How many Fireflies you get after completing a level depends on your character's remaining health. In "Protect the Chickens" mode it depends on how many Chickens you keep alive. After the Piggy Bank is unlocked, the Fireflies drop extra Gems into it.
How many Fireflies you get after completing a level depends on your character's remaining health. In "Protect the Chickens" mode it depends on how many Chickens you keep alive. After the Piggy Bank is unlocked, the Fireflies drop extra Gems into it.