Bee you receive from Fusion until Hatching is complete. .

However, Gen 1 Eggs tend to produce stronger Bees than Gen 2 and Gen 3 Eggs.

NOTE: Gen Z Bees are not eligible for Fusion

Visit the Bee Lab to use Fusion

This chart shows you the Egg Hatching Mechanism and how the stats of the resuting Bee is determined: